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4684 Advanced Triple Linear Power Controller HIP6021 provide
Top Searches for this datasheetHIP6021 4684 Advanced Triple Linear Power Controller HIP6021 provides power control protection four output voltages high-performance, graphics intensive microprocessor computer applications. integrates voltage-mode controller three linear controllers, well monitoring protection functions into 28-pin SOIC package. controller regulates microprocessor core voltage with synchronous-rectified buck converter. linear controllers regulate computer system's 1.5V 3.3V power, 1.5V power, 1.8V power North/South Bridge core voltage and/or cache memory circuits. HIP6021 includes Intel-compatible, 5-input digital-to-analog converter (DAC) that adjusts core output voltage from 1.3VDC 2.05VDC 0.05V steps from 2.1VDC 3.5VDC 0.1V increments. precision reference voltage-mode control provide static regulation. power linear controller's output (VOUT2) user-selectable, through TTL-compatible signal applied SELECT pin, levels 1.5V 3.3V with accuracy. Based status pin, other linear regulators provide either fixed output voltages 1.5V±3% (VOUT3) 1.8V±3% (VOUT4), user-adjustable means external resistor divider. linear controllers employ either N-channel MOSFETs bipolar NPNs pass transistor. HIP6021 monitors output voltages. single Power Good signal issued when core within ±10% setting other outputs above their undervoltage levels. Additional built-in over-voltage protection core output uses lower MOSFET prevent output voltages above 115% setting. controller's over-current function monitors output current using voltage drop across upper MOSFET's rDS(ON). Features Provides Regulated Voltages Microprocessor Core, Bus, Memory, Power Drives N-Channel MOSFETs Linear Regulator Drives Compatible with both MOSFET Bipolar Series Pass Transistors Fixed Externally Resistor-Adjustable Linear Outputs (FIX Pin) Simple Single-Loop Control Design Voltage-Mode Control Fast Converter Transient Response High-Bandwidth Error Amplifier Full 100% Duty Ratio Excellent Output Voltage Regulation Core Output: Over Temperature Other Outputs: Over Temperature TTL-Compatible 5-Bit Microprocessor Core Output Voltage Selection Wide Range 1.3VDC 3.5VDC Power-Good Output Voltage Monitor Over-Voltage Over-Current Fault Monitors Switching Regulator Does Require Extra Current Sensing Element, Uses MOSFET's rDS(ON) Small Converter Size Constant Frequency Operation 200kHz Free-Running Oscillator; Programmable From 50kHz Over 1MHz Small External Component Count Pinout HIP6021 (SOIC) VIEW DRIVE2 UGATE PHASE LGATE PGND OCSET VSEN1 COMP VSEN3 DRIVE3 VAUX DRIVE4 Ordering Information PART NUMBER HIP6021CB HIP6021EVAL1 TEMP. RANGE (oC) PACKAGE SOIC PKG. M28.3 VID4 VID3 VID2 VID1 Evaluation Board VID0 PGOOD Applications Motherboard Power Regulation Computers VSEN2 SELECT FAULT/RT VSEN4 2-296 CAUTION: These devices sensitive electrostatic discharge; follow proper Handling Procedures. http://www.intersil.com 407-727-9207 Copyright Intersil Corporation 1999 Block Diagram VSEN3 VSEN1 OCSET VAUX POWER-ON 1.10 RESET (POR) 200µA DRIVE4 0.90 0.75 1.15 1.26V VSEN4 HIP6021 VSEN2 ERROR AMP1 0.75 OSCILLATOR SELECT 1.5V 3.3V DRIVE2 LINEAR UNDERVOLTAGE SOFTINHIBIT START FAULT FAULT LOGIC 2-297 DRIVE1 DRIVE3 VAUX PGOOD UGATE PHASE GATE CONTROL COMP1 PWM1 LGATE 28µA DACOUT SYNCH DRIVE CONVERTER (DAC) 4.5V PGND FAULT COMP VID0 VID1 VID2 VID4 VID3 HIP6021 Simplified Power System Diagram +5VIN +3.3VIN LINEAR CONTROLLER VOUT2 CONTROLLER VOUT1 HIP6021 VOUT3 LINEAR CONTROLLER LINEAR CONTROLLER VOUT4 Typical Application +12VIN +5VIN OCSET +3.3VIN PGOOD DRIVE2 UGATE VSEN2 PHASE LOUT1 VOUT1 1.3V 3.5V POWERGOOD VOUT2 1.5V 3.3V COUT2 LGATE PGND TYPEDET SELECT VSEN1 VAUX COUT1 HIP6021 VOUT3 1.5V DRIVE3 VSEN3 COMP COUT3 FAULT VID0 VOUT4 1.8V DRIVE4 VSEN4 VID1 VID2 VID3 COUT4 VID4 2-298 HIP6021 Absolute Maximum Ratings Supply Voltage, +15V PGOOD, RT/FAULT, DRIVE, PHASE, GATE Voltage 0.3V 0.3V Input, Output Voltage -0.3V Classification Class Thermal Information Thermal Resistance (Typical, Note (oC/W) SOIC Package. Maximum Junction Temperature (Plastic Package) 150oC Maximum Storage Temperature Range -65oC 150oC Maximum Lead Temperature (Soldering 10s) 300oC (SOIC Lead Tips Only) Operating Conditions Supply Voltage, +12V ±10% Ambient Temperature Range 70oC Junction Temperature Range 125oC CAUTION: Stresses above those listed "Absolute Maximum Ratings" cause permanent damage device. This stress only rating operation device these other conditions above those indicated operational sections this specification implied. NOTE: measured with component mounted evaluation board free air. Electrical Specifications PARAMETER SUPPLY CURRENT Nominal Supply Current POWER-ON RESET Rising Threshold Falling Threshold Rising VAUX Threshold VAUX Threshold Hysteresis Rising VOCSET Threshold OSCILLATOR Free Running Frequency Total Variation Ramp Amplitude Recommended Operating Conditions, Unless Otherwise Noted. Refer Block Simplified Power System Diagrams, Typical Application Schematic SYMBOL TEST CONDITIONS UNITS UGATE, LGATE, DRIVE2, DRIVE3, DRIVE4 Open VOCSET 4.5V VOCSET 4.5V VOCSET 4.5V VOCSET 4.5V 1.26 10.4 FOSC VOSC OPEN 200k Open VP-P BANDGAP REFERENCE DAC(VID0-VID4) Input Voltage DAC(VID0-VID4) Input High Voltage DACOUT Voltage Accuracy Bandgap Reference Voltage Bandgap Reference Tolerance LINEAR REGULATORS (OUT2, OUT3, OUT4) Regulation (All Linears) VSEN2 Regulation Voltage VSEN2 Regulation Voltage VSEN3 Regulation Voltage VSEN4 Regulation Voltage Under-Voltage Level (VSEN/VREG) Under-Voltage Hysteresis (VSEN/VREG) Output Drive Current (All Linears) VREG2 VREG2 VREG3 VREG4 VSENUV VSEN Rising VSEN Falling VAUX-VDRIVE 0.6V SELECT 0.8V SELECT 2.0V -1.0 -2.5 1.265 +1.0 +2.5 2-299 HIP6021 Electrical Specifications PARAMETER Recommended Operating Conditions, Unless Otherwise Noted. Refer Block Simplified Power System Diagrams, Typical Application Schematic (Continued) SYMBOL TEST CONDITIONS UNITS SYNCHRONOUS CONTROLLER ERROR AMPLIFIER Gain Gain-Bandwidth Product Slew Rate CONTROLLER GATE DRIVER UGATE Source UGATE Sink LGATE Source LGATE Sink PROTECTION VSEN1 Over-Voltage (VSEN1/DACOUT) FAULT Sourcing Current OCSET1 Current Source Soft-Start Current POWER GOOD VSEN1 Upper Threshold (VSEN1/DACOUT) VSEN1 Under-Voltage (VSEN1/DACOUT) VSEN1 Hysteresis (VSEN1/DACOUT) PGOOD Voltage VPGOOD VSEN1 Rising VSEN1 Rising Upper/Lower Threshold IPGOOD -4mA IOVP IOCSET VSEN1 Rising VFAULT/RT 2.0V VOCSET 4.5VDC IUGATE RUGATE ILGATE RLGATE 12V, VUGATE VGATE-PHASE 12V, VLGATE VLGATE GBWP COMP 10pF V/µs Typical Performance Curves CUGATE1 CUGATE2 CLGATE1 1000 RESISTANCE PULLUP +12V (mA) 3600pF 4800pF 1500pF PULLDOWN 660pF SWITCHING FREQUENCY (kHz) 1000 SWITCHING FREQUENCY (kHz) 1000 FIGURE RESISTANCE FREQUENCY FIGURE BIAS SUPPLY CURRENT FREQUENCY 2-300 HIP6021 Functional Descriptions (Pin Provide bias supply this pin. This also provides gate bias charge MOSFETs controlled voltage this monitored Power-On Reset (POR) purposes. soft-start capacitor, disabling outputs. Dedicated internal circuitry insures core output voltage does negative during this process. When re-enabled, undergoes soft-start cycle. Left open, this pulled internal pull-down resistor, enabling operation. (Pin Grounding this bypasses internal resistor dividers that output voltage 1.5V 1.8V linear regulators. This way, output voltage regulators adjusted from 1.26V input voltage (+3.3V +5V) external resistor divider connected corresponding VSEN pin. output voltage external resistor divider determined using following formula: 1.265V (Pin Signal ground voltage levels measured with respect this pin. PGND (Pin This power ground connection. synchronous converter's lower MOSFET source this pin. VAUX (Pin This provides boost current linear regulators' output drives event bipolar transistors (instead N-channel MOSFETs) employed pass elements. voltage this monitored power-on reset (POR) purposes. where ROUT resistor connected from VSEN output regulator, RGND resistor connected from VSEN ground. Left open, pulled high, enabling fixed output voltage operation. (Pin Connect capacitor from this ground. This capacitor, along with internal 28µA current source, sets soft-start interval converter. VID0, VID1, VID2, VID3, VID4 (Pins VID0-4 TTL-compatible input pins 5-bit DAC. logic states these five pins program internal voltage reference (DACOUT). level DACOUT sets microprocessor core converter output voltage, well coresponding PGOOD thresholds. FAULT (Pin This provides oscillator switching frequency adjustment. placing resistor (RT) from this GND, nominal 200kHz switching frequency increased according following equation: 200KHz OCSET (Pin Connect resistor from this drain respective upper MOSFET. This resistor, internal 200µA current source, upper MOSFET's on-resistance converter over-current trip point. over-current trip cycles soft-start function. voltage this monitored power-on reset (POR) purposes pulling this with open drain device will shutdown GND) Conversely, connecting resistor from this reduces switching frequency according following equation: 200KHz 12V) PHASE (Pin Connect PHASE converter's upper MOSFET source. This represents gate drive return current path used monitor voltage drop across upper MOSFET over-current protection. Nominally, voltage this 1.26V. event over-voltage over-current condition, this internally pulled VCC. PGOOD (Pin PGOOD open collector output used indicate status output voltages. This pulled when synchronous regulator output within ±10% DACOUT reference voltage when other outputs below their under-voltage thresholds. PGOOD output open `11111' code. UGATE (Pin Connect UGATE converter's upper MOSFET gate. This provides gate drive upper MOSFET. LGATE (Pin Connect LGATE converter's lower MOSFET gate. This provides gate drive lower MOSFET. (Pin This shuts down outputs. TTL-compatible, logic level high signal applied this immediately discharges COMP (Pin COMP available external pins converter error amplifier. inverting input 2-301 HIP6021 error amplifier. Similarly, COMP error amplifier output. These pins used compensate voltage-mode control feedback loop synchronous converter. either output voltage achieved applying proper logic level SELECT pin. remaining linear controllers supply 1.5V power (VOUT3) 1.8V memory power (VOUT4). linear controllers designed employ external pass transistor. VSEN1 (Pin This connected converter's output voltage. PGOOD comparator circuits this signal report output voltage status over- voltage protection. Initialization HIP6021 automatically initializes upon receipt input power. Special sequencing input supplies necessary. Power-On Reset (POR) function continually monitors input supply voltages. monitors bias voltage (+12VIN) pin, input voltage (+5VIN) OCSET pin, 3.3V input voltage (+3.3VIN) VAUX pin. normal level OCSET equal +5VIN less fixed voltage drop (see over-current protection). function initiates soft-start operation after supply voltages exceed their thresholds. DRIVE2 (Pin Connect this gate external MOSFET. This provides drive regulator's pass transistor. VSEN2 (Pin Connect this output linear regulator. voltage this regulated level predetermined logic-level status SELECT pin. This also monitored under-voltage events. SELECT (Pin This determines output voltage linear regulator. input sets output voltage 1.5V, while high input sets output voltage 3.3V. Soft-Start function initiates soft-start sequence. Initially, voltage rapidly increases approximately (this minimizes soft-start interval). Then internal 28µA current source charges external capacitor (CSS) 4.5V. error amplifier reference input terminal) output (COMP pin) clamped level proportional voltage. voltage slews from output clamp allows generation PHASE pulses increasing width that charge output capacitor(s). After output voltage increases approximately value, reference input clamp slows output voltage rate-of-rise provides smooth transition final voltage. Additionally, linear regulators' reference inputs clamped voltage proportional voltage. This method provides rapid controlled output voltage rise. Figure shows soft-start sequence typical application. voltage rapidly increases approximately error amplifier output voltage reach valley oscillator's triangle wave. oscillator's triangular wave form compared clamped error amplifier output voltage. voltage increases, pulse-width PHASE increases. interval increasing pulse-width continues until each output reaches sufficient voltage transfer control input reference clamp. consider 2.5V core output (VOUT1) Figure this time occurs During interval between error amplifier reference ramps final value converter regulates output voltage proportional voltage. input clamp voltage exceeds reference voltage output voltage regulation. remaining outputs also programmed follow voltage. PGOOD signal toggles `high' when output voltage levels have exceeded their under-voltage levels. Soft-Start Interval section under DRIVE3 (Pin Connect this gate external MOSFET. This provides drive 1.5V regulator's pass transistor. VSEN3 (Pin Connect this output 1.5V linear regulator. This monitored under-voltage events. DRIVE4 (Pin Connect this gate external MOSFET. This provides drive 1.8V regulator's pass transistor. VSEN4 (Pin Connect this output linear 1.8V regulator. This monitored undervoltage events. Description Operation HIP6021 monitors precisely controls output voltage levels (Refer Block Simplified Power System Diagrams, Typical Application Schematic). designed microprocessor computer applications with 3.3V, bias input from power supply. synchronous controller three linear controllers. controller (PWM) designed regulate microprocessor core voltage (VOUT1). controller drives MOSFETs synchronous-rectified buck converter configuration regulates microprocessor core voltage level programmed 5-bit digital-to-analog converter (DAC). linear controllers designed regulate advanced graphics port (AGP) voltage (VOUT2) digitally-programmable level 1.5V 3.3V. Selection 2-302 HIP6021 fully charged signal). under-voltage either linear output (VSEN2, VSEN3, VSEN4) ignored until after soft-start interval Figure This allows VOUT2 VOUT3 VOUT4 increase without fault startup. Cycling bias input voltage (+12VIN then resets counter fault latch. PGOOD SOFT-START (1V/DIV) Over-Voltage Protection VOUT2 3.3V) VOUT1 (DAC 2.5V) VOUT4 1.8V) OUTPUT VOLTAGES (0.5V/DIV) During operation, short upper MOSFET regulator (Q1) causes VOUT1 increase. When output exceeds over-voltage threshold 115% DACOUT, over-voltage comparator trips fault latch turns This blows input fuse reduces VOUT1. fault latch raises FAULT/RT VCC. separate over-voltage circuit provides protection during initial application power. voltages below power-on reset (and above ~4V), output level monitored voltages above 1.3V. Should VSEN1 exceed this level, lower MOSFET, driven VOUT3 1.5V) Over-Current Protection TIME FIGURE SOFT-START INTERVAL Applications Guidelines procedure determine soft-start interval. outputs protected against excessive over-currents. controller uses upper MOSFET's on-resistance, rDS(ON) monitor current protection against shorted output. linear controllers monitor their respective VSEN pins under-voltage events protect against excessive currents. Figure illustrates over-current protection with overload OUT1. overload applied current increases through inductor (LOUT1). time OVER-CURRENT comparator trips when voltage across rDS(ON)) exceeds level programmed ROCSET. This inhibits outputs, discharges soft-start capacitor (CSS) with 10mA current sink, increments counter. recharges initiates soft-start cycle with error amplifiers clamped soft-start. With OUT1 still overloaded, inductor current increases trip over-current comparator. Again, this inhibits outputs, soft-start voltage continues increasing before discharging. counter increments soft-start cycle repeats trips over-current comparator. voltage increases counter increments This sets fault latch disable converter. fault reported FAULT/RT pin. linear controllers operate same response over-current faults. differentiating factor linear controllers that they monitor VSEN pins under-voltage events. Should excessive currents cause voltage VSEN pins fall below linear undervoltage threshold, signal sets over-current latch fully charged. Blanking signal during charge interval allows linear outputs build above under-voltage threshold during normal operation. Cycling bias input power then resets counter fault latch. Fault Protection four outputs monitored protected against extreme overload. sustained overload output overvoltage VOUT1 output (VSEN1) disables outputs drives FAULT/RT VCC. OVERCURRENT LATCH 0.15V INHIBIT COUNTER FAULT LATCH FAULT FIGURE FAULT LOGIC SIMPLIFIED SCHEMATIC Figure shows simplified schematic fault logic. over-voltage detected VSEN1 immediately sets fault latch. sequence three over-current fault signals also sets fault latch. over-current latch dependent upon states over-current (OC), linear undervoltage (LUV) soft-start signals. window comparator monitors indicates when 2-303 HIP6021 FAULT/RT FAULT REPORTED COUNT trip point varies with MOSFET's rDS(ON) temperature variations. avoid over-current tripping normal operating load range, determine ROCSET resistor from equation above with: COUNT COUNT maximum rDS(ON) highest junction temperature. minimum IOCSET from specification table. Determine IPEAK IPEAK IOUT(MAX) (I)/2, where output inductor ripple current. SOFT-START OVERLOAD APPLIED equation ripple current section under component guidelines titled `Output Inductor Selection'. INDUCTOR CURRENT OUT1 Voltage Program output voltage converter programmed discrete levels between 1.3VDC 3.5VDC This output (OUT1) designed supply core voltage Intel's advanced microprocessors. voltage identification (VID) pins program internal voltage reference (DACOUT) with TTL-compatible 5-bit digital-to-analog converter. level DACOUT also sets PGOOD thresholds. Table specifies DACOUT voltage different combinations connections pins. pins left open logic input, because they internally pulled internal voltage about 10µA current source. Changing inputs during operation recommended could toggle PGOOD signal exercise over-voltage protection. `11111' combination disables opens PGOOD pin. TABLE OUT1 VOLTAGE PROGRAM NAME VID4 OVER-CURRENT TRIP: TIME FIGURE OVER-CURRENT OPERATION resistor (ROCSET) programs over-current trip level converter. shown Figure internal 200µA current sink, IOCSET develops voltage across ROCSET (VSET) that referenced DRIVE signal enables over-current comparator (OVERCURRENT). When voltage across upper MOSFET (VDS) exceeds VSET, over-current comparator trips over-current latch. Both VSET referenced small capacitor across ROCSET helps VOCSET track variations MOSFET switching. over-current function will trip peak inductor current (IPEAK) determined OCSET OCSET PEAK VID3 VID2 VID1 VID0 NOMINAL DACOUT VOLTAGE 1.30 1.35 1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 2.05 OCSET OCSET OCSET IOCSET 200µA OVERCURRENT DRIVE UGATE PHASE ROCSET VSET GATE CONTROL PHASE OCSET FIGURE OVER-CURRENT DETECTION 2-304 HIP6021 TABLE OUT1 VOLTAGE PROGRAM (Continued) NAME VID4 VID3 VID2 VID1 VID0 NOMINAL DACOUT VOLTAGE DRIVE4 VSEN4 COUT4 COUT3 VOUT3 VAUX +3.3VIN DRIVE3 VSEN3 HIP6021 FIGURE ADJUSTING OUTPUT VOLTAGE OUTPUTS VOUT4 Application Guidelines Soft-Start Interval Initially, soft-start function clamps error amplifier's output converter. This generates PHASE pulses increasing width that charge output capacitor(s). After output voltage increases approximately value, reference input error amplifier clamped voltage proportional voltage. resulting output voltages start-up shown Figure soft-start function controls output voltage rate rise limit current surge start-up. soft-start interval surge current programmed soft-start capacitor, CSS. Programming faster soft-start interval increases peak surge current. peak surge current occurs during initial output voltage rise value. NOTE: connected GND, open connected through pull-up resistors OUT2 Voltage Selection regulator output voltage internally discrete levels, based status SELECT pin. SELECT internally pulled `high', such that left open, output voltage default 3.3V. other discrete setting available 1.5V, which obtained grounding SELECT using jumper another suitable method capable sinking tens microamperes. status SELECT cannot changed during operation without immediately causing fault condition. OUT3 OUT4 Voltage Adjustability voltage (1.5V, OUT3) chip and/or cache memory voltage (1.8V, OUT4) internally simple, low-cost implementation typical Intel motherboard architectures. However, different voltage settings desired these outputs, provides necessary adaptability. Left open (NC), this sets fixed output voltages described above. Grounding this allows both output voltages means external resistor dividers shown Figure Shutdown HIP6021 features dedicated shutdown (SD). TTL-compatible, logic high signal applied this shuts down (disables) four outputs discharges soft-start capacitor. Following shutdown, logic signal re-enables outputs through initiation soft-start cycle. Left open this will asses logic state, internal pull-down resistor, thus enabling normal operation outputs. output does switch until soft-start voltage (VSS) exceeds oscillator's valley voltage. references each linear's error amplifier clamped soft-start voltage. Holding (with open drain collector signal) turns four regulators. `11111' code also shuts down 2-305 HIP6021 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 into circuit, lead device over-voltage stress. Careful component layout printed circuit design minimizes voltage spikes converter. Consider, example, turnoff transition upper MOSFET. Prior turn-off, upper MOSFET carrying full load current. During turn-off, current stops flowing upper MOSFET picked lower MOSFET Schottky diode. inductance switched current path generates large voltage spike during switching interval. Careful component selection, tight layout critical components, short, wide circuit traces minimize magnitude voltage spikes. Application Note ANTBD evaluation board drawings component placement printed circuit board. There sets critical components DC-DC converter using HIP6020 controller. 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. power components controller should placed first. Locate input capacitors, especially highfrequency ceramic decoupling capacitors, close power switches. Locate output inductor output capacitors between MOSFETs load. Locate controller close MOSFETs. critical small signal components include bypass capacitor soft-start capacitor, Locate these components close their connecting pins control Minimize leakage current paths from node, since internal current source only 28µA. multi-layer printed circuit board recommended. Figure 8shows connections critical components converter. Note that capacitors COUT each represent numerous physical capacitors. Dedicate solid layer ground plane make critical component ground connections with vias this layer. Dedicate another solid layer power plane break this plane into smaller islands common voltage levels. power plane should support input power output power nodes. copper filled polygons bottom circuit layers PHASE nodes, unnecessarily oversize these particular islands. Since PHASE nodes subjected very high dV/dt voltages, stray capacitor formed between these islands surrounding circuitry will tend couple switching noise. remaining printed circuit layers small signal wiring. wiring traces from control MOSFET gate source should sized carry peak currents. Controller Feedback Compensation controller uses voltage-mode control output regulation. This section highlights design consideration voltage-mode controller. Apply methods considerations only controller. Figure highlights voltage-mode control loop synchronous-rectified buck converter. output voltage (VOUT) regulated Reference voltage level. reference voltage level output voltage (DACOUT). error amplifier (Error Amp) output (VE/A) compared with oscillator (OSC) triangular wave provide pulsewidth modulated (PWM) wave with amplitude PHASE node. wave smoothed output filter CO). modulator transfer function small-signal transfer function VOUT/VE/A This function dominated Gain, given VIN/VOSC shaped output filter, with double pole break frequency zero FESR Modulator Break Frequency Equations compensation network consists error amplifier (internal HIP6021) impedance networks goal compensation network provide closed loop transfer function with high crossing frequency (f0dB) adequate phase margin. Phase margin difference between closed loop phase f0dB degrees. equations below relate compensation network's poles, zeros gain components (R1, Figure these guidelines locating poles zeros compensation network: Pick Gain (R2/R1) desired converter bandwidth Place Zero Below Filter's Double Pole (~75% FLC) Place Zero Filter's Double Pole Place Pole Zero Place Pole Half Switching Frequency Check Gain against Error Amplifier's Open-Loop Gain Estimate Phase Margin Repeat Necessary 2-306 HIP6021 +5VIN Compensation Break Frequency Equations +12V CVCC OCSET1 DRIVE2 UGATE1 PHASE1 COCSET1 ROCSET1 LOUT1 +3.3VIN VOUT2 VOUT1 LOAD COUT2 LGATE1 HIP6021 COUT1 VOUT3 COUT3 +3.3VIN VOUT4 DRIVE3 DRIVE4 PGND COUT4 Figure shows asymptotic plot DC-DC converter's gain frequency. actual Modulator Gain high gain peak dependent quality factor output filter, which shown Figure Using above guidelines should yield Compensation Gain similar curve plotted. open loop error amplifier gain bounds compensation gain. Check compensation gain with capabilities error amplifier. Closed Loop Gain constructed log-log graph Figure adding Modulator Gain Compensation Gain dB). This equivalent multiplying modulator transfer function compensation transfer function plotting gain. compensation gain uses external impedance networks provide stable, high bandwidth (BW) overall loop. stable control loop gain crossing with -20dB/decade slope phase margin greater than degrees. Include worst case component variations when determining phase margin. OPEN LOOP ERROR GAIN LOAD LOAD ISLAND POWER PLANE LAYER ISLAND CIRCUIT PLANE LAYER CONNECTION GROUND PLANE FIGURE PRINTED CIRCUIT BOARD POWER PLANES ISLANDS COMP DRIVER DRIVER PHASE VOUT LOAD GAIN (dB) MODULATOR GAIN VOSC COMPENSATION GAIN (PARASITIC) VE/A ERROR REFERENCE FESR 100K CLOSED LOOP GAIN DETAILED COMPENSATION COMPONENTS VOUT FREQUENCY (Hz) FIGURE ASYMPTOTIC BODE PLOT CONVERTER GAIN Component Selection Guidelines Output Capacitor Selection COMP HIP6021 DACOUT FIGURE VOLTAGE-MODE BUCK CONVERTER COMPENSATION DESIGN output capacitors each output have unique requirements. general, output capacitors should selected meet dynamic regulation requirements. Additionally, converters require output capacitor filter current ripple. load transient microprocessor core requires high quality capacitors supply high slew rate (di/dt) current demands. 2-307 HIP6021 Output Capacitors Modern microprocessors produce transient load rates above 1A/ns. High frequency capacitors initially supply transient current slow load rate-of-change seen bulk capacitors. bulk filter capacitor values generally determined (effective series resistance) voltage rating requirements rather than actual capacitance requirements. High frequency decoupling capacitors should placed close power pins load physically possible. careful inductance circuit board wiring that could cancel usefulness these inductance components. Consult with manufacturer load specific decoupling requirements. only specialized low-ESR capacitors intended switching-regulator applications bulk capacitors. bulk capacitor's determines output ripple voltage initial voltage drop following high slew-rate transient's edge. aluminum electrolytic capacitor's value related case size with lower available larger case sizes. However, equivalent series inductance (ESL) these capacitors increases with case size reduce usefulness capacitor high slew-rate transient loading. Unfortunately, specified parameter. Work with your capacitor supplier measure capacitor's impedance with frequency select suitable component. most cases, multiple electrolytic capacitors small case size perform better than single large case capacitor. HIP6021 will provide either 100% duty cycle response load transient. response time time interval required slew inductor current from initial current value post-transient current level. During this interval difference between inductor current transient current level must supplied output capacitor(s). Minimizing response time minimize output capacitance required. response time transient different application load removal load. following equations give approximate response time interval application removal transient load: TRAN RISE TRAN FALL where: ITRAN transient load current step, tRISE response time application load, tFALL response time removal load. sure check both these equations minimum maximum output levels worst case response time. Input Capacitor Selection important parameters bulk input capacitors voltage rating current rating. reliable operation, select bulk input capacitors with voltage current ratings above maximum input voltage largest current required circuit. capacitor voltage rating should least 1.25 times greater than maximum input voltage voltage rating times conservative guideline. current rating requirement input capacitor buck regulator approximately summation load current. input bypass capacitors control voltage overshoot across MOSFETs. ceramic capacitance high frequency decoupling bulk capacitors supply current. Small ceramic capacitors placed very close upper MOSFET suppress voltage induced parasitic circuit impedances. through-hole design, several electrolytic capacitors (Panasonic series Nichicon series Sanyo MV-GX equivalent) needed. surface mount designs, solid tantalum capacitors used, caution must exercised with regard capacitor surge current rating. These capacitors must capable handling surge-current power-up. series available from AVX, 593D series from Sprague both surge current tested. Linear Output Capacitors output capacitors linear regulators provide dynamic load current. linear controllers dominant pole compensation integrated into error amplifier insensitive output capacitor selection. Output capacitors should selected transient load regulation. Output Inductor Selection converter requires output inductor. output inductor selected meet output voltage ripple requirements sets converter's response time load transient. inductor value determines converter's ripple current ripple voltage function ripple current. ripple voltage current approximated following equations: Increasing value inductance reduces ripple current voltage. However, large inductance values increase converter's response time load transient. parameters limiting converter's response load transient time required change inductor current. Given sufficiently fast control loop design, MOSFET Selection/Considerations HIP6021 requires external transistors. N-channel MOSFETs used synchronous-rectified buck topology PWM1 converter. recommended that linear regulator pass element N-channel MOSFET well. memory linear controllers also 2-308 HIP6021 each drive MOSFET bipolar pass transistor. these transistors should selected based upon rDS(ON) current gain, saturation voltages, gate supply requirements, thermal management considerations. LESS +12V MOSFET Selection Considerations high-current applications, MOSFET power dissipation, package selection heatsink dominant design factors. power dissipation includes loss components; conduction loss switching loss. These losses distributed between upper lower MOSFETs according duty factor (see equations below). conduction losses main component power dissipation lower MOSFETs. Only upper MOSFET significant switching losses, since lower device turns into near zero voltage. equations below assume linear voltage-current transitions model power loss reverserecovery lower MOSFET's body diode. gatecharge losses dissipated HIP6021 don't heat MOSFETs. However, large gate-charge increases switching time, which increases upper MOSFET switching losses. Ensure that both MOSFETs within their maximum junction temperature high ambient temperature calculating temperature rise according package thermal-resistance specifications. separate heatsink necessary depending upon MOSFET power, package type, ambient temperature flow. UPPER LOWER HIP6021 UGATE PHASE NOTE: NOTE: LGATE PGND FIGURE UPPER GATE DRIVE DIRECT DRIVE OPTION Linear Controller Transistor Selection main criteria selection transistors linear regulators package selection efficient removal heat. power dissipated linear regulator LINEAR Select package heatsink that maintains junction temperature below rating with maximum expected ambient temperature. When selecting bipolar transistors with linear controllers, insure current gain given operating sufficiently large provide desired output load current when base with minimum driver output current. rDS(ON) different equations above even same device used both. This because gate drive applied upper MOSFET different than lower MOSFET. Figure shows gate drive where upper MOSFET's gate-to-source voltage approximately less input supply. main power +12VDC bias, gate-to-source voltage lower gate drive voltage +12VDC. logic-level MOSFET good choice logic-level MOSFET used absolute gate-to-source voltage rating exceeds maximum voltage applied VCC. Rectifier clamp that catches negative inductor swing during dead time between turn lower MOSFET turn upper MOSFET. diode must Schottky type prevent lossy parasitic MOSFET body diode from conducting. acceptable omit diode body diode lower MOSFET clamp negative inductor swing, efficiency could drop percent result. diode's rated reverse breakdown voltage must greater than maximum input voltage. 2-309 HIP6021 HIP6021 DC-DC Converter Application Circuit Figure shows application circuit power supply microprocessor computer system. power supply provides microprocessor core voltage (VOUT1), voltage (VOUT2), voltage (VOUT3), memory voltage (VOUT4) from +3.3V, +5VDC, +12VDC. +12VIN +5VIN C1-6 6x1000µF 1000pF detailed information circuit, including Bill-ofMaterials circuit board description, Application Note AN9836. Also Intersil's page (http://www.intersil.com) Intersil AnswerFAX (407-724-7800) Document 99836 latest information. FAULT/RT +3.3VIN OCSET PGOOD 1.0K POWERGOOD VAUX DRIVE2 VOUT2 (3.3V 1.5V) VSEN2 HUF76121D3S UGATE PHASE Q1,2 2xHUF76143S3S 4.2µH VOUT1 (1.3V-3.5V) C10,11 2x1000µF LGATE C12-19 8x1000µF 10.2K PGND TYPEDET SELECT VSEN1 10pF 1.62k HIP6021 HUF76107D3S VOUT3 (1.5V) DRIVE3 VSEN3 C23,24 2x1000µF HUF76107D3S VOUT4 (1.8V) C25,26 2x1000µF DRIVE4 VSEN4 VID0 VID1 VID2 VID3 VID4 2.7nF 150K COMP 0.22µF 499K 0.1µF FIGURE POWER SUPPLY APPLICATION CIRCUIT MICROPROCESSOR COMPUTER SYSTEM Intersil semiconductor products manufactured, assembled tested under ISO9000 quality systems certification. Intersil semiconductor products sold description only. Intersil Corporation reserves right make changes circuit design and/or specifications time without notice. Accordingly, reader cautioned verify that data sheets current before placing orders. Information furnished Intersil believed accurate reliable. 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