Synchronous Buck DC-DC Linear Power Controller RT9259 dual-channe

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Synchronous Buck DC-DC Linear Power Controller RT9259 dual-channe

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RT9259
Synchronous Buck DC-DC Linear Power Controller
RT9259 dual-channel DC/DC controller specifically designed deliver high quality power where power source available. This part consists synchronous buck controller controller. synchronous buck controller integrates MOSFET drivers that support 12V+12V bootstrapped voltage high efficiency power conversion. bootstrap diode built-in simplify circuit design minimize external part count. controller drives external N-MOSFET lower power requirement. Other features include adjustable operation frequency, internal soft start, under voltage protection, over current protection shut down function. With above functions, this part provides customers compact, high efficiency, well-protected cost-effective solution. This part comes VQFN-16L 4x4, SOP14 SSOP-16 packages.
Features
Single Bias Supply Support Dual Channel Power Conversion Synchronous Rectified Buck Controller Linear Controller Both Controllers Drive Cost N-MOSFETs Adjustable Frequency from 150kHz 1MHz Free-Run Frequency 230kHz Small External Component Count Output Voltage Regulation Controller Accuracy Controller Accuracy Internal VREF Power Support Lower 0.8V Adjustable External Compensation Linear Controller Drives N-MOSFET Pass Transistor Fully-Adjustable Outputs Under Voltage Protection Both Outputs Over Current Fault Monitor MOSFET; Current Sense Resistor Required. RoHS Compliant 100% Lead (Pb)-Free
Ordering Information
RT9259 Package Type SOP-14 SSOP-16 VQFN-16 (V-Type)
Operating Temperature Range Free with Commercial Standard Green (Halogen Free with Commercial Standard)
Note Richtek Pb-free Green products RoHS compliant compatible with current requirements IPC/JEDEC J-STD-020. Suitable SnPb Pb-free soldering processes. 100% matte (Sn) plating.
Applications
Graphic Card GPU, Memory Core Power Graphic Card Interface Power Motherboard, Desktop Servers Chipset Memory Core Power Equipments Telecomm Equipments High Power DC-DC Regulators
Marking Information
marking information, contact sales representative directly through Richtek distributor located your area, otherwise visit website detail.
DS9259-03T00 August 2007
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RT9259
Configurations
(TOP VIEW)
RT_DIS BOOT UGATE PHASE
BOOT RT_DIS COMP
UGATE PHASE PGND LGATE VCC12
SOP-14
SSOP-16
VQFN-16L
Typical Application Circuit
+12V VIN1 +3.3V/+5V/+12V
RT9259
VIN2 +12V
BOOT VCC12
UGATE PHASE LGATE PGND
VOUT1 COUT
VOUT2 COUT2
RT_DIS
COMP
Functional Description
RT9259 RT9259 RT9259PQV BOOT Bootstrap supply upper gate driver. Connect bootstrap capacitor between BOOT PHASE pin. bootstrap capacitor provides charge turn upper MOSFET. Connect resistor from RT_DIS frequency. addition, this pulled down towards GND, will disable both regulator outputs until released. Buck converter external compensation. This used compensate control loop buck converter. Buck converter feedback voltage. This inverting input error amplifier. senses switcher output through external resistor divider network. Connect this gate external MOSFET. This provides drive linear regulator's pass MOSFET. Name Function
RT_DIS COMP
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DS9259-03T00 August 2007
VCC12
BOOT RT_DIS COMP
UGATE PHASE PGND LGATE VCC12 VCC12
COMP
PGND LGATE
continued
RT9259
RT9259 RT9259 RT9259PQV VCC12 Linear regulator feedback voltage. This inverting input error amplifier protection monitor. Connect this external resistor divider network linear regulator. Ground. Connect this well-decoupled bias supply. also positive supply lower gate driver, LGATE. Internal Connection. Lower gate driver output. Connect gate low-side power N-MOSFET. This monitored adaptive shoot-through protection circuitry determine when lower MOSFET turned off. Power ground return lower gate driver. Connect this source upper MOSFET drain lower MOSFET. This monitored adaptive shoot-through protection circuitry determine when upper MOSFET turned off. Connect this well-decoupled bias supply. also positive supply lower gate driver, LGATE. Name Function
Exposed (17) LGATE PGND PHASE
UGATE
Function Block Diagram
VCC12
Voltage Reference VREF2 VCC12 Inhibit 0.4V
Bias
Power Reset
Regulator
5VDD
Soft-Start Fault Logic ROCSET PH_M 0.4V 40uA
1.5V BOOT UGATE
Shutdown VREF1 Driver Logic
PHASE
RT_DIS
Oscillator
LGATE PGND
COMP
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RT9259
Absolute Maximum Ratings
(Note Supply Voltage, PHASE 200ns -10V BOOT PHASE BOOT -0.3V VCC+15V 200ns -0.3V UGATE VPHASE 0.3V VBOOT 0.3V LGATE 0.3V 0.3V 0.3V 0.3V Input, Output Voltage 0.3V Power Dissipation, 25°C SOP-14 1.000W SSOP-16 0.909W VQFN-16L 1.852W Package Thermal Resistance (Note SOP-14, 100°C/W SSOP-16, 110°C/W VQFN-16L 4x4, 54°C/W Junction Temperature 150°C Lead Temperature (Soldering, sec.) 260°C Storage Temperature Range -40°C 150°C Susceptibility (Note (Human Body Mode) (Machine Mode) 200V
Recommended Operating Conditions
(Note
Supply Voltage, Junction Temperature Range -40°C 125°C Ambient Temperature Range -40°C 85°C
Electrical Characteristics
(VCC 12V, 25°C unless otherwise specified)
Parameter Supply Input Power Supply Voltage Power Reset Power Reset Hysteresis Power Supply Current
Symbol
Test Conditions
Units
VVCCRTH VVCCHYS IVCC UGATE, LGATE Open Rising
-8.8
0.78
10.4
continued
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DS9259-03T00 August 2007
RT9259
Parameter Oscillator Free Running Frequency Ramp Amplitude Reference Voltage Error Amplifier Reference Linear Driver Reference Error Amplifier Gain Gain-Bandwidth Product Slew Rate Gate Driver Upper Drive Source Upper Drive Sink Lower Drive Source Lower Drive Sink Protection Under Voltage Protection Soft-Start Time Interval Over Current Threshold RT_DIS Shutdown Threshold Linear Regulator Output High Voltage Output Voltage Source Current Sink Current VDRV VDRV IDRVSR IDRVSC 10.3 VUVP 0.36 -0.35 -400 0.45 RUGATE RUGATE RLGATE RLGATE VBOOT VPHASE 12V, VBOOT VUGATE VUGATE VLGATE VLGATE CLOAD V/us VREF1 VREF2 0.792 0.784 0.808 0.816 fOSC 110k -300 -kHz Symbol Test Conditions Units
Note Stresses listed above "Absolute Maximum Ratings" cause permanent damage device. These stress ratings. Functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods remain possibility affect device reliability. Note Devices sensitive. Handling precaution recommended. Note device guaranteed function outside operating conditions. Note measured natural convection 25°C high effective 4-layers 2S2P thermal conductivity test board JEDEC 51-7 thermal measurement standard.
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RT9259
Typical Operating Characteristics
Dead Time
Load, Falling UGATE UGATE VIN1 PHASE VIN1 Load, Rising
Dead Time
PHASE
(5V/Div)
LGATE
(5V/Div)
LGATE
Time (25ns/Div)
Time (25ns/Div)
Power
Load UGATE
OUT1
(2V/Div)
(10V/Div)
(10V/Div)
LGATE
(0.5A/Div) (10A/Div) (200mV/Div)
Time (2.5ms/Div)
Time (5s/Div)
Shut Down
Full Load UGATE Load VIN1
Start
(20V/Div) (5V/Div)
LGATE RT_Dis
(10V/Div)
OUT1
(500mV/Div)
PHASE RT_Dis
(500mV/Div) (10V/Div) (1V/Div) (500mV/Div)
OUT1
Time (5s/Div)
Time (1ms/Div)
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DS9259-03T00 August 2007
RT9259
Start
Load ILOAD ILOAD
Start
(2.5A/Div)
RT_Dis
(500mV/Div)
OUT1
(500mV/Div)
(500mV/Div) Time (1ms/Div)
OUT1
Time (1ms/Div)
Transient Response
Transient Response
UGATE
(20V/Div) (100mV/Div)
VOUT1
(100mV/Div)
(20V/Div)
UGATE
(10A/Div)
VIN1 12V, VOUT1 ILOAD
(10A/Div)
VIN1 12V, VOUT1 ILOAD
Time (2.5s/Div)
Time (10s/Div)
Transient Response
VIN2 12V, VOUT2 2.5V ILOAD 100mA LGATE
Under Voltage Protection
VIN2
(2mV/Div)
OUT2
(10V/Div)
UGATE
(20V/Div)
COMP
(500mV/Div) (0.5A/Div) (1V/Div) Time (100s/Div)
OUT2
Time (10ms/Div)
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RT9259
Application Information
Introduction RT9259 dual-channel DC/DC controller specifically designed deliver high quality power where power source available. This part consists synchronous buck controller controller. synchronous buck controller integrates internal MOSFET drivers that support 12V+12V bootstrapped voltage high efficiency power conversion. bootstrap diode built-in simplify circuit design minimize external part count. controller drives external N-MOSFET lower power requirement. Internal 5VDD Regulator highly recommended power RT9259 with welldecoupled VCC12 pin. VCC12 powers RT9259 control circuit, side gate driver bootstrap circuit high side gate driver. bootstrap diode embedded facilitates design reduce total cost. external Schottky diode required. RT9259 integrates MOSFET gate drives that powered from VCC12 support driving capability. Converters that consist RT9259 feature high efficiency without special consideration selection MOSFETs. internal linear regulator regulates VCC12 input 5VDD voltage internal control logic circuit. external bypass capacitor required filtering 5VDD voltage. This further facilitates design reduces total cost. Power Reset RT9259 automatically initializes upon applying input power VCC12) pin. power reset function (POR) continually monitors input bias supply voltage VCC12 pin. VCC12V level typically 9.6V VCC12V rising. Frequency Setting Shut Down Connecting resistor from RT_DIS sets operation frequency. relation roughly expressed equation.
fOSC 230kHz 7700 (kHz)
When open, free running frequency 230kHz typically. Figure shows operation frequency quick reference.
1400 1200 1000
(kHz)
1000
(kohm)
Figure Frequency Shorting RT_DIS with external signallevel MOSFET shuts down device. This allows flexible power sequence control specified application. RT_DIS threshold voltage 0.4V typically. VIN1 Detection RT9259 continuously generates 10kHz pulse train with pulse width turn upper MOSFET detecting existence VIN1 after VCC12V RT_DIS enabled shown Figure PHASE voltage monitored during detection duration. PHASE voltage crosses 1.5V four times, VIN1 existence recognized RT9259 initiates soft start cycle described next section.
VIN1 POR_H PHASE_M
1.5V
PHASE UGATE PHASE waveform Internal Counter will count (VPHASE 1.5V) four times (rising falling) recognize VIN1 ready.
Figure
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DS9259-03T00 August 2007
RT9259
Soft Start Synchronous Buck Converter built-in soft-start used prevent surge current from power supply input during power (referring Functional Block Diagram). error amplifier threeinput device. VREF1 whichever smaller dominates behavior non-inverting input. internal soft start voltage linearly ramps about after VIN1 existence recognized with about delay. According, output voltage ramps smoothly target level. rise time output voltage about shown Figure VREF1 takes over behavior when VREF1. also used soft start. input voltage VIN2 MUST ready before starts ramp Otherwise function triggered shut down RT9259.
LGATE (10V/Div) UGATE (20V/Div) RT_DIS (500mV/Div) UGATE (20V/Div) VOUT1 (500mV/Div) LGATE (10V/Div) COMP (500mV/Div) VOUT1 (1V/Div) Time (10ms/Div) Time (1ms/Div) UGATE (20V/Div)
VIN1
(500mV/Div)
VOUT (20V/Div) Time (10ms/Div)
Figure triggered
VIN2
Figure hiccups triggered Over Current Protection RT9259 senses current flowing through lower MOSFET over current protection (OCP) sensing PHASE voltage shown Functional Block Diagram. 40uA current source flows through internal ROCSET PHASE causes 0.8V voltage drop across resistor. triggered voltage PHASE (drop lower MOSFET VDS) lower than -0.4V when side MOSFET conducting. Accordingly inductor current threshold function conducting resistance lower MOSFET RDS(ON)
IOCSET OCSET (20k 0.4V 0.4V RDS(ON) RDS(ON)
Figure Start RT_DIS Under Voltage Protection voltages monitored under voltage protection (UVP) after soft start completed. triggered feedback voltages under (50% VREFX) with 30us delay. shown Figure RT9259 controller shut down when drops lower than threshold. Figure RT9259 shuts down after time hiccups triggered FBL.
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RT9259
MOSFET with RDS(ON) used, threshold current about 25A. Once triggered, RT9259 enters hiccup mode re-soft starts again. RT9259 shuts down after time hiccups. well-designed compensator regulates output voltage reference voltage VREF with fast transient response good stability. order achieve fast transient response accurate output regulation, adequate compensator design necessary. goal compensation network provide adequate phase margin (greater than degrees) highest crossing frequency. also recommended manipulate loop frequency response that gain crosses over slope -20dB/dec.
Driver Driver PHASE COUT COMP
Inductor Current (20A/Div)
VOSC
Comparator
VOUT
Time (2.5ms/Div)
Figure Shorted then Start
(20A/Div)
VOUT
LGATE (5V/Div) UGATE (5V/Div)
COMP
Time (5s/Div)
Figure Shorted then Start (Extended Figure Feedback Compensation RT9259 voltage mode controller. control loop single voltage feedback path including compensator modulator shown Figure modulator consists comparator power stage. comparator compares error amplifier output (COMP) with oscillator (OSC) sawtooth wave provide pulsewidth modulated (PWM) with amplitude PHASE node. wave smoothed output filter LOUT COUT. output voltage (VOUT) sensed inverting input error amplifier.
Figure Closed Loop Modulator Frequency Equations modulator transfer function small-signal transfer function VOUT/VCOMP (output voltage over error amplifier output. This transfer function dominated gain, double pole, zero shown Figure gain modulator input voltage (VIN) divided peak peak oscillator voltage VOSC. output filter introduces double pole, 40dB/decade gain slope above corner resonant frequency, total phase degrees. resonant frequency filter expressed
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RT9259
zero contributed associated with output capacitance. Note that this requires that output capacitor should have enough satisfy stability requirements. zero output capacitor expressed follows fESR COUT Compensation Frequency Equations compensation network consists error amplifier impedance networks shown Figure
VOUT
often jeopardize system stability. order cancel filter poles, place zero before filter resonant frequency. experience, place zero filter resonant frequency. Crossover frequency should higher than zero less than switching frequency. second pole placed half switching frequency. Thermal Considerations continuous operation, exceed absolute maximum operation junction temperature 125°C. maximum power dissipation depends thermal resistance package, layout, rate surroundings airflow temperature difference between junction ambient. maximum power dissipation calculated following formula PD(MAX) TJ(MAX)
COMP VREF
Where J(MAX) maximum operation junction temperature 125°C, ambient temperature junction ambient thermal resistance. recommended operating conditions specification RT9259, where J(MAX) maximum junction temperature (125°C) maximum ambient temperature. junction ambient thermal resistance layout dependent. VQFN-16L packages, thermal resistance 54°C/W standard JEDEC 51-7 four-layers thermal test board. maximum power dissipation 25°C calculated following formula
Compensation Gain
Figure Compensation Loop
Loop Gain
Gain (dB)
PD(MAX) 125°C 25°C 54°C/W 1.852 QFN-16L packages PD(MAX) 125°C 25°C) 100°C/W 1.000 SOP-14 packages PD(MAX) 125°C 25°C 110°C/W 0.909 SSOP-16 packages
Modulator Gain
-4040
-6060 10db(vo)
2100l d(op)
Feuny rqec Frequency (Hz)
100k
Figure Bode Plot Figure shows DC-DC converter's gain frequency. compensation gain uses external impedance networks provide stable, high bandwidth loop. High crossover frequency desirable fast transient response,
maximum power dissipation depends operating ambient temperature fixed (MAX) thermal resistance RT9259 packages, Figure derating curves allows designer effect rising ambient temperature maximum power allowed.
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RT9259
Maximum Power Dissipation
4-Layers QFN-16L
1.75 1.25 0.75 0.25
SOP-14
SSOP-16
power components controller should placed firstly. Place input capacitors, especially high-frequency ceramic decoupling capacitors, close power switches. Place output inductor output capacitors between MOSFETs load. Also locate controller near MOSFETs. multi-layer printed circuit board recommended. Figure shows connections critical components converter. Note that capacitors COUT each them represents numerous physical capacitors. dedicated grounding plane vias ground critical components this layer. Apply another solid layer power plane this plane into smaller islands common voltage levels. power plane should support input power output power nodes. copper filled polygons bottom circuit layers PHASE node, necessary oversize this particular island. Since PHASE node subjected very high dV/dt voltages, stray capacitance formed between these islands surrounding circuitry will tend couple switching noise. remaining printed circuit layers small signal routing. traces between controller gate MOSFET also traces connecting source MOSFETs should sized carry peak currents.
5V/12V
Ambient Temperature (°C)
Figure Derating Curves RT9259 Packages Layout Considerations MOSFETs switch very fast efficiently. speed with which current transitions from device another causes voltage spikes across interconnecting impedances parasitic circuit elements. voltage spikes degrade efficiency radiate noise, that results over-voltage stress devices. Careful component placement layout printed circuit design minimize voltage spikes induced converter. Consider, example, turn-off transition upper MOSFET prior turn-off, upper MOSFET carrying full load current. During turn-off, current stops flowing upper MOSFET picked side MOSFET schottky diode. inductance switched current path generates large voltage spike during switching interval. Careful component selections, layout critical components, shorter wider traces help minimizing magnitude voltage spikes. There sets critical components DC-DC converter using RT9259. switching power components most critical because they switch large amounts energy, such, they tend generate equally large amounts noise. critical small signal components those connected sensitive nodes those supplying critical bypass current.
VOUT
LOAD
LGATE RT9259 UGATE
Figure connections critical components converter
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DS9259-03T00 August 2007
RT9259
Outline Dimension
Symbol
Dimensions Millimeters 8.534 3.810 1.346 0.330 1.194 0.178 0.102 5.791 0.406 8.738 3.988 1.753 0.508 1.346 0.254 0.254 6.198 1.270
Dimensions Inches 0.336 0.150 0.053 0.013 0.047 0.007 0.004 0.228 0.016 0.344 0.157 0.069 0.020 0.053 0.010 0.010 0.244 0.050
Lead Plastic Package
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RT9259
Symbol
Dimensions Millimeters 1.346 0.102 1.499 0.203 0.178 4.801 0.635 5.791 3.810 0.406 6.198 3.988 1.270 0.305 0.254 5.004 1.753 0.254
Dimensions Inches 0.053 0.004 0.059 0.008 0.007 0.189 0.025 0.228 0.150 0.016 0.244 0.157 0.050 0.012 0.010 0.197 0.069 0.010
16-Lead SSOP Plastic Package
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DS9259-03T00 August 2007
RT9259
DETAIL
DETAIL Mark Options Note configuration identifier optional, must located within zone indicated.
Symbol
Dimensions Millimeters 0.800 0.000 0.175 0.250 3.950 2.000 3.950 2.000 0.650 0.500 0.600 1.000 0.050 0.250 0.380 4.050 2.450 4.050 2.450
Dimensions Inches 0.031 0.000 0.007 0.010 0.156 0.079 0.156 0.079 0.026 0.020 0.024 0.039 0.002 0.010 0.015 0.159 0.096 0.159 0.096
V-Type Package
Richtek Technology Corporation
Headquarter Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
Richtek Technology Corporation
Taipei Office (Marketing) 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com
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Synchronous Buck DC-DC Linear Power Controller RT9259 dual-channe

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