5-BIT PROGRAMMABLE SYNCHRONOUS BUCK PLUS NON-SYNCHRONOUS, CONTROLLER 2
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IRU3007
5-BIT PROGRAMMABLE SYNCHRONOUS BUCK PLUS NON-SYNCHRONOUS, CONTROLLER 200mA ON-BOARD
Provides single chip solution Vcore, GTL+, clock supply 3.3V switcher on-board Second Switcher Provides Simple Control on-board 3.3V supply 200mA on-board regulator Designed meet Intel specification Pentium IIOn-board programs output voltage from 1.3V 3.5V Linear regulator controller board 1.5V GTL+ supply Loss-less short circuit protection Synchronous operation allows maximum efficiency Patented architecture allows fixed frequency operation well 100% duty cycle during dynamic load Minimum part count Soft start High current totem pole driver direct driving external Power MOSFET Power Good function monitors outputs circuitry protects switcher outputs generates fault output Thermal shutdown
DESCRIPTION
IRU3007 controller specifically designed meet Intel specification Pentium IImicroprocessor applications well next generation family processors. IRU3007 provides single chip controller Vcore, controller GTL+ internal 200mA regulator clock supply which required Pentium applications. also contains switching controller convert 3.3V regulator board applications that either uses type power supply desired rely power supply's 3.3V output. These devices feature patented topology that combination with external components shown typical application circuit, will provide excess output current onboard DC/DC converter while automatically providing right output voltage internal DAC. IRU3007 also features, loss-less current sensing both switchers using RDS(on) high-side power MOSFET sensing resistor, internal current limiting clock supply, Power Good window comparator that switches open collector output when outputs outside pre-programmed window. Other features device are: Undervoltage lockout both supplies, external programmable soft start function, programming oscillator frequency external resistor, circuitry both switcher outputs internal thermal shutdown.
APPLICATIONS
Total Power Solution Pentium processor application
TYPICAL APPLICATION
SWITCHER2 CONTROL SWITCHER1 CONTROL
Vout2
Vout1
IRU3007
Vout3
LINEAR CONTROL
LINEAR REGULATOR
3007app3-1.0
Vout4
Notes: Pentium Pentium trademarks Intel Corp.
PACKAGE ORDER INFORMATION
(°C)
Rev. 12/8/00
Device IRU3007CW
Package 28-pin Plastic SOIC
4-17
IRU3007
ABSOLUTE MAXIMUM RATINGS
supply Voltage Supply Voltage Storage Temperature Range Operating Junction Temperature Range 150° 125°
PACKAGE INFORMATION
WIDE BODY PLASTIC SOIC
VIEW
UGate2 Phase2 VID4 VID3 VID2 VID1 VID0 PGood OCSet2 Fault
UGate1 Phase1 LGate1 PGnd OCSet1 Vsen1 Gate3 Vout4 Vsen2
=80°C/W
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over, 12V, Ta=0 Typical values refer =25° duty cycle pulse testing used which keeps junction case temperatures equal ambient temperature. PARAMETER TEST CONDITION UNITS Supply UVLO Section UVLO Threshold-12V Supply ramping UVLO Hysterises-12V UVLO Threshold-5V Supply ramping UVLO Hysterises-5V Supply Current Operating Supply Current Switching Controllers; Vcore (Vout (Vout Section (Vcore only) output voltage (note Output Line Regulation Output Temp Variation Input Input input internal pull-up resistor Vfb2 Voltage
0.99Vs
1.01Vs
Rev. 12/8/00
4-18
IRU3007
PARAMETER Error Comparator Section Input bias current Input Offset Voltage Delay Output Current Limit Section Threshold Current Comp Offset Voltage Hiccup Duty Cycle Output Drivers Section Rise Time Fall Time Dead band Time Between High side Synch Drive (Vcore Switcher Only) Oscillator Section (internal) Frequency 2.5V Regulator (Vout Reference Voltage Reference Voltage Dropout Voltage Load Regulation Line Regulation Input bias current Output Current Current limit Thermal Shutdown 1.5V Regulator (Vout Reference Voltage Reference Voltage Input bias current Output Drive Current Power Good Section Core lower trip point Core upper trip point Core Hysterises Core upper trip point Core lower trip point Core Hysterises lower trip point upper trip point lower trip point upper trip point lower trip point upper trip point Power Good Output Power Good Output Fault (Overvoltage) Section Core O.V. upper trip point Core O.V. lower trip point Soft Start Section Pull resistor TEST CONDITION Css=0.1µF CL=3000pF CL=3000pF UNITS
Vdiff=10mV
CL=3000pF Rt=Open Ta=25, Vout4 200mA 1mA< <200mA 3.1V<VIO<4V, Vo=2.5V
1.260 1.260
Ta=25, GATE3 1.260 1.260 Vsen1 ramping down Vsen1 ramping Vsen1 ramping Vsen1 ramping down Vsen2 ramping down Vsen2 ramping ramping down ramping ramping down ramping RL=3mA RL=5K pull Vsen1 ramping Vsen1 ramping down OCset=0V, Phase=5V 0.90Vs 0.92Vs .02Vs 1.10Vs 1.08Vs .02Vs 0.95 1.05 0.95 1.05 1.17Vs 1.15Vs
Rev. 12/8/00
4-19
IRU3007
PARAMETER O.V. upper trip point O.V. lower trip point FAULT Output TEST CONDITION Vsen2 ramping Vsen2 ramping down Io=3mA UNITS
Note refers point voltage given Table 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
Table point voltage codes
DESCRIPTIONS
PIN# SYMBOL VID0 Description input that programs output voltage. This compatible that realizes logic either Open. When left open, this pulled internally resistor supply. Input that programs output voltage. This compatible that realizes logic either Open. When left open, this pulled internally resistor supply. Input that programs output voltage. This compatible that realizes logic either Open. When left open, this pulled internally resistor supply. input that programs output voltage. This compatible that realizes logic either Open. When left open, this pulled internally resistor supply. This selects range output voltages DAC.When state range 1.3V 2.05V when switches state range 2.0V 3.5V. This compatible that realizes logic either Open. When left open, this pulled internally resistor supply. This open collector output that switches when outputs outside specified under voltage trip point. also switches when Vsen1 more than above voltage setting. This provides feedback synchronous switching regulator. Typically this connected directly output switching regulator. However, resistor divider recommended connected from this Vout1 adjust output voltage drop output voltage that caused trace resistance. value resistor connected from Vout1 must less than 100.
VID1
VID2
VID3
VID4
PGOOD
4-20
Rev. 12/8/00
IRU3007
PIN# SYMBOL VSEN1 DESCRIPTION This internally connected undervoltage overvoltage comparators sensing Vcore status. must connected directly Vcore supply. This provides feedback non-synchronous switching regulator. resistor divider connected from this Vout2 that sets output voltage. value resistor connected from Vout2 must less than 100. This connected output switching regulator. input that provides sensing Under/Over voltage circuitry supply well power internal regulator. This connected Drain power MOSFET Core supply provides positive sensing internal current sensing circuitry. external resistor programs current sense threshold depending power MOSFET. external capacitor placed parallel with programming resistor provide high frequency noise filtering. This connected Source power MOSFET Core supply provides negative sensing internal current sensing circuitry. This connected Drain power MOSFET supply provides positive sensing internal current sensing circuitry. external resistor programs current sense threshold depending power MOSFET. external capacitor placed parallel with programming resistor provide high frequency noise filtering. This connected Source power MOSFET supply provides negative sensing internal current sensing circuitry. This provides soft start switching regulators. internal resistor charges external capacitor that connected from supply this which ramps outputs switching regulators, preventing outputs from overshooting well limiting input current. second function Soft Start provide long time (HICCUP) synchronous MOSFET during current limiting. This dual function. acts output circuitry used program frequency using external resistor. When used fault detector, switcher outputs exceed over voltage protection trip point, FAULT switches soft start discharged. FAULT connected external circuitry, needs buffered shown application circuit. This controls gate external transistor 1.5V GTL+ linear regulator This provides feedback linear regulator that output drive GATE3 This output internal regulator This provides feedback internal regulator that output Vout4 This serves ground must connected directly ground plane This serves Power ground must connected directly plane close source synchronous MOSFET. high frequency capacitor (typically 1µF) must connected from this noise free operation. Output driver synchronous power MOSFET Core supply Output driver high-side power MOSFET Core supply Output driver high-side power MOSFET supply This connected supply serves power output drivers. high frequency capacitor (typically 1µF) must placed close this PGND connected directly from this plane noise free operation. supply voltage. high frequency capacitor (0.1 1µF) must placed close this connected from this plane noise free operation. connect
VSEN2
OCSet1
PHASE1
OCSet2
PHASE2
FAULT/Rt
GATE3 VOUT4 PGND LGATE1 UGATE1 UGATE2
Rev. 12/8/00
4-21
IRU3007
BLOCK DIAGRAM
4.3V Enable Over Voltage Vset Enable
UGate1
UVLO
Vset
1.17Vset
VID0 VID1 VID2 VID3 VID4 Vsen1 Gate3 Vsen2
Control
2.5V
Slope Comp
LGate1 Phase1 OCSet1 Phase2 OCSet2
5Bit
1.1Vset Enable
Soft Start Fault Logic
Over Current
200uA
Fault
0.9Vset
Slope Comp
1.26V 0.9V
UGate2 PGnd
2.0V Enable
Control
Vout4 PGood
3007blk1-1.4
Figure Simplified block diagram IRU3007
4-22
Rev. 12/8/00
IRU3007
TYPICAL APPLICATION
OCSet2 UGate2 OCSet1 UGate1
Vout2 3.0V 3.5V
Phase2
Phase1 LGate1 PGnd
Vout1 1.8V 3.5V
Vsen2
Vsen1
PGood Vout3 1.5V Vout4 2.5V
3007app1-1.2
PGood
Gate3
Fault/Rt
Vout4
Figure Typical application IRU3007 board DC-DC converter providing power Vcore, GTL+, Clock supply well board 3.3V supply Deschutes next generation processor applications
Rev. 12/8/00
4-23
IRU3007
IRU3007 Application Parts List Desig Description MOSFET R1,5,13, Resistor Resistor Resistor Resistor Resistor Resistor Resistor 0603 100, 0603 19.1, 0603 1.5k, 0603 1206 3.3k, 0603 2.2k, 0603 220k, 0603 0603 Resistor MOSFET MOSFET MOSFET with Schottky Diode Inductor Inductor Inductor Capacitor, Electrolytic Capacitor, Electrolytic Capacitor, Electrolytic Capacitor, Ceramic Capacitor, Ceramic Capacitor, Ceramic Capacitor, Electrolytic Capacitor, Electrolytic Capacitor, Electrolytic Capacitor, Electrolytic Resistor Part IRL3103S, TO-263 package IRLR024, TO-252 package IRL3103S, TO-263 package IRL3103D1S, TO-263 package MBRB1035, TO-263 package L=1µH, 5052 core with turns 1.0mm wire L=4.7µH, 5052 core with turns 1.0mm wire L=2.7µH, 5052B core with turns 1.2mm wire 6MV1500GX, 1500µF, 6.3V 10MV470GX, 470µF,10V 10MV1200GX, 1200µF,10V 1000pF, 0603 220pF, 0603 1µF, 0805 1µF, 0603 10MV1200GX, 1200µF,10V 6MV1500GX, 1500µF,6.3V 6MV1000GX, 1000µF,6.3V 6MV150GX, 150µF,6.3V 4.7, 1206 Sanyo Sanyo Sanyo Sanyo Sanyo Sanyo Sanyo Micro Metal Micro Metal Manuf Micro Metal
Capacitor, Ceramic
R16, Resistor
4-24
Rev. 12/8/00
IRU3007
TYPICAL APPLICATION
(Dual Layout with HIP6019)
Vout2 3.0V 3.5V PGnd Vsen2 V5/Comp2 Gate3 Vout3 1.5V VID0 VID1 VID2 VID3 Vout4 2.5V
3007app2-1.5
OCSet1 UGate1
OCSet2 UGate2
Phase2
Phase1 LGate1
Vout1 1.8V 3.5V
Vsen1
NC/Comp1
PGood Fault/Rt
PGood
Vout4
VID4
Figure Typical application IRU3007 dual layout with HIP6019 board DC-DC converter providing power Vcore, GTL+, Clock supply well board 3.3V supply Deschutes next generation processor application Components that need modified make dual layout work IRU3007 HIP6019
Part HIP6019 IRU3007
Short
Open
Harris parts list value
Table Dual layout component table
Rev. 12/8/00
4-25
IRU3007
IRU3007 Application Parts List Dual Layout with HIP6019 Desig Description MOSFET C9,15,19 R1,13,14 R3,6,7,8 Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor 0603 100, 0603 Table dual layout component 0603 19.1, 0603 1.5k, 0603 1206 0603 3.3k, 0603 2.2k, 0603 220k, 0603 0603 Capaci Ceram Capacitor, Ceramic Capacitor, Electrolytic Capacitor, Electrolytic Capacitor, Electrolytic Capacitor, Electrolytic Resistor MOSFET MOSFET MOSFET with Schottky Diode Inductor Inductor Inductor Capacitor, Electrolytic Capacitor, Electrolytic Capacitor, Electrolytic Capacitor, Ceramic Capacitor, Ceramic Part IRL3103S, TO-263 package IRLR024, TO-252 package IRL3103S, TO-263 package IRL3103D1S, TO-263 package MBRB1035, TO-263 package L=1µH, 5052 core with turns wire L=4.7µH, 5052 core with turns 1.0mm wire L=2.7µH, 5052B core with turns 1.2mm wire 6MV1500GX, 1500µF,6.3V 10MV470GX, 470µF,10V 10MV1200GX, 1200µF,10V 1000pF, 0603 220pF, 0603 Table dual layout component 0603 1µF, 0805 1µF, 0603 10MV1200GX, 1200µF, 6MV1500GX, 1500µF, 6.3V 6MV1000GX, 1000µF, 6.3V 6MV150GX, 150µF, 6.3V 4.7, 1206 Sanyo Sanyo Sanyo Sanyo Sanyo Sanyo Sanyo Micro Metal Micro Metal Manuf Micro Metal
C6,7,11,12 Capaci Ceram
R16,17,21 Resistor
4-26
Rev. 12/8/00
IRU3007
Application Information
example calculate components application circuit given below. Assuming, output conditions that this regulator must meet Vcore: Vo=2.8V Io=14.2A, Vo=185mV, Io=14.2A Vo=2V Io=14.2A, Vo=140mV, Io=14.2A Also, on-board 3.3V supply must able provide load current maintain less than total output voltage variation. regulator design will done such that meets worst case requirement each condition. Output Capacitor Selection Vcore first step select output capacitor. This done primarily selecting maximum value that meets transient voltage budget total specification. Assuming that regulators initial accuracy plus output ripple output voltage, then maximum output capacitor calculated 14.2 when transitioning from light load full load vice versa. accomplish this, output regulator typically about half drop that results from light load full load. example, total resistance from output capacitors Slot back 3007 total change from light load full load 14A, then output voltage measured resistor divider which also connected output capacitors this case, must half 70mV 35mV higher than voltage setting. This intentional voltage level shifting during load transient eases requirement output capacitor cost load regulation. show that requirement eases half total trace resistance. example, requirement output capacitors without voltage level shifting must then after level shifting will only need 8.5m trace resistance (7+5/2=9.5). However, must careful that combined "voltage level shifting" transient response still within maximum tolerance Intel specification. insure this, maximum trace resistance must less than: 2(Vspec 0.02*Vo Vo)/I Where Rs=Total maximum trace resistance allowed Vspec=Intel total voltage spec Vo=Output voltage Vo=Output ripple voltage I=load current step example, assuming: Vspec=±140 mV=±0.1V output Vo=2V Vo=assume 10mV=0.01V I=14.2A Then calculated 2(0.140 0.02*2 0.01)/14.2=12.6m However, resistor this value used, maximum power dissipated trace external resistor being used) must also considered. example Rs=12.6 power dissipated (Io^2)*Rs=(14.2^2)*12.6=2.54W. This power dissipated system. Rs=5m, then power dissipated about which much more acceptable. level shifting implemented, then maximum output capacitor shown previously
Sanyo MVGX series good choice achieve both price performance goals. 6MV1500GX, 1500µF, 6.3V less than typical. Selecting these capacitors parallel which achieves goal. Other type Electrolytic capacitors from other manufacturers consider Panasonic series Nichicon series. 3.3V supply 3.3V supply, since there fast transient requirement, 1500µF capacitors sufficient. Reducing Output Capacitors Using Voltage Level Shifting Technique trace resistance external resistor from output switching regulator Slot used circuit advantage possibly reduce number output capacitors, level shifting regulation point
Rev. 12/8/00
4-27
IRU3007
which translated 1500µF, 6MV1500GX type Sanyo capacitors. With Rs=5m, maximum becomes 9.5m which equivalent caps. Another important consideration that trace being used implement resistor, power dissipated trace increases case temperature output capacitors which could seriously effect life time output capacitors. Output Inductor Selection output inductance must selected such that under line maximum output voltage condition, inductor current slope times output capacitor ramping faster than capacitor voltage drooping during load current step. However, inductor small, output ripple current ripple voltage become large. solution bring ripple current down increase switching frequency, however that will cost reduced efficiency higher system cost. following formulas derived achieve optimum performance without many design iterations. maximum output inductance calculated using following equation: Vinmin Vomax Where Vinmin Minimum input voltage 14.2 =0.006 9000 4.75 2.8) 14.2) 3.7µH Assuming that programmed switching frequency 200KHZ, inductor designed using Micrometals' powder iron core material. summary design outlined below: selected core material Powder Iron, selected core T50-52D from Micro Metal wound with turns wire, resulting inductance with resistance. Assuming switching frequency; 200KHZ, inductor ripple current output ripple voltage calculated using following equations: 1/Fsw Switching Period Vsync Vsync Duty Cycle High-side MOSFET Voltage MOSFET On-Resistance Toff Vsync Synchronous MOSFET Voltage=Io Vsync Toff Inductor Ripple Current Output Ripple Voltage example 2.8V 14.2 load, assuming IRL3103 MOSFET both switches with maximum resistance 19m, have: 200000 5µSec =Vsync= 14.2*0.019=0.27 0.27 0.27 0.27 0.61 0.61 3.1µSec Toff 1.9µSec 0.27 1.94 1.94 .006 .011 Power Component Selection Vcore Assuming IRL3103 MOSFETs power components, will calculate maximum power dissipation follows: high side switch maximum power dissipation happens maximum maximum duty cycle. Dmax 0.27 4.75 0.27 0.27 0.65 Dmax Io^2*RDS(max) Pdh= 0.65*14.2^2*0.029=3.8 RDS(max)=Maximum RDS(on) MOSFET 125°C synch MOSFET, maximum power dissipation happens minimum minimum duty cycle. Dmin 0.27 5.25 0.27 0.27 0.43 (1-Dmin)*Io^2*Rds(max) Pds=(1 0.43) 14.2^2 0.029 3.33 3.3V Supply Again, high side switch maximum power dissipation happens maximum maximum duty cycle. duty cycle equation synchronous replaces forward voltage diode with Synch MOSFET voltage. equation below, Vf=0.5V Dmax 4.75 0.27 0.76
4-28
Rev. 12/8/00
IRU3007
Dmax Io^2*RDS(max) Pdh= 0.76*10^2*0.029=2.21 RDS(max)=Maximum RDS(on) MOSFET 125°C diode, maximum power dissipation happens minimum minimum duty cycle. Dmin 5.25 0.27 0.69 (1-Dmin)*Io*Vf=(1 0.69) 1.55 Switcher Current Limit Protection IRU3007 uses MOSFET RDS(on) sensing resistor sense MOSFET current compares programmed voltage which externally resistor (Rcs) placed between drain MOSFET OCSet1 terminal shown application circuit. example, desired current limit point synchronous synchronous, from previous selection, maximum MOSFET RDS(on) =19mW, then current sense resistor calculated Vcore Vcs=IcL*Rds=22*0.019=0.418V Where: Ib=200µA internal current setting IRU3007 3.3V supply Vcs=IcL*Rds=16*0.019=0.3V Rcs=Vcs/Ib=(0.3V)/(200µA)=1.50k 1.5V, GTL+ Supply Power MOSFET Selection first step selecting power MOSFET 1.5V linear regulator select maximum RDS(on) pass transistor based input output Dropout voltage maximum load current. RDS(max) (Vin Vo)/IL Vo=1.5V, 3.3V IL=2A RDS(max)=(3.3 1.5)/2= Note that since MOSFETs RDS(on) increases with temperature, this number must divided 1.5, order find RDS(on) room temperature. Motorola MTP3055VL maximum 0.18 RDS(on) room temperature, which meets requirement. select heatsink MOSFET first step calculate maximum power dissipation device then follow same procedure switcher. Where Power Dissipation Linear Regulator Linear Regulator Load Current 1.5V load: (3.3 1.5)*2=3.6 Assumi max=125°C (1.8 0.05) With maximum heat sink temperature calculated previous step, heat-sink-to-air thermal resistance (sa) calculated follows: Assuming Ta=35 Temperature Rise Above Ambient T/Pd °C/W same heat sink selected switcher MOSFETs also suitable 1.5V regulator. 2.5V, Clock Supply IRU3007 provides complete 2.5V regulator with minimum 200mA current capability. internal regulator short circuit protection with internal thermal shutdown. 1.5V 2.5V Supply Resistor Divider Selection Since internal voltage reference linear regulators 1.26V IRU3007, there need external resistor dividers step voltage. resistor dividers selected using following equations: Vo=(1+Rt/Rb)*Vref Where: Rt=Top resistor divider Rb=Bottom resistor divider Vref=1.26V typical 1.5V supply: Assuming Rb=1k Rt=Rb*[(Vo/Vref) Rt=1*[(1.5/1.26) 1]=191
Rev. 12/8/00
4-29
IRU3007
2.5V supply: Assuming Rb=1.02k Rt=Rb*[(Vo/Vref) Rt=1.02*[(2.5/1.26) 1]=1k Switcher Output Voltage Adjust Vcore discussed earlier, trace resistance from output switching regulator Slot used circuit advantage possibly reduce number output capacitors, level shifting regulation point when transitioning from light load full load vice versa. account drop, output regulator typically about half drop that results from light load full load. example, total resistance from output capacitors Slot back IRU3007 total change from light load full load 14A, then output voltage measured resistor divider which also connected output capacitors this case, must half 70mV 35mV higher than voltage setting. this, resistor resistor divider (R12 application circuit) 100, calculated. example, voltage setting 2.8V desired output under light load 2.835V, then calculated using following formula: R19= 100*{Vdac /(Vo 1.004*Vdac)} R19= 100*{2.8 /(2.835 1.004*2.800)} 11.76 Select 11.8 Note: value resistor must exceed 100. bottom resistor then adjusted raise output voltage. 3.3V supply loop gain non-synchronous switching regulator intentionally take advantage level shifting technique reduce number output capacitors. Typically there drop output voltage from light load (discontinuous conduction mode) full load (continuous conduction mode) 3.3V supply. account this, output voltage 3.5V typically. same procedure synchronous applied non-synch with exception that internal voltage reference this regulator internally following equations output voltage setting non-synchronous assuming Vo=3.5V resistor, application circuit) R2=75. bottom resistor, calculated follows: R2*{2 /(Vo 75*{2 /(3.5 100, Note: value resistor, must exceed 100. Soft Start Capacitor Selection soft start capacitor must selected such that during start when output capacitors charging peak inductor current does reach current limit threshhold. minimum capacitor insures this most applications. internal 10µA current source charges soft start capacitor which slowly ramps inverting input comparator Vfb3. This insures output voltage ramp same rate soft start thereby limiting input current. example, with 10µA internal current source ramp rate t)=I/C 1V/100mS. Assuming that output capacitance 9000µF, maximum start current will I=9000µF*(1V/100mS)=0.09A Input Filter highly recommended place inductor between system supply input capacitors switching regulator isolate supply from switching noise that occurs during turn switching components. Typically inductor range will sufficient this type application. External Shutdown best shutdown IRU3007 pull down soft start using external small signal transistor such 2N3904 2N7002 small signal MOSFET. This allows slow ramp output, same power Layout Considerations Switching regulators require careful attention layout components, specifically power components since they switch large currents. These switching components create large amount voltage spikes
4-30
Rev. 12/8/00
IRU3007
high frequency harmonics some critical components away from each other connected with inductive traces. following guideline place critical components connections between them order minimize above issues. Start layout first placing power components: Place close Place input capacitors high side MOSFETs, close their respective input caps possible. Place synchronous MOSFET, close each other possible with intention that source drain shortest length. Repeat this synchronous. Place snubber between Repeat this with respect synchronous. Place output inductor output capacitors, between MOSFET load with output capacitors distributed along slot close Repeat this with respect non-synchronous. Place bypass capacitors, right next pins. next 12V, next Place IRU3007 such that output drives, pins relatively short distance from gates non-synch MOSFET must also situated such that distance from gate IRU3007 also relatively short. Place resistor dividers close their respective feedback pins. Place 2.5V output capacitor, close 1.5V output capacitor, close MOSFET. Note: better place 1.5V linear regulator components close IRU3007 then trace from output regulator load. However, this possible then trace from linear drive output pin, must away from high frequency data signals. Component connections: Note: extremely important that data should passing through switching regulator section specifically close fast transition nodes such drives inductor voltage. Using layer board, dedicate layer GND, another layer power layer 3.3V, Vcore, 1.5V possible 2.5V. Connect grounds ground plane using direct vias ground plane. large inductance/low impedance plane connect following connections either using component side solder side. Drain drain Source Drain Source cathode drain cathode output capacitors, output capacitors, load, slot Input filter drain source minimum inch width trace from capacitor Connect rest components using shortest connection possible. critical, place high frequency ceramic capacitors close clock chip termination resistors provide local bypassing. Place close close
Rev. 12/8/00
4-31
IRU3007
Notes
4-32
Rev. 12/8/00
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