4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
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19-0723; 11/07
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
MAX15004A/B/MAX15005A/B high-performance, current-mode controllers operate automotive input voltage range from 4.5V (load dump). input voltage down 2.5V after startup supplied external bias voltage. controllers integrate building blocks necessary implementing fixed-frequency isolated/nonisolated power supplies. general-purpose boost, flyback, forward, SEPIC converters designed with ease around MAX15004/MAX15005. current-mode control architecture offers excellent line-transient response cycle-by-cycle current limit while simplifying frequency compensation. Programmable slope compensation simplifies design further. fast 60ns current-limit response time, 300mV current-limit threshold makes controllers suitable high-efficiency, high-frequency DC-DC converters. devices include internal error amplifier accurate reference facilitate primary-side regulated, single-ended flyback converter nonisolated converters. external resistor capacitor network programs switching frequency from 15kHz 500kHz (1MHz MAX15005A/B). MAX15004A/B/MAX15005A/B provide SYNC input synchronization external clock. maximum FET-driver duty cycle MAX15004A/B 50%. maximum duty cycle MAX15005A/B selecting right combination input undervoltage lockout (ON/OFF) programs input-supply startup voltage used shutdown converter reduce total shutdown current down 10µA. Protection features include cycle-by-cycle hiccup current limit, output overvoltage protection, thermal shutdown. MAX15004A/B/MAX15005A/B available space-saving 16-pin TSSOP thermally enhanced 16-pin TSSOP-EP packages. devices operate over -40°C +125°C automotive temperature range.
Features
Wide 4.5V Operating Input Voltage Range Operates Down 2.5V (with Bootstrapped Bias) Current-Mode Control 300mV, Accurate Current-Limit Threshold Voltage Internal Error Amplifier with Accurate Reference Programmable Accurate Switching Frequency Switching Frequency Adjustable from 15kHz 500kHz (1MHz MAX15005A/B) External Frequency Synchronization (MAX15004) Adjustable (MAX15005) Maximum Duty Cycle Programmable Slope Compensation 10µA Shutdown Current Cycle-by-Cycle Hiccup Current-Limit Protection Overvoltage Thermal Shutdown Protection -40°C +125°C Automotive Temperature Range 16-Pin TSSOP 16-Pin Thermally Enhanced TSSOP-EP Packages
MAX15004/MAX15005
Ordering Information
PART PINPACKAGE DUTY CYCLE Programmable Programmable CODE U16E-3 U16-2 U16E-3 U16-2
MAX15004AAUE+ TSSOP-EP* MAX15004BAUE+ TSSOP MAX15005AAUE+ TSSOP-EP* MAX15005BAUE+ TSSOP
Applications
Automotive Vacuum Fluorescent Display (VFD) Power Supply Isolated Flyback, Forward, Nonisolated SEPIC, Boost Converters
Note: devices specified over -40°C +125°C temperature range.
+Denotes lead-free package. Exposed pad.
Configurations appear data sheet.
Maxim Integrated Products
pricing, delivery, ordering information, please contact Maxim Direct 1-888-629-4642, visit Maxim's website www.maxim-ic.com.
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
ABSOLUTE MAXIMUM RATINGS
SGND.-0.3V +45V PGND.-0.3V +45V ON/OFF SGND .-0.3V (VIN 0.3V) OVI, SLOPE, RTCT, SYNC, COMP, SGND .-0.3V (VREG5 0.3V) PGND.-0.3V +12V REG5 SGND .-0.3V PGND .-0.3V (VCC 0.3V) SGND PGND .-0.3V +0.3V Sink Current (clamped mode) .35mA Current 10µs transient) .±1.5A Continuous Power Dissipation* +70°C) 16-Pin TSSOP-EP (derate 21.3mW/°C above +70°C).1702mW 16-Pin TSSOP (derate 9.4mW/°C above +70°C) .754mW Operating Junction Temperature Range .-40°C +125°C Junction Temperature .+150°C Storage Temperature Range .-60°C +150°C Lead Temperature (soldering, 10s) .+300°C JEDEC51 Standard, Multilayer Board.
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN 14V, 0.1µF, CVCC 0.1µF 1µF, CREG5 1µF, VON/OFF 0.01µF, CSLOPE 100pF, 13.7k, 560pF, SYNC COMP unconnected, unconnected. -40°C +125°C, unless otherwise noted. Typical values +25°C. voltages referenced PGND, unless otherwise noted.) (Note (Figure
PARAMETER POWER SUPPLY Input Supply Range Operating Supply Current ON/OFF CONTROL Input-Voltage Threshold Input-Voltage Hysteresis Input Bias Current Shutdown Current INTERNAL 7.4V (VCC) Output (VCC) Voltage Point Line Regulation UVLO Threshold Voltage UVLO Hysteresis Dropout Voltage Output Current Limit Internal Clamp Voltage INTERNAL (REG5) Output (REG5) Voltage Point Line Regulation Dropout Voltage Output Current Limit IREG5-ILIM VREG5 7.5V, IREG5 15mA (sourcing) 5.5V 4.5V, IREG5 15mA (sourcing) IREG5 sourcing 4.75 4.95 0.25 5.05 mV/V IVCC-ILIM VUVLO-VCC VHYST-UVLO 4.5V, IVCC 20mA (sourcing) IVCC sourcing 10.0 VVCC-CLAMP IVCC 30mA (sinking) VVCC IVCC 20mA (sourcing) rising 3.15 7.15 0.25 10.4 10.8 3.75 7.60 mV/V VHYST-ON IB-ON/OFF ISHDN VON/OFF VON/OFF VON/OFF rising 1.05 1.23 1.40 40V, fOSC 150kHz 40.0 SYMBOL CONDITIONS UNITS
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
ELECTRICAL CHARACTERISTICS (continued)
(VIN 14V, 0.1µF, CVCC 0.1µF 1µF, CREG5 1µF, VON/OFF 0.01µF, CSLOPE 100pF, 13.7k, 560pF, SYNC COMP unconnected, unconnected. -40°C +125°C, unless otherwise noted. Typical values +25°C. voltages referenced PGND, unless otherwise noted.) (Note (Figure
PARAMETER OSCILLATOR (RTCT) Oscillator Frequency Range RTCT Peak Trip Level RTCT Valley Trip Level RTCT Discharge Current fOSC VTH,RTCT VTL,RTCT IDIS,RTCT VRTCT 13.7k, 4.7nF, fOSC (typ) 18kHz Oscillator Frequency Accuracy (Note 13.7k, 560pF, fOSC (typ) 150kHz 21k, 100pF, fOSC (typ) 500kHz 100pF, fOSC (typ) 1MHz MAX15004A/B Maximum Duty Cycle (Note Minimum On-Time SYNC Lock-In Frequency Range (Note SYNC High-Level Voltage SYNC Low-Level Voltage SYNC Input Current SYNC Minimum Input Pulse Width ERROR AMPLIFIER/SOFT-START Soft-Start Charging Current Reference Voltage Threshold HICCUP Enable Regulation Voltage VREF-FB rising COMP ICOMP -500µA +500µA COMP 0.25V 4.5V, ICOMP -500µA +500µA, 1.5V 1.5V ICOMP-SINK 1.5V, VCOMP 0.25V 1.215 1.215 1.228 1.228 1.240 1.240 VIH-SYNC VIL-SYNC ISYNC VSYNC -0.5 DMAX MAX15005A/B, 13.7k, 560pF, fOSC (typ) 150kHz 13.7k, 560pF, fOSC (typ) 150kHz +0.5 78.5 1.30 fOSC fOUT MAX15004A/B, fOSC fOUT MAX15005A/B 0.55 VREG5 VREG5 1.33 1.36 81.5 1000 SYMBOL CONDITIONS UNITS
MAX15004/MAX15005
tON-MIN
%fOSC
Input Offset Voltage Input Current COMP Sink Current
VOS-FB
-300
+300
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
ELECTRICAL CHARACTERISTICS (continued)
(VIN 14V, 0.1µF, CVCC 0.1µF 1µF, CREG5 1µF, VON/OFF 0.01µF, CSLOPE 100pF, 13.7k, 560pF, SYNC COMP unconnected, unconnected. -40°C +125°C, unless otherwise noted. Typical values +25°C. voltages referenced PGND, unless otherwise noted.) (Note (Figure
PARAMETER COMP Source Current COMP High Voltage COMP Voltage Open-Loop Gain Unity-Gain Bandwidth Phase Margin COMP Positive Slew Rate COMP Negative Slew Rate COMPARATOR Current-Sense Gain Propagation Delay Comparator Current-Sense Leading-Edge Blanking Time CURRENT-LIMIT COMPARATOR Current-Limit Threshold Voltage Current-Limit Input Bias Current ILIMIT Propagation Delay ILIM Comparator Current-Sense Leading-Edge Blanking Time Number Consecutive ILIMIT Events HICCUP HICCUP Timeout SLOPE COMPENSATION (Note Slope Capacitor Charging Current Slope Compensation Slope Compensation Tolerance (Note Slope Compensation Range ISLOPE VSLOPE 100mV CSLOPE 100pF CSLOPE 100pF CSLOPE 22pF CSLOPE 1000pF 10.5 11.2 mV/µs mV/µs VILIM IB-CS tPD-ILIM OUT= high, 0.3V From rising above VILIM (50mV overdrive) falling (excluding leading-edge blanking time) ACS-PWM tPD-PWM VCOMP (Note 0.15V, from VCOMP falling edge: 0.5V falling (excluding leading-edge blanking time) 2.85 3.15 SYMBOL ICOMPSOURCE VOH-COMP VOL-COMP AEAMP UGFEAMP PMEAMP SRCONDITIONS VCOMP 4.5V ICOMP (sourcing) 1.5V, ICOMP (sinking) VREG5 VREG5 -0.5 0.25 UNITS degrees V/µs V/µs
tCS-BLANK
tCS-BLANK
Clock periods
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
ELECTRICAL CHARACTERISTICS (continued)
(VIN 14V, 0.1µF, CVCC 0.1µF 1µF, CREG5 1µF, VON/OFF 0.01µF, CSLOPE 100pF, 13.7k, 560pF, SYNC COMP unconnected, unconnected. -40°C +125°C, unless otherwise noted. Typical values +25°C. voltages referenced PGND, unless otherwise noted.) (Note (Figure
PARAMETER OUTPUT DRIVER ROUT-N Driver Output Impedance ROUT-P Driver Peak Output Current OVERVOLTAGE COMPARATOR Overvoltage Comparator Input Threshold Overvoltage Comparator Hysteresis Overvoltage Comparator Delay Input Current THERMAL SHUTDOWN Shutdown Temperature Thermal Hysteresis TSHDN THYST Temperature rising
MAX15004/MAX15005
SYMBOL
CONDITIONS (applied externally), IOUT 100mA (sinking) (applied externally), IOUT 100mA (sourcing) COUT 10nF, sinking COUT 10nF, sourcing
UNITS
1000
IOUT-PEAK
VOV-TH VOV-HYST TDOVI IOVI
VOVI rising
1.20
1.228
1.26
From rising above 1.228V falling, with 50mV overdrive VOVI -0.5
+0.5
Note 100% production tested +125°C. Limits over temperature range guaranteed design. Note production tested, guaranteed design. Note MAX15005A/B, DMAX depends upon value Figure Oscillator Frequency/External Synchronization section. Note external SYNC pulse triggers discharge oscillator ramp. Figure During external SYNC, DMAX MAX15004A/B; MAX15005A/B, there shift DMAX with fSYNC/fOSC ratio (see Oscillator Frequency/ External Synchronization section). Note parameter measured trip point latch, with 0.3V, COMP. Note Slope compensation (2.5 10-9) CSLOPE mV/µs. Applications Information section.
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
Typical Operating Characteristics
(VIN 14V, 0.1µF, CVCC 0.1µF 1µF, CREG5 1µF, VON/OFF 0.01µF, CSLOPE 100pF, 13.7k, 560pF. +25°C, unless otherwise noted.)
UVLO HYSTERESIS TEMPERATURE
TEMPERATURE (°C)
MAX15004 toc01
SUPPLY CURRENT (ISUPPLY) OSCILLATOR FREQUENCY (fOSC)
SUPPLY CURRENT (mA) FREQUENCY (kHz) COUT COUT 10nF SHUTDOWN SUPPLY CURRENT (µA) MAX15005 220pF
MAX15004 toc02
SHUTDOWN SUPPLY CURRENT SUPPLY VOLTAGE
MAX15004 toc03
UVLO HYSTERESIS (mV)
+135°C
+25°C
-40°C SUPPLY VOLTAGE
OUTPUT VOLTAGE SUPPLY VOLTAGE
MAX15004 toc04
CLAMP VOLTAGE CURRENT SINK (IVCC)
10.50 10.25 10.00 9.75 9.50 9.25 9.00 8.75 8.50 8.25 8.00 7.75 7.50 7.25 7.00
MAX15004 toc05
REG5 OUTPUT VOLTAGE VOLTAGE
IREG5 (SOURCING)
MAX15004 toc06
IVCC IVCC
5.000 4.975 REG5 OUTPUT VOLTAGE 4.950 4.925 4.900 4.875 4.850 4.825 4.800 4.775 4.750 4.725 4.700
+25°C -40°C
OUTPUT VOLTAGE
CLAMP VOLTAGE
IVCC 20mA
+135°C +125°C
IREG5 15mA (SOURCING)
SUPPLY VOLTAGE
CURRENT SINK (mA)
10.0 10.5 VOLTAGE
REG5 DROPOUT VOLTAGE IREG5
0.28 0.25 0.23 0.20 0.18 0.15 0.13 0.10 0.08 0.05 0.03 VON/OFF
MAX15004 toc07
OSCILLATOR FREQUENCY (fOSC) SUPPLY VOLTAGE
MAX15004 toc08
OSCILLATOR FREQUENCY (fOSC) RT/CT
100pF OSCILLATOR FREQUENCY (kHz) 220pF 560pF 1000pF 1500pF 2200pF 3300pF
MAX15004 toc09
0.30 +125°C REG5 DROPOUT VOLTAGE
OSCILLATOR FREQUENCY (kHz) +125°C +135°C +25°C -40°C 13.7k 560pF MAX15005
1000
+135°C
+25°C -40°C IREG5 (mA)
10.5 15.5 20.5 25.5 30.5 35.5 40.5 45.5 SUPPLY VOLTAGE
1000
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
Typical Operating Characteristics (continued)
(VIN 14V, 0.1µF, CVCC 0.1µF 1µF, CREG5 1µF, VON/OFF 0.01µF, CSLOPE 100pF, 13.7k, 560pF. +25°C, unless otherwise noted.)
MAX15005 MAXIMUM DUTY CYCLE OUTPUT FREQUENCY (fOUT)
MAX15004 toc10
MAX15004/MAX15005
MAX15004 MAXIMUM DUTY CYCLE TEMPERATURE
MAX15004 toc11
MAX15005 MAXIMUM DUTY CYCLE TEMPERATURE
MAXIMUM DUTY CYCLE 560pF 13.7k fOSC fOUT 150kHz
MAX15004 toc12
MAXIMUM DUTY CYCLE OUTPUT FREQUENCY (kHz) 1000pF 560pF 220pF 3300pF 2200pF 1500pF 100pF
MAXIMUM DUTY CYCLE fOUT 75kHz
1000
TEMPERATURE (°C)
TEMPERATURE (°C)
MAXIMUM DUTY CYCLE fSYNC/fOSC RATIO
MAXIMUM DUTY CYCLE GAIN (dB) fSYNC/fOSC RATIO CRTCT 220pF RRTCT fOSC fOUT 418kHz
MAX15004 toc13
ERROR AMPLIFIER OPEN-LOOP GAIN PHASE FREQUENCY
100k FREQUENCY (Hz) GAIN
MAX15004 toc14
CS-TO-OUT DELAY TEMPERATURE
CS-TO-OUT DELAY (ns) PHASE (DEGREES) TEMPERATURE (°C) OVERDRIVE 190mV OVERDRIVE 50mV
MAX15004 toc15
MAX15005 560pF fOSC fOUT 180kHz
PHASE
DELAY THROUGH OVERVOLTAGE COMPARATOR
MAX15004 toc16
DRIVER OUTPUT PEAK SOURCE SINK CURRENT
MAX15004 toc17
POWER-UP SEQUENCE THROUGH
MAX15004 toc18
COUT 10nF VOUT VOVI VOUT 5V/div VON/OFF 10V/div 5V/div REG5 5V/div
VOUT 2V/div
VOVI 500mV/div
IOUT 1A/div
VOUT 5V/div
1µs/div
400ns/div
2ms/div
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
Typical Operating Characteristics (continued)
(VIN 14V, 0.1µF, CVCC 0.1µF 1µF, CREG5 1µF, VON/OFF 0.01µF, CSLOPE 100pF, 13.7k, 560pF. +25°C, unless otherwise noted.)
POWER-UP SEQUENCE THROUGH ON/OFF
MAX15004 toc20
POWER-DOWN SEQUENCE THROUGH
MAX15004 toc19
POWER-DOWN SEQUENCE THROUGH ON/OFF
MAX15004 toc21
VON/OFF 10V/div 5V/div REG5 5V/div VOUT 5V/div 4ms/div 1ms/div
ON/OFF 5V/div 5V/div REG5 5V/div
ON/OFF 5V/div 5V/div REG5 5V/div
VOUT 5V/div
VOUT 5V/div 400ms/div
LINE TRANSIENT STEP FROM 5.5V
MAX15004 toc22
LINE TRANSIENT STEP FROM
MAX15004 toc23
10V/div 5V/div REG5 5V/div
20V/div 5V/div REG5 5V/div
VOUT 5V/div
VOUT 5V/div
100µs/div
100µs/div
HICCUP MODE FLYBACK CIRCUIT (FIGURE
MAX15004 toc24
DRAIN WAVEFORM FLYBACK CONVERTER (FIGURE
MAX15004 toc25
ILOAD 10mA 200mV/div 10V/div VANODE 1V/div
ISHORT 500mA/div
10ms/div
4µs/div
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
Description
NAME ON/OFF FUNCTION Input Power Supply. Bypass with minimum 0.1µF ceramic capacitor PGND. ON/OFF Input. Connect ON/OFF always-on operation. externally program UVLO threshold supply, connect resistive divider between ON/OFF, SGND. Pull ON/OFF SGND disable controller. Overvoltage Comparator Input. Connect resistive divider between output power supply, OVI, SGND output overvoltage threshold. Programmable Slope Compensation Capacitor Input. Connect capacitor (CSLOPE) SGND amount slope compensation. Slope compensation (2.5 10-9) CSLOPE mV/µs with CSLOPE farads. Connection. internally connected. Oscillator-Timing Network Input. Connect resistor from RTCT REG5 capacitor from RTCT SGND oscillator frequency (see Oscillator Frequency/External Synchronization section.) Signal Ground. Connect SGND SGND plane. External-Clock Synchronization Input. Connect SYNC SGND when using external clock. Soft-Start Capacitor Input. Connect capacitor from SGND soft-start time interval. Internal Error-Amplifier Inverting Input. noninverting input internally connected Error-Amplifier Output. Connect frequency compensation network between COMP. Current-Sense Input. current-sense signal compared signal proportional error-amplifier output voltage. Low-Dropout Regulator Output. Bypass REG5 with ceramic capacitor SGND. Power Ground. Connect PGND power ground plane. Gate Driver Output. Connect gate external n-channel MOSFET. 7.4V Low-Dropout Regulator Output-Driver Power Source. Bypass with 0.1µF higher ceramic capacitors PGND. Exposed (MAX15004A/MAX15005A only). Connect SGND plane improve thermal performance. electrical connection.
MAX15004/MAX15005
SLOPE N.C. RTCT SGND SYNC COMP REG5 PGND
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
Functional Diagram
MAX15004A/B MAX15005A/B
1.228V PREREGULATOR ON/OFF COMP 7.4V 10.5V 30mA CLAMP REFERENCE 3.5V UVLO DRIVER
ON/OFF
PGND THERMAL SHUTDOWN
REG5
1.228V
OV-COMP
RESET
ILIMIT COMP
0.3V 50ns LEAD DELAY
PWMCOMP OVRLD SLOPE SLOPE COMPENSATION
RTCT
OSCILLATOR
SS_OK EAMP 1.228V
COMP
SGND RESET SYNC CONSECUTIVE EVENTS COUNTER
REF-AMP OVRLD
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
Detailed Description
MAX15004A/B/MAX15005A/B high-performance, current-mode controllers wide inputvoltage range isolated/nonisolated power supplies. These controllers general-purpose boost, flyback, SEPIC controllers. input voltage range 4.5V makes ideal automotive applications such vacuum fluorescent display (VFD) power supplies. internal low-dropout regulator (VCC regulator) enables MAX15004A/B/MAX15005A/B operate directly from automotive battery input. input operating range 2.5V when external source (e.g. bootstrap winding output) applied input. 2.5V input voltage range allows device operation from cold crank automotive load dump. undervoltage lockout (ON/OFF) allows devices program input-supply startup voltage ensures predictable operation during brownout conditions. devices contain internal regulators, REG5. regulator output voltage 7.4V REG5 regulator output voltage ±2%. output includes 10.4V clamp that capable sinking 30mA current. input undervoltage lockout (UVLO) circuit monitors voltage turns converter when voltage drops below 3.5V (typ). Internal Regulators REG5 section method obtain lower than 4.5V input operation with MAX15004/MAX15005. external resistor capacitor network programs switching frequency from 15kHz 500kHz. MAX15004A/B/MAX15005A/B provide SYNC input synchronization external clock. (FET-driver output) duty cycle MAX15004A/B 50%. maximum duty cycle MAX15005A/B selecting right combination RTCT discharge current trimmed allowing accurate setting duty cycle MAX15005. internal slope-compensation circuit stabilizes current loop when operating higher duty cycles programmed externally. MAX15004/MAX15005 include internal error amplifier with accurate reference regulate output nonisolated topologies using resistive divider. internal reference connected noninverting input error amplifier increased controlled manner obtain soft-start. capacitor connected ground programs soft-start reduce inrush current prevent output overshoot. MAX15004/MAX15005 include protection features like hiccup current limit, output overvoltage, thermal shutdown. hiccup current-limit circuit reduces power delivered electronics powered MAX15004/MAX15005 converter during severe fault conditions. overvoltage circuit senses output using path different from feedback path provide meaningful overvoltage protection. During continuous high input operation, power dissipation into MAX15004/MAX15005 could exceed limit. Internal thermal shutdown protection safely turns converter when junction heats 160°C.
MAX15004/MAX15005
Current-Mode Control Loop
advantages current-mode control overvoltagemode control twofold. First, there feed-forward characteristic brought controller's ability adjust variations input voltage cycleby-cycle basis. Secondly, stability requirements current-mode controller reduced that single-pole system unlike double pole voltage-mode control. MAX15004/MAX15005 offer peak current-mode control operation make power supply easy design with. inherent feed-forward characteristic useful especially automotive application where input voltage changes fast during cold-crank load dump conditions. While current-mode architecture offers many advantages, there some shortcomings. higher duty-cycle continuous conduction mode operation where transformer does discharge during duty cycle, subharmonic oscillations appear. MAX15004/MAX15005 offer programmable slope compensation using single capacitor. Another issue noise turn-on primary switch that cause premature cycle. current-limit comparator inputs have leadingedge blanking. shortcomings current-mode control addressed MAX15004/ MAX15005, making ideal design automotive power conversion applications.
Internal Regulators REG5 internal converts automotive battery voltage input 7.4V output voltage (VCC). output 7.4V operates dropout mode input voltages below 7.5V. internal capable delivering 20mA current, enough provide power internal control circuitry gate drive. regulated keeps driver output voltage well below absolute maximum gate voltage rating MOSFET especially during double battery load dump conditions. auxiliary winding output output once power supply turned bootstrap winding necessary proper
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
operation power supply; however, reduce power dissipation internal LDO, disabled applying external voltage higher than 7.4V (LDO output). then stops drawing current from thereby reducing power dissipation voltage clamped 10.4V with 30mA current sink case there higher voltage bias winding. This feature useful applications with continuous higher input voltage. second regulator from REG5 provides power internal control circuits. This also used source 15mA external load current. Bypass REG5 with parallel combination 0.1µF low-ESR ceramic capacitors. Additional capacitors 22µF) used although they necessary proper operation MAX15004/MAX15005.
MAX15004A/B MAX15005A/B
ON/OFF 1.23V
Figure Setting MAX15004A/B/MAX15005A/B Undervoltage Lockout Threshold
Startup Operation/UVLO/ON/OFF
MAX15004A/B/MAX15005A/B feature undervoltage lockouts (UVLO). internal UVLO monitors VCC-regulator turns converter once rises above 3.5V. internal UVLO circuit about 0.5V hysteresis avoid chattering during turn-on. Once power bootstrapped voltage feeds VCC, voltage drop below This feature provides operation cold-crank voltage 2.5V. external undervoltage lockout achieved controlling voltage ON/OFF input. ON/OFF input threshold 1.23V (rising) with 75mV hysteresis. Before operation commence, ON/OFF voltage must exceed 1.23V threshold. Calculate Figure using following formula: VUVLO where VUVLO ON/OFF's 1.23V rising threshold, desired input startup voltage. Choose value 100k range. UVLO circuits keep comparator, ILIM comparator, oscillator, output driver shut down reduce current consumption (see Functional Diagram). ON/OFF input used disable MAX15004/MAX15005 reduce standby current less than 20µA.
also controls soft-start period. startup, after applied UVLO thresholds reached, device enters soft-start. During soft-start, 15µA sourced into capacitor (CSS) connected from causing reference voltage ramp slowly. HICCUP mode operation disabled during softstart. When reaches 1.228V, output well HICCUP mode become fully active. soft-start time (tSS) using following equation: 1.23(V) 10-6
where seconds farads. soft-start programmability important control input inrush current issue also avoid MAX15004/MAX15005 power supply from going into unintentional hiccup during startup. required soft-start time depends topology used, currentlimit setting, output capacitance, load condition.
Oscillator Frequency/ External Synchronization
external resistor capacitor RTCT program MAX15004A/B/MAX15005A/B internal oscillator frequency from 15kHz 1MHz. MAX15004A/B output switching frequency one-half programmed oscillator frequency with maximum duty-cycle limit. MAX15005A/B output switching frequency same oscillator frequency. network connected RTCT controls both oscillator frequency maximum duty cycle. capacitor charges discharges from (0.1 VREG5) (0.55 VREG5). charges through discharges through internal trimmed controlled current sink. maximum duty cycle inversely proportional discharge time
Soft-Start
MAX15004/MAX15005 provided with externally adjustable soft-start function, saving number external components. 1.228V reference bypass connection MAX15004A/B/MAX15005A/B
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
(tDISCHARGE). Figures coarse selection capacitor values given switching frequency maximum duty cycle then following equations calculate resistor value fine-tune switching frequency verify worst-case maximum duty cycle.
CHARGE DMAX fOSC
MAX15004A/B maximum duty-cycle part, while MAX15005A/B 100% maximum duty-cycle part. fOUT MAX15004A/B fOUT fOSC MAX15005A/B. MAX15004A/B/MAX15005A/B synchronized using external clock SYNC input. proper frequency synchronization, SYNC's input frequency must least 102% programmed internal oscillator frequency. Connect SYNC SGND when using external clock. rising clock edge SYNC interpreted synchronization input. SYNC signal lost, internal oscillator takes control switching rate, returning switching frequency that network connected RTCT. This maintains output regulation even with intermittent SYNC signals.
WITHOUT SYNC INPUT
MAX15004/MAX15005
fOSC
tDISCHARGE
CHARGE 2.25(V) (1.33 3.375(V)
.Use This Equation fOSC 500kHz CHARGE tDISCHARGE fOSC .Use This Equation fOSC 500kHz CHARGE tDISCHARGE 160ns
where fOSC oscillator frequency, resistor connected from RTCT REG5, capacitor connected from RTCT SGND. Verify that oscillator frequency value meets target. Above calculations could repeated fine-tune switching frequency.
MAX15004A/B (DMAX 50%)
WITH SYNC INPUT
RTCT CLKINT SYNC
MAX15005A/B (DMAX 81%)
WITH SYNC INPUT
WITHOUT SYNC INPUT
RTCT CLKINT SYNC 81.25%
Figure Timing Diagram Internal Oscillator External SYNC DMAX Behavior
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
MAX15005 MAXIMUM DUTY CYCLE OUTPUT FREQUENCY (fOUT)
MAXIMUM DUTY CYCLE OUTPUT FREQUENCY (kHz) 1000 1000pF 560pF 220pF 1000 3300pF 2200pF 1500pF 100pF OSCILLATOR FREQUENCY (kHz) 1000 100pF 220pF 560pF 1000pF 1500pF 2200pF 3300pF
OSCILLATOR FREQUENCY (fOSC) RT/CT
Figure MAX15005 Maximum Duty Cycle Output Frequency.
Figure Oscillator Frequency RT/CT
n-Channel MOSFET Driver
drives gate external n-channel MOSFET. driver powered internal regulator (VCC), internally approximately 7.4V. external voltage higher than 7.4V applied 10V), appears peak gate drive voltage. regulated voltage keeps voltage below maximum gate voltage rating external MOSFET. source 750mA sink 1000mA peak current. average current sourced depends switching frequency total gate charge external MOSFET.
Slope Compensation
MAX15004A/B/MAX15005A/B internal ramp generator slope compensation. internal ramp signal resets beginning each cycle slews rate programmed external capacitor connected SLOPE. amount slope compensation needed depends downslope current waveform. Adjust MAX15004A/B/MAX15005A/B slew rate 110mV/µs using following equation: Slope compensation CSLOPE
Error Amplifier
MAX15004A/B/MAX15005A/B include internal error amplifier. noninverting input error amplifier connected internal 1.228V reference feedback provided inverting input. High 100dB open-loop gain 1.6MHz unity-gain bandwidth allow good closed-loop bandwidth transient response. Moreover, source sink current capability provides fast error correction during output load transient. Figure calculate powersupply output voltage using following equation: VOUT VREF where VREF 1.228V. amplifier's noninverting input internally connected soft-start circuit that gradually increases reference voltage during startup. This forces output voltage come orderly well-defined manner under load conditions.
where CSLOPE external capacitor SLOPE farads.
Current Limit
current-sense resistor (RCS), connected between source MOSFET ground, sets current limit. input voltage trip level 305mV. current-sense threshold accuracy. current-limit threshold higher than peak switch current rated output power minimum input voltage. following equation calculate value IPRI where IPRI peak current that flows through MOSFET full load minimum VIN.
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
When voltage produced this current (through current-sense resistor) exceeds current-limit comparator threshold, MOSFET driver (OUT) quickly terminates on-cycle. most cases, short-time constant filter required filter leadingedge spike sense waveform. amplitude width leading edge depends gate capacitance, drain capacitance (including interwinding capacitance), switching speed (MOSFET turn-on time). time constant just long enough suppress leading edge. given design, measure leading spike highest input rated output load determine value filter. 305mV current-limit threshold reduces power dissipation current-sense resistor. current-limit threshold further reduced adding offset input from REG5 voltage. reduce current-limit threshold below 150mV cause noise issues. Figure value current-limit threshold (VCS-LOW), calculate value using following equation. 4.75 0.290 where:
Applications Information
Boost Converter
MAX15004A/B/MAX15005A/B configured step-up conversion. boost converter output back (see Figure that controller function even during cold-crank input voltage 2.5V). Schottky diode (DVIN) path avoid backfeeding input source. current-limiting resistor (RVCC) also needed from boost converter output depending upon boost converter output voltage. total current sink into must limited 30mA. equations following sections calculate inductor input capacitor IN), output capacitor OUT) when using converter boost operation.
MAX15004/MAX15005
Inductor Selection Boost Configuration Using following equation, calculate minimum inductor value that converter remains continuous mode operation minimum output current (IOMIN).
LMIN VIN2 fOUT VOUT IOMIN
REG5
VOUT VOUT
IOMIN (0.25
MAX15004A/B MAX15005A/B
0.3V CURRENT-LIMIT COMPARATOR
higher value IOMIN reduces required inductance; however, increases peak currents switching MOSFET inductor. IOMIN from full load current. forward voltage drop external Schottky diode, duty cycle, voltage drop across external switch. Select inductor with resistance with saturation current (ISAT) rating higher than peak switch current limit converter.
Figure Reducing Current-Sense Threshold
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
DVIN CREG5 0.1µF REG5 CVCC 4.7µF RTCT CVIN RVCC VOUT COUT
DVCC
MAX15004A/B MAX15005A/B
COMP SLOPE CSLOPE
PGND
Figure Application Schematic
Input Capacitor Selection Boost Configuration input current boost converter continuous ripple current input capacitor low. Calculate minimum input capacitor value maximum using following equations:
fOUT where: (VIN fOUT
capacitor discharge VESR contribution capacitor. Assume input capacitor ripple contribution (VESR) capacitor discharge (VQ) equal when using combination ceramic aluminum capacitors. During converter turn-on, large current drawn from input source especially high output input differential. MAX15004/MAX15005 provided with programmable soft-start, however, large storage capacitor input necessary avoid chattering finite hysteresis.
total voltage drop across external MOSFET plus voltage drop across inductor ESR. peak-to-peak inductor ripple current calculated above. portion input ripple
Output Capacitor Selection Boost Configuration boost converter, output capacitor supplies load current when main switch required output capacitance high, especially higher duty cycles. Also, output capacitor needs enough minimize voltage drop while supporting load current. following equations calculate output capacitor, specified output ripple. ripple values peak-to-peak.
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
DMAX COUT fOUT load current, portion ripple capacitor discharge, VESR contribution capacitor. DMAX maximum duty cycle minimum input voltage. combination low-ESR ceramic high-value, low-cost aluminum capacitors lower output ripple noise. Reverse-transfer capacitance charge (CRSS). On-resistance (RDS(ON)). Maximum drain-to-source voltage (VDS(MAX)). Maximum gate frequencies threshold voltage (VTH(MAX)). high switching, dynamic characteristics (parameters above list) that predict switching losses have more impact efficiency than RDS(ON), which predicts losses. includes capacitances associated with charging gate. VDS(MAX) selected MOSFET must greater than maximum output voltage setting plus diode drop. additional margin recommended spikes MOSFET drain inductance rectifier diode output capacitor path. addition, helps predict current needed drive gate selected operating frequency when internal driving MOSFET.
MAX15004/MAX15005
Calculating Power Loss Boost Converter MAX15004A/MAX15005A devices available thermally enhanced package dissipate 1.7W +70°C ambient temperature. total power dissipation package must limited that junction temperature does exceed absolute maximum rating +150°C maximum ambient temperature; however, Maxim recommends operating junction about +125°C better reliability.
average supply current (IDRIVE-GATE) required switch driver IDRIVE-GATE fOUT where total gate charge 7.4V, number available from MOSFET datasheet. supply current MAX15004A/B/MAX15005A/B dependent switching frequency. Typical Operating Characteristics find supply current ISUPPLY MAX15004A/B/MAX15005A/B given operating frequency. total power dissipation (PT) device supply current (ISUPPLY) current required drive switch (IDRIVEGATE) calculated using following equation. VINMAX (ISUPPLY IDRIVE GATE
Slope Compensation Boost Configuration MAX15004A/B/MAX15005A/B internal ramp generator slope compensation stabilize current loop when operating duty cycles above 50%. advisable some slope compensation even lower than duty cycle improve noise immunity. slope compensations should optimized because much slope compensation turn converter into voltage-mode control. amount slope compensation required depends downslope inductor current when main switch off. inductor downslope depends input output voltage differential boost converter, inductor value, switching frequency. Theoretically, compensation slope should equal inductor downslope; however, little higher than slope advised. following equation calculate required compensating slope (mc) boost converter:
(VOUT
MOSFET Selection Boost Converter MAX15004A/B/MAX15005A/B drive wide variety n-channel power MOSFETs. Since limits output peak gate-drive voltage more than 11V, (max) gate voltage-rated MOSFET used without additional clamp. Best performance, especially low-input voltages (5VIN), achieved with low-threshold n-channel MOSFETs that specify on-resistance with gate-source voltage (VGS) 2.5V less. When selecting MOSFET, parameters include: Total gate charge (Qg).
internal ramp signal resets beginning each cycle slews rate programmed external capacitor connected SLOPE. Adjust MAX15004A/B/MAX15005A/B slew rate 110mV/µs using following equation: CSLOPE mc(mV
where CSLOPE external capacitor SLOPE farads.
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
Selecting Resistor (RVCC) external supply series resistor should sized provide enough average current from VOUT drive external MOSFET (IDRIVE) ISUPPLY. clamped internally 10.4V capable sinking 30mA current. resistor must high enough limit sink current below 30mA highest output voltage. Maintain voltage while feeding power from VOUT VCC. regulated output voltage VOUT, calculate RVCC using following equation:
RVCC (VOUT (ISUPPLY IDRIVE able with discontinuous mode flyback topology using MAX15004/MAX15005 automotive applications.
Transformer Design Step-by-step transformer specification design discontinuous flyback example explained below.
Follow steps below discontinuous mode transformer: Step Calculate secondary winding inductance guaranteed core discharge within minimum off-time. Step Calculate primary winding inductance sufficient energy support maximum load. Step Calculate secondary bias winding turns ratios. Step Calculate current primary estimate secondary current. Step Consider proper sequencing windings transformer construction leakage. Step discussed earlier, core must discharged during off-cycle discontinuous mode operation. secondary inductance determines time required discharge core. following equations calculate secondary inductance:
Figure Power Dissipation section values ISUPPLY IDRIVE.
Flyback Converter
choice conversion topology first stage power-supply design. topology selection criteria include input voltage range, output voltage, peak currents primary secondary circuits, efficiency, form factor, cost. output power less than input voltage range with small form factor requirements, flyback topology best choice. uses minimum components, thereby reducing cost form factor. flyback converter designed operate either continuous discontinuous mode operation. discontinuous mode operation, transformer core completes energy transfer during off-cycle, while continuous mode operation, next cycle begins before energy transfer complete. discontinuous mode operation chosen present example following reasons: maximizes energy storage magnetic component, thereby reducing size. Simplifies dynamic stability compensation design right-half plane zero). Higher unity-gain bandwidth. major disadvantage discontinuous mode operation higher peak-to-average current ratio primary secondary circuits. Higher peak-to-average current means higher current, therefore, higher loss lower efficiency. low-power converters, advantages using discontinuous mode easily surpass possible disadvantages. Moreover, drive capability MAX15004/MAX15005 good enough drive large switching MOSFET. With presently available MOSFETs, power output easily achiev18
(VOUT (DOFFMIN
IOUT fOUT(MAX)
DOFF
where: DOFFMIN minimum DOFF. secondary diode forward voltage drop. IOUT maximum output rated current. Step rising current primary builds energy stored core during on-time, which then released deliver output power during off-time. Primary inductance then calculated store enough energy during on-time support maximum output power.
DMAX INMIN POUT fOUT(MAX)
DMAX Maximum
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
Step Calculate secondary primary turns ratio (NSP) bias winding primary turns ratio (NBP) using following equations: 11.7 BIAS VOUT 0.35 forward bias drops secondary diode bias rectifier diode assumed 0.35V 0.7V, respectively. Refer diode manufacturer's datasheet verify these numbers. Step transformer manufacturer needs current maximum values primary, secondary, bias windings design wire diameter different windings. only wires with diameter smaller than 28AWG keep skin effect losses under control. achieve required copper cross-section, multiple wires must used parallel. Multifilar windings common high-frequency converters. Maximum currents primary secondary occur duty cycle (minimum input voltage) maximum output power. following equations calculate primary secondary currents: IPRMS ISRMS POUT DMAX DMAX VINMIN IOUT DOFFMAX DOFFMAX spike. MOSFET's absolute maximum rating must higher than worst-case (maximum input voltage output load) drain voltage. VDSMAX VINMAX (VOUT VSPIKE Lower maximum requirement means shorter channel, lower RDS-ON, lower gate charge, smaller package. lower NP/NS ratio allows VDSMAX specification keeps leakage inductance spike under control. resistor/diode/capacitor snubber network also used suppress leakage inductance spike. losses MOSFET calculated using value primary maximum current. Switching losses MOSFET depend operating frequency, total gate charge, transition loss during turn-off. There transition losses during turn-on since primary current starts from zero discontinuous conduction mode. MOSFET derating necessary avoid damage during system turn-on other fault conditions. following equation estimate power dissipation power MOSFET: PMOS (1.4 RDSON I2PRMS fOUTMAX INMAX OUTMAX fOUTMAX where: Total gate charge MOSFET 7.4V Input voltage tOFF Turn-off time Drain-to-source capacitance
MAX15004/MAX15005
bias current most MAX15004/MAX15005 applications about 20mA selection wire depends more convenience than current capacity. Step winding technique windings sequence important reduce leakage inductance spike switch turn-off. example, interleave secondary between primary halves. Keep bias winding close secondary, that bias voltage tracks output voltage.
MOSFET Selection MOSFET selection criteria include maximum drain voltage, peak/RMS current primary maximum-allowable power dissipation package without exceeding junction temperature limits. voltage seen MOSFET drain input voltage, reflected secondary voltage through transformer turns ratio leakage inductance
Output Filter Design output capacitance requirements flyback converter depend peak-to-peak ripple acceptable load. output capacitor supports load current during switch on-time. During off-cycle, transformer secondary discharges core replenishing lost charge simultaneously supplies load current. output ripple voltage drop charge loss during switch on-time output capacitor. high switching frequency MAX15004/MAX15005 reduces capacitance requirement.
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
additional small filter necessary suppress remaining low-energy high-frequency spikes. filter also helps attenuate switching frequency ripple. Care must taken avoid compensation problems insertion additional filter. Design filter with corner frequency more than decade higher than estimated closed-loop, unity-gain bandwidth minimize effect phase margin. 10µF low-ESR ceramic capacitors calculate inductance using following equation:
above. Lower ripple current means lower peak currents lower losses. higher inductance value needed lower ripple current means larger-sized inductor, which more expensive solution. inductors independent, however, winding them same core reduces ripple currents. Calculate maximum duty cycle using following equation choose values accordingly given switching frequency (see Oscillator Frequency/External Synchronization section). VOUT DMAX VIN-MIN VOUT (VDS where forward voltage Schottky diode, (0.305V) current-sense threshold MAX15004/MAX15005, voltage drop across switching MOSFET during on-time.
where estimated converter closed-loop unity-gain frequency.
SEPIC Converter
MAX15004A/B/MAX15005A/B configured SEPIC conversion when output voltage must lower higher than input voltage when input voltage varies through operating range. dutycycle equation: indicates that output voltage lower than input duty cycle lower than while VOUT higher than input duty cycle higher than 0.5. inherent advantage SEPIC topology over boost converter complete isolation output from source during fault output. MAX15004/MAX15005, SEPIC converter output back (Figure that controller function even during cold-crank input voltage 2.5V). Schottky diode (DVIN) path avoid backfeeding input source. current-limiting resistor (RVCC) also needed from output depending upon converter output voltage. total current sink must limited 25mA. Selecting Resistor (RVCC) section calculate optimum value resistor. SEPIC converter design includes sizing inductors, MOSFET, series capacitance, rectifier diode. inductance determined allowable ripple current through components mentioned
Inductor Selection SEPIC Converter following equations calculate inductance values. Assume both equal that inductor ripple current (IL) equal input current nominal input voltage calculate inductance value.
DMAX IN-MIN fOUT IOUT -MAX DMAX DMAX where fOUT converter switching frequency targeted system efficiency. coupled inductors MSD-series from Coilcraft PF0553-series from Pulse Engineering, Inc. Make sure inductor saturating current rating (ISAT) higher than peak inductor current calculated using following equation. current-sense resistor calculated based ILPK value from equation below (see Current Limit section). DMAX ILPK -MAX IOUT -MAX DMAX
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
MOSFET, Diode, Series Capacitor Selection SEPIC Converter SEPIC configuration, choose n-channel MOSFET with rating least higher than output input voltages. When operating high switching frequency, gate charge switching losses become significant. gatecharge MOSFETs. current MOSFET
series capacitor should chosen minimum ripple voltage (VCP) across capacitor. recommend using maximum ripple minimum input voltage (VIN-MIN) when operating minimum input voltage. multilayer ceramic capacitor series recommended their high ripple current capability ESR. following equation calculate series capacitor value. DMAX -MAX fOUT where 0.05 VIN-MIN. further discussion SEPIC converters,
MAX15004/MAX15005
IMOS -RMS
(ILPK (ILDC (ILPK ILDC
where ILDC (ILPK IL). Schottky diodes higher conversion efficiency. reverse voltage rating Schottky diode must higher than maximum input voltage (VIN-MAX) output voltage. Since average current flowing through diode equal output current, choose diode with forward current rating IOUT-MAX. current sense (RS) calculated using current-limit threshold (0.305V) MAX15004/MAX15005 ILPK. diode with forward current rating more than maximum output current limit SEPIC converter needs output short-circuit protected. 0.305 ILPK
Power Dissipation
MAX15004/MAX15005 maximum power dissipation depends thermal resistance from ambient environment ambient temperature. thermal resistance depends device package, copper area, other thermal mass, airflow. Calculate temperature rise using following equation: where junction-to-case thermal impedance (3°C/W) 16-pin TSSOP-EP package power dissipated device. Solder exposed package large copper area spread heat through board surface, minimizing case-toambient thermal impedance. Measure temperature copper area near device (TC) worst-case condition power dissipation 3°C/W thermal impedance. case-to-ambient thermal impedance (JA) dependent well heat transferred from ambient. large copper area keep temperature low. 38°C/W TSSOP16-EP 90°C/W TSSOP-16 package with condition specified JEDEC51 standard multilayer board.
Select below value calculated above. Calculate output current limit using following equation: IOUT -LIM (ILPK where duty cycle highest input voltage (VIN-MAX).
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
2.5V 7.5µH STP745G LL4148 100nF CVCC VOUT BAT54C 22µF 6.8µF 6.8µF 6.8µF 22µF 22µF VOUT (8V/2A)
6.8µF
MAX15005A/B
ON/OFF STD20NF06L
PGND CSLOPE 47pF REG5 SLOPE
REG5
REG5
150pF
N.C. RTCT 100pF
0.025
SGND 1.8k 47nF VOUT 680pF
SYNC RSYNC SYNC
COMP
150nF
2.7k
Figure SEPIC Application Circuit
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
Layout Recommendations
Typically, there sources noise emission switching power supply: high di/dt loops high dv/dt surfaces. example, traces that carry drain current often form high di/dt loops. Similarly, heatsink MOSFET connected device drain presents dv/dt source; therefore, minimize surface area heatsink much possible. Keep traces carrying switching currents short possible minimize current loops. ground plane best results. Careful layout critical achieve switching losses clean, stable operation. Refer MAX15005 data sheet specific layout example. multilayer board whenever possible better noise immunity. Follow these guidelines good layout: large copper plane under package solder exposed pad. effectively this copper area heat exchanger between ambient, expose this copper area bottom side PCB. connect connection from SGND (pin copper plane underneath midlayer-1 SGND plane when using multilayer board. Isolate power components high-current path from sensitive analog circuitry. Keep high-current paths short, especially ground terminals. This practice essential stable, jitter-free operation. Connect SGND PGND together close device return terminal bypass capacitor. connect them together anywhere else. Keep power traces load connections short. This practice essential high efficiency. thick copper PCBs (2oz 1oz) enhance fullload efficiency. Ensure that feedback connection short direct. Route high-speed switching nodes away from sensitive analog areas. internal layer SGND shield keep radiated noise away from device, feedback dividers, analog bypass capacitors. Connect SYNC SGND when used.
MAX15004/MAX15005
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
Typical Operating Circuits
(5.5V 16V) 220pF VANODE (110V/55mA) 10µF 200V 100k VGRID (60V/12mA) 22µF FILAMENT+ (3V/650mA) ON/OFF FILAMENTC17 2.2µF 330µF 6.3V
330µF
4700pF 100V 0.1µF
2200pF 100V
100k 47.5k
MAX15005A/B
182k 12.1k
PGND
100pF 8.45k 1200pF
REG5 SLOPE REG5 N.C. RTCT 560pF 0.06
REG5
SGND COMP 402k 0.1µF 4700pF VANODE 47pF 118k 1.3k
SYNC
Figure Flyback Application Circuit
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
Typical Operating Circuits (continued)
(4.5V 16V)
MAX15004/MAX15005
10µF
10µH/IHLP5050 VISHAY
0.1µF 301k 100k 153k VOUT
1µF/16V CERAMIC B340LB VOUT (18V/2A) 56µF/25V SVP-SANYO Si7886
MAX15005A/B
ON/OFF
PGND
100pF
REG5 SLOPE REG5 N.C. RTCT 100pF 0.025
REG5
180pF
SGND COMP 100k 0.1µF VOUT 330pF 136k
SYNC SYNC
0.1µF
Figure Boost Application Circuit
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
Configurations
VIEW
ON/OFF SLOPE N.C. RTCT SGND SYNC
PGND ON/OFF SLOPE N.C. RTCT SGND SYNC
PGND
MAX15004A MAX15005A
REG5 COMP
MAX15004B MAX15005B
REG5 COMP
TSSOP-EP
EXPOSED PAD.
TSSOP
Chip Information
PROCESS: BiCMOS
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
Package Information
(The package drawing(s) this data sheet reflect most current specifications. latest package outline information www.maxim-ic.com/packages.)
TSSOP4.40mm.EPS
PACKAGE OUTLINE, TSSOP 4.40mm BODY
MAX15004/MAX15005
21-0066
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers MAX15004/MAX15005
Package Information (continued)
(The package drawing(s) this data sheet reflect most current specifications. latest package outline information www.maxim-ic.com/packages.)
TSSOP 4.4mm BODY.EPS
4.5V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
Revision History
REVISION NUMBER REVISION DATE 1/07 11/07 Initial release Updated Features, revised equations pages revised Figure with correct MOSFET, updated package outline DESCRIPTION PAGES CHANGED
MAX15004/MAX15005
Maxim cannot assume responsibility circuitry other than circuitry entirely embodied Maxim product. circuit patent licenses implied. Maxim reserves right change circuitry specifications without notice time.
Maxim Integrated Products, Gabriel Drive, Sunnyvale, 94086 408-737-7600
2007 Maxim Integrated Products registered trademark Maxim Integrated Products, Inc.
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