MIC2182 High-Efficiency Synchronous Buck Controller General

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MIC2182 High-Efficiency Synchronous Buck Controller General

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MIC2182
MIC2182
High-Efficiency Synchronous Buck Controller
General Description
Micrel's MIC2182 synchronous buck (step-down) switching regulator controller. N-channel synchronous architecture powerful output drivers allow output current capabilty. skip-mode control scheme allows efficiency exceed over wide range load current, making ideal battery powered applications, well high current distributed power supplies. MIC2182 operates from 4.5V input operate with maximum duty cycle lowdropout conditions. also features shutdown mode that reduces quiescent current 0.1µA. MIC2182 achieves high efficiency over wide output current range automatically switching between skip mode. Skip-mode operation enables converter maintain high efficiency light loads turning circuitry pertaining operation, reducing no-load supply current from 1.6mA 600µA. operating mode internally selected according output load conditions. Skip mode defeated pulling which reduces noise interference. MIC2182 available 16-pin (small-outline package) SSOP (shrink small-outline package) with operating range from -40°C +85°C.
Features
4.5V Input voltage range 1.25V Output voltage range efficiency 300kHz oscillator frequency Current sense blanking impedance MOSFET Drivers Drives N-channel MOSFETs 600µA typical quiescent current (skip-mode) Logic controlled micropower shutdown 0.1µA) Current-mode control Cycle-by-cycle current limiting Built-in undervoltage protection Adjustable undervoltage lockout Easily synchronizable Precision 1.245V reference output 0.6% total regulation 16-pin SSOP packages Frequency foldback overcurrent protection Sustained short-circuit protection input voltage output current capability power distribution systems Notebook subnotebook computers PDAs mobile communicators Wireless modems Battery-operated equipment
Applications
Typical Application
4.5V 30V* 100k MIC2182-3.3BSM SD103BWS 0.1µF
EN/UVLO
0.1µF
4.7µF
22uf Si4884 Si4884 10µH B140 VOUT 3.3V/4A 220uf
0.02
COMP SYNC
PGND VOUT VREF SGND
0.1µF 2.2nF
C13,
maximum input voltage limit standard MOSFET selection.
0.1µF
"Application Information" section 3.3V/10A other circuits.
4.5V-30V* 3.3V/4A Converter
Micrel, Inc. 1849 Fortune Drive Jose, 95131 (408) 944-0800 (408) 474-1000 http://www.micrel.com
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MIC2182
Ordering Information
Part Number MIC2182BM MIC2182-3.3BM MIC2182-5.0BM MIC2182BSM MIC2182-3.3BSM MIC2182-5.0BSM MIC2182YM MIC2182-3.3YM MIC2182-5.0YM MIC2182YSM MIC2182-3.3YSM MIC2182-5.0YSM Voltage Adjustable 3.3V 5.0V Adjustable 3.3V 5.0V Adjustable 3.3V 5.0V Adjustable 3.3V 5.0V Temperature Range -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C Package 16-pin narrow 16-pin narrow 16-pin narrow 16-pin narrow SSOP 16-pin narrow SSOP 16-pin narrow SSOP 16-pin narrow 16-pin narrow 16-pin narrow 16-pin narrow SSOP 16-pin narrow SSOP 16-pin narrow SSOP Lead Finish Standard Standard Standard Standard Standard Standard Pb-Free Pb-Free Pb-Free Pb-Free Pb-Free Pb-Free
Configuration
MIC2182
COMP SGND SYNC EN/UVLO PGND VOUT COMP SGND SYNC EN/UVLO VREF
MIC2182-x.x
PGND VOUT
Adjustable 16-pin 16-Pin SSOP (SM)
Fixed 16-pin 16-Pin SSOP (SM)
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MIC2182
Description
Number Name Function Soft-Start (External Component): Connect external capacitor ground reduce inrush current delaying slowing output voltage rise time. Rise time controlled internal current source that charges external capacitor VDD. PWM/Skip-Mode Select (Input): sets PWM-mode operation. capacitor ground sets automatic PWM/skip-mode selection. Compensation (Output): Internal error amplifier output. Connect capacitor series network compensate regulator control loop. Small Signal Ground (Return): Route separately from other ground traces terminal COUT. Frequency Synchronization (Input): Optional. Connect external clock signal synchronize oscillator. Leading edge signal above threshold terminates switching cycle. Connect SGND unused. Enable/Undervoltage Lockout (Input): Low-level signal powers down controller. Input below 2.5V threshold disables switching functions accurate undervoltage lockout (UVLO). Input below threshold forces complete micropower 0.1µA) shutdown. Reference Voltage (Output): 1.245V output. Requires 0.1µf capacitor ground. Feedback (Input): Regulates 1.245V. "Application Information" resistor divider calculations. Current-Sense High (Input): Current-limit comparator noninverting input. built-in offset 100mV between VOUT pins conjunction with current-sense resistor current-limit threshold level. This also positive input current sense amplifier. Current-Sense (Input): Output voltage feedback input inverting input current limit comparator current sense amplifier. [Battery] Unregulated Input (Input): +4.5V +32V supply input. Internal Linear-Regulator (Output): external MOSFET gate drive supply voltage internal supply Bypass SGND with 4.7µF. supply external loads. MOSFET Driver Power Ground (Return): Connects source synchronous MOSFET terminal Low-Side Drive (Output): High-current driver output external synchronous MOSFET. Voltage swing between ground VDD. Boost (Input): Provides drive voltage high-side MOSFET driver. drive voltage higher than input voltage minus diode drop. Switch (Return): High-side MOSFET driver return. High-Side Drive (Output): High-current driver output high-side MOSFET. This node voltage swing between ground Vdiode drop.
COMP SGND SYNC
EN/UVLO
(fixed) (adj)
VREF
VOUT
PGND
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Absolute Maximum Ratings (Note
Analog Supply Voltage (VIN) +34V Digital Supply Voltage (VDD) Driver Supply Voltage (BST) Sense Voltage (VOUT, CSH) -0.3V Sync Voltage (VSYNC) -0.3V Enable Voltage (VEN/UVLO) Power Dissipation (PD) 400mW 85°C SSOP 270mW 85°C Ambient Storage Temperature (TS) -65°C +150°C ESD, Note
Operating Ratings (Note
Analog Supply Voltage (VIN) +4.5V +32V Ambient Temperature (TA) -40°C +85°C Junction Temperature (TJ) -40°C +125°C Package Thermal Resistance (JA) 100°C/W SSOP (JA) 150°C/W
Electrical Characteristics
15V; open; VPWM VSHDN ILOAD 0.1A; 25°C, bold values indicate -40°C +85°C; Note unless noted Parameter MIC2182 [Adjustable], (Note Feedback Voltage Reference Feedback Voltage Reference Feedback Voltage Reference Feedback Bias Current Output Voltage Range Output Voltage Line Regulation Output Voltage Load Regulation Output Voltage Total Regulation MIC2182-3.3 Output Voltage Output Voltage Output Voltage Output Voltage Line Regulation Output Voltage Load Regulation Output Voltage Total Regulation MIC2182-5.0 Output Voltage Output Voltage Output Voltage Output Voltage Line Regulation Output Voltage Load Regulation Output Voltage Total Regulation Input Supply Mode Skip Mode Shutdown Quiescent Current Digital Supply Voltage (VDD) Undervoltage Lockout VPWM excluding external MOSFET gate drive current 0mA, VPWM floating (1nF capacitor ground) VEN/UVLO upper threshold (turn threshold) lower threshold (turn threshold)
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Condition
Units
1.233 1.220 4.5V 32V, VCSH VOUT 75mV 1.208
1.245 1.245 1.245
1.257 1.270 1.282
1.25 4.5V 32V, VCSH VOUT 50mV 25mV (VCSH VOUT) 75mV (PWM mode only) (VCSH VOUT) 75mV (full load range) 4.5V 3.267 3.234 4.5V 32V, VCSH VOUT 75mV 4.5V 32V, VCSH VOUT 50mV 25mV (VCSH VOUT) 75mV (PWM mode only) (VCSH VOUT) 75mV (full load range) 4.5V 4.95 4.90 6.5V 32V, VCSH VOUT 75mV 6.5V 32V, VCSH VOUT 50mV 25mV (VCSH VOUT) 75mV (PWM mode only) (VCSH VOUT) 75mV (full load range) 6.5V 4.85 3.201 0.03
0.03
3.333 3.366 3.399
0.03
5.05 5.10 5.150
1500
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Parameter Condition
Units
Reference Output (Fixed Versions Only) Reference Voltage Reference Line Regulation Reference Load Regulation Enable/UVLO Enable Input Threshold UVLO Threshold Enable Input Current Soft Start Soft-Start Current Current Limit Current-Limit Threshold Voltage Error Amplifier Error Sense Amplifier Gain Current Current Sense Amplifier Gain Oscillator Section Oscillator Frequency Maximum Duty Cycle Minimum On-Time SYNC Threshold Level SYNC Input Current SYNC Minimum Pulse Width SYNC Capture Range Frequency Foldback Threshold Foldback Frequency Gate Drivers Rise/Fall Time Output Driver Impedance Driver Nonoverlap Time Input Input Current
Note Note Note Note Note Note
1.220 IREF 100µA VEN/UVLO VCSH VOUT -3.5
1.245
1.270
-6.5
VOUT VOUT(nominal) 200mV VSYNC Note measured VOUT 0.75
0.95
1.15
3000pF source sink
VPWM
Exceeding absolute maximum rating damage device. device guaranteed function outside operating rating. Devices sensitive. Handling precautions recommended. Human body model, 1.5k series with 100pF. 25°C limits 100% production tested. Limits over operating temperature range guaranteed design production tested. VOUT (for feedback voltage reference output voltage line total regulation). applications information limitations maximum operating frequency.
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Typical Characteristics
Quiescent Current Temperature
CURRENT (mA) Skip
Quiescent Current Temperature
1.50
CURRENT (mA)
Quiescent Current Supply Voltage
CURRENT (mA)
1.00 0.50 UVLO Mode (mA)
INPUT VOLTAGE Skip
-0.50 0.20 0.15 0.10 0.05 SHUTDOWN (µA)
100120140 TEMPERATURE (°C)
100120140 TEMPERATURE (°C)
Quiescent Current Supply Voltage
REFERENCE VOLTAGE
VREF (Fixed Versions)
REFERENCE VOLTAGE
VREF (Fixed Versions)
1.260 1.250 1.240 1.230 1.220 1.210 1.200 1000 LOAD CURRENT (µA)
CURRENT (µA) -0.5 SUPPLY VOLTAGE UVLO Mode (mA)
1.256 1.254 1.252 1.250 1.248 1.246 1.244 1.242 1.240 1.238 1.236
Line Regulation
Load Regulation
SHUTDOWN (µA)
SUPPLY VOLTAGE
VREF (Fixed Versions)
REGULATOR VOLTAGE 1.260
REGULATOR VOLTAGE
Temperature
Line Regulation
5.00
Load Regulation
REFERENCE VOLTAGE
1.255
4.95
1.250
4.90
1.245
4.85
1.240 100120140 TEMPERATURE (°C)
SUPPLY VOLTAGE
4.80
LOAD CURRENT (mA)
REGULATOR VOLTAGE
4.98 4.96 4.94 4.92 4.90 4.88 4.86 4.84
Temperature
FREQUENCY VARIATION
Oscillator Frequency Temperature
FREQUENCY VARIATION 100120140 TEMPERATURE (°C) -0.2 -0.4 -0.6 -0.8 -1.0
Oscillator Frequency Supply Voltage
4.82 100120140 TEMPERATURE (°C)
SUPPLY VOLTAGE
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MIC2182
Soft-Start Current Temperature
OVERCURRENT THRESHOLD
Overcurrent Threshold Temperature
0.12
OUTPUT VOLTAGE
Current-Limit Foldback
VOUT 3.3V
CURRENT (µA) 100120140 TEMPERATURE (°C)
0.11
0.10
0.09
0.08 100120140 TEMPERATURE (°C)
OUTPUT CURRENT
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Block Diagrams
EN/UVLO
Reference
1.245V
4.7µF
VBST
Control Logic
CBST VOUT COUT
PGND Current Limit
Mode Skip Mode
0.024V
Skip-Mode Current Limit
0.07V
Comp
-2%VBG
OUTPUT
Hysteresis Comp Current Sense
CORRECTIVE RAMP
RESET
VOUT
SYNC
Oscillator
Error
COMP CCOMP RCOMP MIC2182 [adj.]
100k
SGND
VOUT 1.245V VOUT(max) 6.0V
Figure Adjustable Output Voltage Version
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MIC2182
EN/UVLO
Reference
1.245V
4.7µF
VBST
Control Logic
CBST VOUT COUT
PGND Current Limit
Mode Skip Mode
0.024V
Skip-Mode Current Limit
0.07V
Comp
-2%VBG
OUTPUT
Hysteresis Comp Current Sense
CORRECTIVE RAMP
RESET
VOUT
SYNC
Oscillator
82.5k 3.3V Output 150k Output SGND
Error
COMP CCOMP RCOMP MIC2182-x.x
100k
VREF
Figure Fixed Output Voltage Versions
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Control Loop Skip Modes Operation MIC2182 operates (pulse-width-modulation) mode heavier output load conditions. lighter load conditions, controller configured automatically switch pulse-skipping mode improve efficiency. potential disadvantage skip mode variable switching frequency that accompanies this mode operation. occurrence switching pulses depends component values well line load conditions. There external sync function that disabled skip mode. mode, synchronous buck converter forces continuous current flow inductor. skip mode, current through inductor settle zero, causing voltage ringing across inductor. Pulling (pin will force controller operate mode load conditions, which will improve cross regulation transformer-coupled, multiple output configurations. Control Loop MIC2182 uses current-mode control regulate output voltage. This method senses output voltage (outer loop) inductor current (inner loop). uses inductor current output voltage determine duty cycle buck converter. Sampling inductor current removes inductor from control loop, which simplifies compensation.
Functional Description
"Applications Information" following this section component selection information Figure Tables through predesigned circuits. MIC2182 BiCMOS, switched-mode, synchronous step-down (buck) converter controller. Current-mode control used achieve superior transient line load regulation. internal corrective ramp provides slope compensation stable operation above duty cycle. controller optimized high-efficiency, high-performance dc-dc converter applications. MIC2182 block diagrams shown Figure Figure MIC2182 controller divided into functions. Control loop operation Skip-mode operation Current limit Reference, enable, UVLO MOSFET gate drive Oscillator sync Soft start
Reference
1.245V
CONTROL LOGIC PULSE-WIDTH MODULATOR
4.7µF
VBST
CBST VOUT COUT
Mode Skip Mode
FORCES SKIP MODE 0.024V
PGND
COMPARATOR
Current Sense
VOUT
RESET
CORRECTIVE RAMP
Oscillator
COMP CCOMP RCOMP MIC2182 [adj.] Mode
Error
100k
VOUT 1.245V
Figure Operation
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block diagram MIC2182 current-mode control loop shown Figure mode voltage current waveforms shown figure inductor current sensed measuring voltage across resistor, RCS. ramp added amplified current-sense signal provide slope compensation, which required prevent unstable operation duty cycles greater than 50%. transconductance amplifier used error amplifier, which compares attenuated sample output voltage with reference voltage. output error amplifier COMP (compensation) pin, which compared current-sense waveform block. When current signal becomes greater than error signal, comparator turns high-side drive. COMP (pin provides access output error amplifier allows external components stabilize voltage loop.
Skip-Mode Control Loop
This control method used improve efficiency light output loads. light output currents, power drawn MIC2182 equal input voltage times supply current (IQ). light output currents, power dissipated significant portion total output power, which lowers efficiency power supply. MIC2182 draws less supply current skip mode disabling portions control drive circuitry when switching. disadvantage this method greater output voltage ripple variable switching frequency. block diagram MIC2182 skip mode shown Figure Skip mode voltage current waveforms shown figure
Reference
1.245V
CONTROL LOGIC SKIP-MODE LOGIC
4.7µF
VBST
CBST VOUT COUT
LOW-SIDE DRIVER SHOT
PGND
Skip-Mode Current Limit
0.07V
Comp
SHOT -2%VBG FORCES MODE
Hysteresis Comp
Current Sense
VOUT
MIC2182 [adj.] Skip Mode
VOUT 1.245V
Figure Skip-Mode Operation April 2004
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ILOAD Reset Pulse VHSD VLSD
Figure PWM-Mode Timing
VHSD VLSD VOUT ILIM(skip) Vone-shot VOUT
VNOMINAL
IOUT
Figure Skip-Mode Timing hysteretic comparator used place error amplifier current-limit comparator senses inductor current. one-shot starts switching cycle momentarily turning side MOSFET insure high-side drive boost capacitor, Cbst, fully charged. high-side MOSFET turned current ramps inductor, high-side drive turned when either peak voltage input current-sense comparator exceeds threshold, typically 35mV, output voltage rises above hysteretic threshold output voltage comparator. Once high-side MOSFET turned off, load current discharges output capacitor, causing VOUT fall. cycle repeats when VOUT falls below lower threshold, maximum peak inductor current depends skipmode current-limit threshold value currentsense resistor, RCS.
Iinductor(peak) 35mV sense
Figure shows improvement efficiency that skip mode makes when lower output currents.
EFFICIENCY
Skip 0.01
OUTPUT CURRENT
Figure Efficiency
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MIC2182 Switching from Skip Mode
current sense amplifier Figure monitors average voltage across current-sense resistor. controller will switch from skip mode when average voltage across current-sense resistor drops below approximately 12mV. This shown Figure average output current this transition level calculated below.
0.012 IOUT(skipmode)
rent-limit threshold 100mV+35mV -25mV. currentsense resistor must sized using minimum current-limit threshold. external components must designed withstand maximum current limit. current-sense resistor value calculated equation below:
75mV IOUT(max)
maximum output current
IOUT(max) 135mV
where: 0.012 threshold voltage internal comparator current-sense resistor value
Switching from Skip Mode
frequency occurrence skip-mode current pulses increase output current increases until hysteretic duty cycle reaches 100% (continuous pulses). Increasing current past this point will cause output voltage will drop. limit comparator senses output voltage when drops below output automatically switches converter mode. inductor current skip mode triangular wave shape minimum value maximum value 35mV/RCS (see Figure 7b). maximum average output current skip mode average value inductor waveform:
IOUT(max skipmode) 35mV
capacitor (pin discharged when transitions from skip mode. This forces remain mode fixed period time. added delay prevents unwanted switching between skip mode. capacitor charged with 10uA current source threshold 2.5V. delay typical capacitor
delay
CPWM Vthreshold 2.5V 250µs Isource 10µA
where: CPWM capacitor connected Current Limit current-limit circuit operates during mode. output current detected voltage drop across external current-sense resistor (RCS Figure 2.). cur-
current-sense pins (pin VOUT (pin noise sensitive signal level high input impedance. traces should short routed close each other. small (1nF 0.1µF) capacitor across pins will attenuate high frequency switching noise. When peak inductor current exceeds current-limit threshold, current-limit comparator, Figure turns high-side MOSFET remainder cycle. output voltage drops additional load current pulled from converter. When output voltage reaches approximately 0.95V, circuit enters frequency-foldback mode oscillator frequency will drop 60kHz while maintaining peak inductor current equal nominal 100mV across external current-sense resistor. This limits maximum output power delivered load under short circuit condition. Reference, Enable, UVLO Circuits output drivers enabled when following conditions satisfied: voltage (pin greater than undervoltage threshold (typically 4.2V). voltage enable greater than enable UVLO threshold (typically 2.5V) internal bias circuit generates 1.245V bandgap reference voltage voltage error amplifier voltage gate drive circuit. reference voltage fixed-output-voltage versions MIC2182 buffered brought VREF should bypassed (pin with 0.1µF capacitor. adjustable version MIC2182 uses output voltage sensing. decoupling capacitor used adjustable output voltage version.
Inductor Current
ILIM(skip)
35mV THRESHOLD ACROSS RCS.
Figure Maximum Skip-Mode-Load Inductor Current
IMIN(PWM) Inductor Current
12mV THRESHOLD AVERAGE VOLTAGE ACROSS RCS.
Figure Minimum PWM-Mode-Load Inductor Current Operation April 2004
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enable (pin threshold levels, allowing MIC2182 shut down current mode, turn output switching UVLO mode. enable voltage lower than shutdown threshold turns internal circuitry reduces input current typically 0.1µA. enable voltage between shutdown UVLO thresholds, internal bias, VDD, reference voltages turned soft-start forced internal discharge MOSFET. output drivers inhibited from switching remain state. Raising enable voltage above UVLO threshold 2.5V allows softstart capacitor charge enables output drivers. Either UVLO conditions will pull soft-start capacitor low. When drops below 4.1V When enable drops below 2.5V threshold MOSFET Gate Drive MIC2182 high-side drive circuit designed switch N-channel MOSFET. Referring block diagram Figure bootstrap circuit, consisting CBST, supplies energy high-side drive circuit. Capacitor CBST charged while low-side MOSFET voltage (pin approximately When high-side MOSFET driver turned energy from CBST used turn MOSFET MOSFET turns voltage increases approximately VIN. Diode reversed biased CBST floats high while continuing keep high-side MOSFET When low-side switch turned back CBST recharged through drive voltage derived from internal bias supply. nominal low-side gate drive voltage nominal high-side gate drive voltage approximately 4.5V voltage drop across fixed 80ns delay between high- low-side driver transitions used prevent current from simultaneously flowing unimpeded through both MOSFETs.
Oscillator Sync internal oscillator free running requires external components. nominal oscillator frequency 300kHz. output voltage below approximately 0.95V, oscillator operates frequency-foldback mode switching frequency reduced 60kHz. SYNC input (pin allows MIC2182 synchronize with external clock signal. rising edge sync signal generates reset signal oscillator, which turns low-side gate drive output. high-side drive then turns restarting switching cycle. sync signal inhibited when controller operates skip mode during frequency foldback. sync signal frequency must greater than maximum specified free running frequency MIC2182. synchronizing frequency lower, double pulsing gate drive outputs will occur. When used, sync must connected ground. Figure shows timing between external sync signal (trace low-side drive (trace high-side drive (trace R1). There delay approximately 250ns between rising edge external sync signal turnoff low-side MOSFET gate drive. Some concerns operating higher frequencies are: Higher power dissipation internal regulator. This occurs because MOSFET gates require charge turn device. average current required MOSFET gate increases with switching frequency. This increases power dissipated internal regulator. Figure shows total gate charge which driven MIC2182 over input voltage range, different values switching frequency. total gate charge includes both high- low-side MOSFETs. larger package capable dissipating more power than SSOP package drive larger MOSFETs with higher gate drive requirements.
LOW-SIDE HIGH-SIDE DRIVE DRIVE
SYNC SIGNAL
TIME
VOUT
TIME
Figure Sync Waveforms
Figure Startup Waveforms April 2004
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Reduced maximum duty cycle switching transition times constant delay times controller. switching frequency increased, switching period decreases. switching transition times constant delays MIC2182 start become noticeable. effect reduce maximum duty cycle controller. This will cause minimum input output differential voltage (dropout voltage) increase.
soft-start voltage applied directly comparator. internal current source used charge soft-start capacitor. capacitor discharged when either enable voltage drops below UVLO threshold (2.5V) voltage drops below UVLO level (4.1V). part switches minimum duty cycle when soft-start voltage less than 0.4V. This maintains charge bootstrap capacitor insures high-side gate drive voltage. soft-start voltage rises above 0.4V, duty cycle increases from minimum duty cycle operating duty cycle. oscillator runs foldback frequency 60kHz until output voltage rises above 0.95V. Above 0.95V, switching frequency increases 300kHz sync'd frequency), causing output voltage rise greater rate. rise time output dependent soft-start capacitor, output capacitance, output voltage, load current. oscilloscope photo Figure show output voltage soft-start voltage startup. Minimum Pulse Width MIC2182 specified minimum pulse width. This minimum pulse width places lower limit minimum duty cycle buck converter. When MIC2182 operating forced mode (pin low) when output current very zero, there limit ratio VOUT/VIN. this limit exceeded, output voltage will rise above regulated voltage level. minimum load required prevent output from rising This will occur output voltages greater than Figure should used guide when MIC2182 forced into PWM-only mode. actual maximum input voltage will depend exact external components used (MOSFETs, inductors, etc.).
GATE CHARGE (nC)
400kHz 500kHz 300kHz
SUPPLY VOLTAGE
Figure 10a. Gate Charge Input Voltage
SSOP
GATE CHARGE (nC)
300kHz 400kHz 500kHz SUPPLY VOLTAGE
Figure 10b. SSOP Gate Charge Input Voltage recommended that user limits maximum synchronized frequency 600kHz. higher synchronized frequency required, possible will design dependent. Please consult Micrel applications assistance. Soft Start Soft start reduces power supply input surge current startup controlling output voltage rise time. input surge appears while output capacitance charged slower output rise time will draw lower input surge current. Soft start also used power supply sequencing.
INPUT VOLTAGE
OUTPUT VOLTAGE
Figure Max. Input Voltage Forced-PWM Mode This restriction does occur when MIC2182 automatic mode (pin connected capacitor) since converter operates skip mode output current.
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output currents, core losses significant contributor. Core loss information usually available from magnetics vendor. Copper loss inductor calculated equation below: Pinductor Iinductor(rms)2 winding resistance copper wire, Rwinding, increases with temperature. value winding resistance used should operating temperature. winding(hot) winding(20°C) 0.0042 (Thot T20°C
Applications Information
following applications information includes component selection design guidelines. Figure Tables through predesigned circuits. Inductor Selection Values inductance, peak, currents required select output inductor. input output voltages inductance value determine peak peak inductor ripple current. Generally, higher inductance values used with higher input voltages. Larger peak peak ripple currents will increase power dissipation inductor MOSFETs. Larger output ripple currents will also require more output capacitance smooth larger ripple current. Smaller peak peak ripple currents require larger inductance value therefore larger more expensive inductor. good compromise between size, loss cost inductor ripple current equal maximum output current. inductance value calculated equation below.
VOUT (VIN(max) VOUT VIN(max) IOUT(max)
where: switching frequency ratio ripple current output current VIN(max) maximum input voltage peak-to-peak inductor current ripple current)
VOUT (VIN(max) VOUT VIN(max)
where: THOT temperature wire under operating load T20°C ambient temperature Rwinding(20°C) room temperature winding resistance (usually specified manufacturer) Current-Sense Resistor Selection inductance power resistors, such metal film resistors should used. Most resistor manufacturers make inductance resistors with temperature coefficients, designed specifically current-sense applications. Both resistance power dissipation must calculated before resistor selected. value RSENSE chosen based maximum output current maximum threshold level. power dissipated based maximum peak output current minimum overcurrent threshold limit.
RSENSE
75mV IOUT(max)
peak inductor current equal average output current plus half peak peak inductor ripple current.
IOUT(max)
maximum overcurrent threshold
Iovercurrent(max) 135mV
inductor current used calculate losses inductor. Iinductor(rms) IOUT(max) IOUT(max)
maximum power dissipated sense resistor
PD(R
SENSE
Iovercurrent(max)2
Maximizing efficiency requires proper selection core material minimizing winding resistance. high frequency operation MIC2182 requires ferrite materials most cost sensitive applications. Lower cost iron powder cores used increase core loss will reduce efficiency power supply. This especially noticeable output power. winding resistance decreases efficiency higher output current levels. winding resistance must minimized although this usually comes expense larger inductor. power dissipated inductor equal core copper losses. higher output loads, core losses usually insignificant ignored. lower
MOSFET Selection External N-channel logic-level power MOSFETs must used high- low-side switches. MOSFET gateto-source drive voltage MIC2182 regulated internal regulator. Logic-level MOSFETs, whose operation specified 4.5V must used. important note on-resistance MOSFET increases with increasing temperature. 75°C rise junction temperature will increase channel resistance MOSFET resistance specified 25°C. This change resistance must accounted when calculating MOSFET power dissipation. Total gate charge charge required turn MOSFET under specified operating conditions (VDS VGS). gate charge supplied MIC2182 gate drive circuit. 300kHz switching frequency above, gate April 2004
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charge significant source power dissipation MIC2182. output load this power dissipation noticeable reduction efficiency. average current required drive high-side MOSFET
IG[high-side](avg)
CISS COSS
where: IG[high-side](avg) average high-side MOSFET gate current total gate charge high-side MOSFET taken from manufacturer's data sheet with low-side MOSFET turned because freewheeling diode conducting during this time. switching losses low-side MOSFET usually negligable. Also, gate drive current lowside MOSFET more accurately calculated using CISS instead gate charge. low-side MOSFET:
IG[low-side](avg) CISS
where: CISS COSS measured gate drive current MIC2182) total high-side MOSFET switching loss
(VIN
where: switching transition time (typically 20ns 50ns) freewheeling diode drop, typically 0.5V. switching frequency, nominally 300kHz low-side MOSFET switching losses negligible ignored these calculations. Current MOSFET Power Dissipation Calculation Under normal operation, high-side MOSFET's current greatest when (maximum duty cycle). low-side MOSFET's current greatest when high (minimum duty cycle). However, maximum stress MOSFETs occurs during short circuit conditions, where output current equal Iovercurrent(max). (See Sense Resistor section). calculations below normal operation. calculate stress under short circuit conditions, substitute Iovercurrent(max) IOUT(max). formula below calculate under short circuit conditions. Dshort circuit 0.063 value high-side switch current
ISW(highside)(rms) IOUT(max)2
Since current from gate drive comes from input voltage, power dissipated MIC2182 gate drive Pgate drive IG[high-side](avg) IG[low-side](avg)
convenient figure merit switching MOSFETs onresistance times total gate charge (RDS(on) QG). Lower numbers translate into higher efficiency. gate-charge logic-level MOSFETs good choice with MIC2182. Power dissipation MIC2182 package limits maximum gate drive current. Refer Figure MIC2182 gate drive limits. Parameters that important MOSFET switch selection are: Voltage rating On-resistance Total gate charge voltage rating MOSFETs essentially equal input voltage. safety factor should added VDS(max) MOSFETs account voltage spikes circuit parasitics. power dissipated switching transistor conduction losses during on-time (Pconduction) switching losses that occur during period time when MOSFETs turn (PAC).
ISW(low side)(rms)
IOUT(max)2
IPP2
where: duty cycle converter
VOUT
Pconduction where:
Pconduction ISW(rms)2 PAC(off) PAC(on)
on-resistance MOSFET switch. Making assumption turn-on turnoff transition times equal, transition time approximated April 2004
efficiency converter. Converter efficiency depends component parameters, which have been selected. design purposes, efficiency used less than used greater than 10V. efficiency more accurately calculated once design complete. assumed efficiency grossly inaccurate, second iteration through design procedure made. high-side switch, maximum power dissipation Pswitch1(dc) RDS(on)1 ISW1(rms)2
M9999-042204
MIC2182
low-side switch (N-channel MOSFET), power dissipation Pswitch2(dc) RDS(on)2 2(rms)2 Since switching losses side MOSFET near zero, total power dissipation
Plow-side MOSFET(max) Pswitch2(dc)
circuit inductance will cause ringing during high-side MOSFET turn-on. external Schottky diode conducts lower forward voltage preventing body diode MOSFET from turning lower forward voltage drop dissipates less power than body diode. lack reverse recovery mechanism Schottky diode causes less ringing less power loss. Depending circuit components operating conditions, external Schottky diode will give 1/2% improvement efficiency. Figure illustrates difference noise with without Schottky diode. Output Capacitor Selection output capacitor values usually determined capacitors (equivalent series resistance). Voltage rating current capability other important factors selecting output capacitor. Recommended capacitors tantalum, low-ESR aluminum electrolytics, OS-CON. output capacitor's usually main cause output ripple. maximum value calculated
RESR VOUT
total power dissipation high-side MOSFET
PhighsideMOSFET(max) PSWITCH 1(dc)
External Schottky Diode external freewheeling diode used keep inductor current flow continuous while both MOSFETs turned off. This dead time prevents current from flowing unimpeded through both MOSFETs typically 80ns diode conducts twice during each switching cycle. Although average current through this diode small, diode must able handle peak current.
ID(avg) IOUT 80ns
reverse voltage requirement diode
Vdiode(rrm)
power dissipated Schottky diode
Pdiode ID(avg)
where: forward voltage peak diode current external Schottky diode, necessary circuit operation since low-side MOSFET contains parasitic body diode. external diode will improve efficiency decrease high frequency noise. MOSFET body diode used, must rated handle peak average current. body diode relatively slow reverse recovery time relatively high forward voltage drop. power lost diode proportional forward voltage drop diode. high-side MOSFET starts turn body diode becomes short circuit reverse recovery period, dissipating additional power. diode recovery
WITHOUT WITH FREEWHEELING DIODE FREEWHEELING DIODE
where: VOUT peak peak output voltage ripple peak peak inductor ripple current total output ripple combination output capacitance. total ripple calculated below: VOUT RESR
where: duty cycle COUT output capacitance value switching frequency voltage rating capacitor should twice output voltage tantalum greater aluminum electrolytic OS-CON. output capacitor current calculated below: (rms)
(rms)2 RESR(C
power dissipated output capacitor
PDISS(C
TIME
Figure Switch Output Noise With Without Shottky Diode
M9999-042204
Input Capacitor Selection input capacitor should selected ripple current rating voltage rating. Tantalum input capacitors fail when subjected high inrush currents, caused turning input supply Tantalum input capacitor voltage rating should least times maximum input voltage maximize reliability. Aluminum electrolytic, OS-CON, multilayer polymer film capacitors handle higher inrush currents without voltage derating. April 2004
MIC2182
input voltage ripple will primarily depend input capacitors ESR. peak input current equal peak inductor current,
Supply current MIC2182 MOSFET gate-charge power (included supply current) Core losses output inductor maximize efficiency light loads: gate-charge MOSFET smallest MOSFET, which still adequate maximum output current. Allow MIC2182 skip mode lower currents. ferrite material inductor core, which less core loss than iron power core. Under heavy output loads significant contributors power loss approximate order magnitude): Resistive on-time losses MOSFETs Switching transition losses MOSFETs Inductor resistive losses Current-sense resistor losses Input capacitor resistive losses (due capacitors ESR) minimize power loss under heavy loads: logic-level, on-resistance MOSFETs. Multiplying gate charge on-resistance gives Figure merit, providing good balance between high load efficiency. Slow transition times oscillations voltage current waveforms dissipate more power during turn-on turnoff MOSFETs. clean layout will minimize parasitic inductance capacitance gate drive high current paths. This will allow fastest transition times waveforms without oscillations. gate-charge MOSFETs will transition faster than those with higher gate-charge requirements. same size inductor, lower value will have fewer turns therefore, lower winding resistance. However, using small value will require more output capacitors filter output ripple, which will force smaller bandwidth, slower transient response possible instability under certain conditions. Lowering current-sense resistor value will decrease power dissipated resistor. However, will also increase overcurrent limit will require larger MOSFETs inductor components. low-ESR input capacitors minimize power dissipated capacitors ESR. Decoupling Capacitor Selection 4.7µF decoupling capacitor used minimize noise pin. placement this capacitor critical proper operation must placed right next
Iinductor(peak) RESR(C
input capacitor must rated input current ripple. value input capacitor current determined maximum output current. Assuming peak peak inductor ripple current low:
(rms) IOUT(max)
power dissipated input capacitor
PDISS(C (rms)2 RESR(C
Voltage Setting Components MIC2182-3.3 MIC2182-5.0 contain internal voltage dividers that output voltage. MIC2182 adjustable version requires resistors output voltage shown Figure
Error
VREF 1.245V MIC2182 [adj.]
Figure Voltage-Divider Configuration output voltage determined equation: VREF Where: VREF MIC2182 typically 1.245V. typical value between 10k. large allow noise introduced into voltage feedback loop. small value will decrease efficiency power supply, especially output loads. Once selected, calculated using:
VREF VREF
Voltage Divider Power Dissipation
reference voltage current through voltage divider.
Idivider power dissipated divider resistors
Pdivider (R1+ Idivider
Efficiency Calculation Considerations Efficiency ratio output power input power. difference dissipated heat buck converter. Under light output load, significant contributors are:
April 2004
M9999-042204
MIC2182
pins routed with wide trace. capacitor should good quality tantalum. additional ceramic capacitor necessary when driving large MOSFETs with high gate capacitance. Incorrect placement decoupling capacitor will cause jitter oscillations switching waveform large variations overcurrent limit. 0.1µF ceramic capacitor required decouple VIN. capacitor should placed near connected directly between (Vcc) (PGND). Layout Checklist layout critical achieve reliable, stable efficient performance. ground plane required control minimize inductance power, signal return paths. following guidelines should followed insure proper operation circuit. Signal power grounds should kept separate connected only location. Large currents high di/dt signals that occur when MOSFETs turn must kept away from small signal connections. connection between current-sense resistor MIC2182 current-sense inputs (pin should have separate traces, routed from terminals directly pins. traces should routed closely possible each other their length should minimized. Avoid running traces under inductor other switching components. 0.1µF capacitor placed between pins will help attenuate switching noise current sense traces. This capacitor should placed close pins
When high-side MOSFET switched critical flow current from input capacitor through MOSFET, inductor, sense resistor, output capacitor, back input capacitor. These paths must made with short, wide pieces trace. good practice locate ground terminals input output capacitors close each. When low-side MOSFET switched current flows through inductor, sense resistor, output capacitor, MOSFET. source low-side MOSFET should located close output capacitor. freewheeling diode, Figure conducts current during dead time, when both MOSFETs off. anode diode should located close output capacitor ground terminal cathode should located close input side inductor. 4.7µF capacitor, which connects terminal (pin must located right terminal very noise sensitive placement this capacitor very critical. Connections must made with wide trace. capacitor located bottom layer board connected with multiple vias. bypass capacitor should located close connected between pins Connections should made with ground power plane with short, wide trace.
M9999-042204
April 2004
MIC2182
Predesigned Circuits single schematic diagram, shown Figure used build power supplies ranging from common output voltages 1.8V, 2.5V, 3.3V, Components that vary, depending upon output current voltage, listed accompanying Tables through
Power supplies larger than also constructed using MIC2182 using larger power-handling components. "Power Supply Operating Characteristics" graphs following component vendor tables provide useful information about actual performance some these circuits.
100k 0.1µF
MIC2182 EN/UVLO COMP 0.1µF 2.2nF SYNC PGND
SD103BWS 0.1µF 4.7µF
(table)
(table) (table)
(table) (table)
(table) (table)
VOUT 0.1µF
C13, VOUT VREF SGND 0.1µF
Figure Basic Circuit Diagram with Tables through
Specification Switching frequency ripple Maximum ambient temperature Short-circuit capability Switching frequency
Limit output voltage 85°C Continuous 300kHz
Table Specifications Figure Tables through
Manufacturer Central Semiconductor Coiltronics Micrel Vishay/Lite (diodes) Vishay/Siliconix (MOSFETs) Vishay/Dale (inductors resistors) Sumida
Telephone Number (USA) (803) 946-0690 (516) 435-1110 (561) 241-7876 (704) 264-8861 (310) 322-3331 (408) 944-0800 (805) 446-4800 (800) 554-5665 (800) 487-9437 (847) 956-0666
Address www.avxcorp.com www.centralsemi.com www.coiltronics.com
www.irf.com www.micrel.com www.vishay-liteon.com www.siliconix.com www.vishaytechno.com www.japanlink.com/sumida
Table Component Suppliers
April 2004
M9999-042204
MIC2182
Reference (6.5V-30V) Part Description qty: TPSE227M010R0100 AVX, 220µF 10V, ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH125-100, Sumida Inductor, 10µH output inductor qty: Si4800, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2010 .025 Vishay, 0.025, 0.5W, current sense resistor MIC2182-5.0BSM MIC2182-5.0BM (6.5V-30V) Part Description qty: TPSE227M010R0100 AVX, 220µF 10V, ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH127-100, Sumida Inductor, 10µH output inductor qty: Si4800, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2010 .020 Vishay, 0.02, 0.5W, current sense resistor MIC2182-5.0BSM MIC2182-5.0BM (6.5V-30V) Part Description qty: TPSV227M010R0060 AVX, 220µF 10V, 0.06 ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH127-100 Sumida, 10µH output inductor qty: Si4884, Siliconix, low-side MOSFET qty: Si4884, Siliconix, high-side MOSFET qty: WSL-2512 .015 Vishay, 0.015, current sense resistor MIC2182-5.0BSM MIC2182-5.0BM
(6.5V-10V) Part Description qty: TPSV337M010R0060 AVX, 330µF 10V, 0.06 ESR, output filter capacitor qty: TPSV107M020R0085 AVX, 100µF 20V, 0.06 ESR, input filter capacitor qty: B330, Vishay, freewheeling diode qty: UP4B-3R3, Coiltronics, 3.3µH 11A, output inductor qty: Si4884, Siliconix low-side MOSFET qty: Si4884, Siliconix, high-side MOSFET qty: WSL-2512 .015 Vishay, 0.015, current sense resistor MIC2182-5.0BM
Table Components Output
Reference
(4.5V-30V) Part Description qty: TPSE227M010R0100 AVX, 220µF 10V, ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH125-100, Sumida Inductor, 10µH output inductor qty: Si4800, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2010 .025 Vishay, 0.025, 0.5W, current sense resistor MIC2182-3.3BSM MIC2182-3.3BM
(4.5V-30V) Part Description qty: TPSE227M010R0100 AVX, 220µF 10V, ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH127-100, Sumida Inductor, 10µH output inductor qty: Si4800, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2010 .020 Vishay, 0.02, 0.5W, current sense resistor MIC2182-3.3BM MIC2182-3.3BSM
(4.5V-30V) Part Description qty: TPSV227M010R0060 AVX, 220µF 10V, 0.06 ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH127-100 Sumida, 10µH output inductor qty: Si4800, Siliconix, low-side MOSFET qty: Si4884, Siliconix, high-side MOSFET qty: WSL-2512 .015 Vishay, 0.015, current sense resistor MIC2182-3.3BM MIC2182-3.3BSM
(4.5V-5.5V) Part Description qty: TPSV477M006R0055 AVX, 470µF 6.3V, 0.055 ESR, output filter capacitor qty: TPSV227M016R0075 AVX, 220µF 16V, 0.075 ESR, filter capacitor qty: B330, Vishay, freewheeling diode qty: UP4B-3R3, Coiltronics, 3.3µH 11A, output inductor qty: Si4884, Siliconix, low-side MOSFET qty: Si4884, Siliconix, high-side MOSFET qty: WSL-2512 .015 Vishay, 0.015, current sense resistor MIC2182-3.3BM
Table Components 3.3V Output
M9999-042204
April 2004
MIC2182
Reference (4.5V-30V) Part Description qty: TPSE227M010R0100 AVX, 220µF 10V, ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH125-100, Sumida Inductor, 10µH output inductor qty: Si4800, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2010 .025 Vishay, 0.025, 0.5W, current sense resistor MIC2182BSM MIC2182BM (4.5V-30V) Part Description qty: TPSE227M010R0100 AVX, 220µF 10V, ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH127-100, Sumida Inductor, 10µH output inductor qty: Si4884, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2010 .020 Vishay, 0.02, 0.5W, current sense resistor MIC2182BSM MIC2182BM (4.5V-30V) Part Description qty: TPSV227M010R0060 AVX, 220µF 10V, 0.06 ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH127-100 Sumida, 10µH output inductor qty: Si4884, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2512 .015 Vishay, 0.015, current sense resistor MIC2182BSM MIC2182BM
(4.5V-5.5V) Part Description qty: TPSV447M006R0055 AVX, 470µF 6.3V, 0.06 ESR, output filter capacitor qty: TPSV227M016R0075 AVX, 220µF 16V, 0.06 ESR, input filter capacitor qty: B330, Vishay, freewheeling diode qty: UP4B-3R3, Coiltronics, 3.3µH 11A, output inductor qty: Si4884, Siliconix low-side MOSFET qty: Si4884, Siliconix, high-side MOSFET qty: WSL-2512 .015 Vishay, 0.015, current sense resistor MIC2182BM
Table Components 2.5V Output
Reference
(4.5V-30V) Part Description qty: TPSE227M010R0100 AVX, 220µF 10V, ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH125-100, Sumida Inductor, 10µH output inductor qty: Si4800, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2010 .025 Vishay, 0.025, 0.5W, current sense resistor MIC2182BSM MIC2182BM
(4.5V-30V) Part Description qty: TPSE227M010R0100 AVX, 220µF 10V, ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH127-100, Sumida Inductor, 10µH output inductor qty: Si4884, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2010 .020 Vishay, 0.02, 0.5W, current sense resistor MIC2182BSM MIC2182BM
(4.5V-8V) Part Description qty: TPSV227M010R0060 AVX, 220µF 10V, 0.06 ESR, output filter capacitor qty: TPSE226M035R0300 AVX, 22µF 35V, ESR, input filter capacitor qty: B140, Vishay, freewheeling diode qty: CDRH127-100 Sumida, 10µH output inductor qty: Si4884, Siliconix, low-side MOSFET qty: Si4800, Siliconix, high-side MOSFET qty: WSL-2512 .015 Vishay, 0.015, current sense resistor MIC2182BSM MIC2182BM
(4.5V-5.5V) Part Description qty: TPSV447M006R0055 AVX, 470µF 6.3V, 0.06 ESR, output filter capacitor qty: TPSV227M016R0075 AVX, 220µF 16V, 0.06 ESR, input filter capacitor qty: B330, Vishay, freewheeling diode qty: UP4B-3R3, Coiltronics, 3.3µH 11A, output inductor qty: Si4884, Siliconix low-side MOSFET qty: Si4884, Siliconix, high-side MOSFET qty: WSL-2512 .015 Vishay, 0.015, current sense resistor MIC2182BM
Table Components 1.8V Output April 2004
M9999-042204
MIC2182
Power Supply Operating Characteristics
Effect Soft-Start Capacitor (CSS) Value Output Voltage Waveforms During Turn-On (10A Power Supply Configuration)
Effect Soft-Start Capacitor (CSS) Value Output Voltage Waveforms During Turn-On Power Supply Configuration)
Normal (300kHz Switching Frequency) Output Short-Circuit (60kHz) Conditions Switch Node (Pin Waveforms
Converter Waveforms
SWITCH-NODE VOLTAGE
VSW+HSD
HIGH-SIDE DRIVE VOLTAGE REFERENCED GROUND
3.3µH VOUT 3.3V IOUT
HIGH-SIDE MOSFET
HIGH-SIDE MOSFET GATE-TO-SOURCE VOLTAGE LOW-SIDE MOSFET GATE-TO-SOURCE VOLTAGE
QTY: Si4884 HIGH-SIDE MOSFETS QTY: Si4884 LOW-SIDE MOSFETS
(2A/div)
LOW-SIDE MOSFET
INDUCTOR CURRENT
10Amps
Typical Skip-Mode Waveforms
Typical PWM-Mode Waveforms
VOUT
(0.5A/div)
M9999-042204
(0.5A/div)
VOUT
April 2004
MIC2182
Load Transient Response Bode Plot Power Supply Configuration)
Load Transient Response Bode Plot (10A Power Supply Configuration)
VOUT
VOUT 3.3V 10µH
IOUT 5A/div
VOUT
VOUT 3.3V 3.3µH 7.5m
IOUT 2A/div
Bode Plot Power Supply Configuration)
GAIN (dB)
Efficiency Power Supply Configuration)
Skip EFFICIENCY
PHASE
Bode Plot (10A Power Supply Configuration)
GAIN PHASE
100x100 1x103 100x103 10x103 PHASE
GAIN (dB)
GAIN PHASE
100x100 1x103
10µH high-side MOSFET: Si4800 low-side MOSFET: Si4800 0.01 OUTPUT CURRENT
10x100
300x103
100x103
FREQUENCY (Hz)
300x103
10x100
10x103
FREQUENCY (Hz)
Efficiency Power Supply Configuration)
Skip 10µH high-side MOSFET: Si4800 low-side MOSFET: Si4800 0.01 OUTPUT CURRENT EFFICIENCY
Efficiency Power Supply Configuration)
Skip 10µH high-side MOSFET: Si4800 low-side MOSFET: Si4800 0.01 OUTPUT CURRENT
Efficiency (10A Power Supply Configuration)
Skip EFFICIENCY
EFFICIENCY
7.5m 3.3µH high-side MOSFETs: Si4884 low-side MOSFETs: Si4884
0.01
OUTPUT CURRENT
April 2004
M9999-042204
MIC2182
Package Information
0.157 (3.99) 0.150 (3.81)
DIMENSIONS: INCHES (MM)
0.020 (0.51) 0.050 (1.27)
0.020 (0.51) 0.013 (0.33) 0.0098 (0.249) 0.0040 (0.102)
0°-8° 0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79)
0.0648 (1.646) 0.0434 (1.102)
0.394 (10.00) 0.386 (9.80)
SEATING PLANE
16-pin
5.40 (0.213) 5.20 (0.205) 7.90 (0.311) 7.65 (0.301)
DIMENSIONS: (INCH)
0.875 (0.034) 6.33 (0.239) 6.07 (0.249) 2.00 (0.079) 1.73 (0.068)
0.22 (0.009) 0.13 (0.005)
0.38 (0.015) 0.25 (0.010)
0.21 (0.008) 0.05 (0.002) 0.65 (0.0260) COPLANARITY: 0.10 (0.004)
1.25 (0.049) 0.95 (0.037) 0.55 (0.022)
16-Pin SSOP (SM)
M9999-042204
April 2004
MIC2182
April 2004
M9999-042204
MIC2182
MICREL, INC. 1849 FORTUNE DRIVE JOSE, 95131
(408) 944-0800
(408) 474-1000
http://www.micrel.com
information furnished Micrel this data sheet believed accurate reliable. However, responsibility assumed Micrel use. Micrel reserves right change circuitry specifications time without notification customer. Micrel Products designed authorized components life support appliances, devices systems where malfunction product reasonably expected result personal injury. Life support devices systems devices systems that intended surgical implant into body support sustain life, whose failure perform reasonably expected result significant injury user. Purchaser's sale Micrel Products life support appliances, devices systems Purchaser's risk Purchaser agrees fully indemnify Micrel damages resulting from such sale. 2004 Micrel, Incorporated. M9999-042204
April 2004

MIC2182 High-Efficiency Synchronous Buck Controller General

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