5-BIT PROGRAMMABLE SYNCHRONOUS BUCK CONTROLLER Dual layout compat

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5-BIT PROGRAMMABLE SYNCHRONOUS BUCK CONTROLLER Dual layout compat

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IRU3011
5-BIT PROGRAMMABLE SYNCHRONOUS BUCK CONTROLLER
Dual layout compatible with HIP6004A Designed meet Intel specification VRM8.4 Pentium IIIOn board programs output voltage from 1.3V 3.5V. IRU3011 remains code (11111). Loss-less short circuit protection Synchronous operation allows maximum efficiency Patented architecture allows fixed frequency operation well 100% duty cycle during dynamic load Over voltage protection output Soft start High current totem pole driver direct driving external power MOSFET Power Good function
DESCRIPTION
IRU3011 controller specifically designed meet Intel specification latest Pentium IIImicroprocessor applications well next generation family processors. These products feature patented topology that combination with external components shown typical application circuit, will provide excess output current on-board DC/DC converter while automatically providing right output voltage 5-bit internal DAC. These devices also features, loss-less current sensing using RDS(on) high side Power MOSFET sensing resistor, Power Good window comparator that switches open collector output when output outside ±10% window Over Voltage Protection output. Other features device are: Undervoltage lockout both supplies, external programmable soft start function well programming oscillator frequency using external capacitor.
APPLICATIONS
Pentium Pentium IIprocessor converter application cost Pentium with
TYPICAL APPLICATION
Vout (1.3V 3.5V)
NC/Gnd HDrv Boot CS17 LDrv NC/Sen V5/Comp Ct/Rt Power Good
3011app1-1.1
US3011 IRU3011
VID4 VID3 VID2 VID1 VID0
Note: Pentium Pentium trade marks Intel Corp
PACKAGE ORDER INFORMATION
(°C) Device IRU3011CW Package 20-pin Plastic SOIC Voltage Range 1.3V 3.5V
Rev. 12/8/00
4-33
IRU3011
ABSOLUTE MAXIMUM RATINGS
supply Voltage Supply Voltage Storage Temperature Range Operating Junction Temperature Range 150° 125°
PACKAGE INFORMATION
WIDE BODY PLASTIC SOIC
VIEW
LDrv HDrv CS12
=85°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 Section output voltage (note Output Line Regulation Output Temp Variation Input Input input internal pull-up resistor Power Good Section Under voltage lower trip point Under voltage upper trip point Hysterises Over voltage upper trip point Over voltage lower trip point Hysterises Power Good Output Power Good Output Soft Start Section Soft Start Current TEST CONDITION 0.99Vs 1.01Vs UNITS
Vout ramping down Vout ramping Vout ramping Vout ramping down pull
0.89Vs .015Vs 1.09Vs .015Vs
0.90Vs 0.92Vs .02Vs 1.10Vs 1.08Vs .02Vs
0.91Vs .025Vs 1.11Vs .025Vs
Rev. 12/8/00
4-34
IRU3011
PARAMETER UVLO Section UVLO Threshold-12V UVLO Hysterises-12V UVLO Threshold-5V UVLO Hysterises-5V Error Comparator Section Input bias current Input Offset Voltage Delay Output Current Limit Section C.S. Threshold Current C.S. Comp Offset Voltage Hiccup Duty Cycle Supply Current Operating Supply Current TEST CONDITION Supply ramping Supply ramping 10.8 UNITS
Vdiff=10mV Css=0.1µF CL=3000pF CL=3000pF CL=3000pF CL=3000pF Ct=150pF
Output Drivers Section Rise Time Fall Time Dead band Time Oscillator Section Frequency Valley Peak Over Voltage Section Drive Current
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
Rev. 12/8/00
4-35
IRU3011
DESCRIPTIONS
PIN# SYMBOL DESCRIPTION input that programs output voltage. This pulled externally resistor either 3.3V supply. Input that programs output voltage. This pulled externally resistor either 3.3V supply. Input that programs output voltage. This pulled externally resistor either 3.3V supply. input that programs output voltage. This pulled externally resistor either 3.3V supply. This selects range output voltages DAC. This open collector output that switches when output converter within ±10% (typ) nominal output voltage. When PWRGD switches saturation voltage less than 0.4V 3mA. This connected directly output Core supply provide feedback Error comparator. 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 provides soft start switching regulator. internal current source charges external capacitor that connected from this which ramps outputs switching regulator, preventing outputs from overshooting well limiting input current. second function Soft Start provide long time synchronous MOSFET Catch diode (HICCUP) during current limiting. This programs oscillator frequency range 50kHZ 500kHZ with external capacitor connected from this GND. This serves ground must connected directly ground plane. high frequency capacitor (0.1 1µF) must connected from pins this noise free operation. Output driver synchronous power MOSFET Output driver high side power MOSFET This connected supply serves power output drivers. high frequency capacitor (0.1 1µF) must connected directly from this order supply peak current power MOSFET during transitions. supply voltage Over voltage comparator output connect
CSSS
LDrv HDrv
15,11
4-36
Rev. 12/8/00
IRU3011
BLOCK DIAGRAM
Enable Vset Enable
UVLO
Vset
HDrv Control
5Bit DAC, Ctrl Logic
Enable
Slope Comp
LDrv
Soft Start Fault Logic
Over Current
200uA
Enable
1.18Vset 1.1Vset
0.9Vset 3011Ablk1-1.1
Figure Simplified block diagram IRU3011
Rev. 12/8/00
4-37
IRU3011
TYPICAL APPLICATION
SYNCHRONOUS OPERATION (Dual Layout with HIP6004B)
Vcore
NC/Gnd HDrv Boot CS17 LDrv NC/Sen V5/Comp Ct/Rt
IRU3011
Vcc3 VID4 VID3 VID2 VID1 VID0
3011app1-1.3
Power Good
Typical application IRU3011 board DC-DC converter providing Core supply microprocessor
Table components that need modified make dual layout work IRU3011and HIP6004B
Part IRU3011
HIP6004B
Short
Open
Harris parts list value
4-38
Rev. 12/8/00
IRU3011
IRU3011 HIP6004B Dual Layout Parts List Desig C2,9 R2,3,4 Description MOSFET MOSFET Inductor Inductor Capacitor, Electrolytic Capacitor, Ceramic Capacitor, Electrolytic Capacitor, Ceramic Capacitor, Ceramic Capacitor, Ceramic Capacitor, Ceramic Capacitor, Electrolytic Capacitor, Ceramic Capacitor, Ceramic Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Part IRL3103s, TO-263 package IRL3103D1S, TO-263 package L=1µH, 5052 core with turns 1.0mm wire L=2.7µH, 5052B core with turns 1.2mm wire 10MV470GX, 470uF,10V 1µF, 0603 10MV1200GX, 1200uF,10V 220pF, 0603 1µF, 0805 150pF, 0603 1000pF, 0603 6MV1500GX, 1500µF, 6.3V 0.1µF, 0603 4.7µF, 1206 3.3k, 0603 4.7, 1206 0603 10k, 0603 0603 220, 0603 330, 0603 22k, 0603 0603 Manuf Micro Metal Micro Metal Sanyo Sanyo
Sanyo
Note R10, R11, C15, Vcore higher level shift reduce transient voltage
Rev. 12/8/00
4-39
IRU3011
APPLICATION INFORMATION
example calculate components application circuit given below. Assuming, sets output conditions that this regulator must meet, Vo=2.8V Io=14.2A, Vo=185mV, Io=14.2A Vo=2V Io=14.2A, Vo=140mV, Io=14.2A regulator design will done such that meets worst case requirement each condition. Output Capacitor Selection 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 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 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.
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. 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 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 device total change from light load full load 14A, then output voltage measured resistor divider which also connected output capacitors this case,
4-40
Rev. 12/8/00
IRU3011
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 wounded 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 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 Heatsink Selection Selection heat sink based maximum allowable junction temperature MOSFETS. Since previously selected maximum RDS(on) 125°C, then must keep junction below this temperature. Selecting TO-220 package gives jc=1.8°C/W (From venders' datasheet) assuming that selected heatsink black anodized, heat-sink-to-case thermal resistance cs=0.05°C/W, maximum heat sink temperature then calculated 3.82 (1.8 0.05) With maximum heat sink temperature calculated previous step, heat-sink-to-air thermal resistance (sa) calculated follows:
Rev. 12/8/00
4-41
IRU3011
Assuming Ta=35 Temperature Rise Above Ambient T/Pd 3.82 °C/W Next, heat sink with lower than calculated previous step must selected. this simply look graphs "Heat Sink Temp Rise Above Ambient" "Power Dissipation" given heatsink manufacturers' catalog select heat sink that results lower temperature rise than calculated previous step. following heat sinks from AAVID Thermalloy meet this criteria. Thermalloy AAVID Part 6078B 577002
Where: Where
Timing Capacitor Switching Frequency
200kHz:
Switcher Output Voltage Adjust 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 device 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, Rtop 100, bottom resistor, calculated. example, voltage setting 2.8V desired output under light load 2.835V, then calculated using following formula: 100*{Vdac /(Vo 1.004*Vdac)} 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. Soft Start Capacitor Selection
Following same procedure Schottky diode results heatsink with °C/W. Although possible select slightly smaller heatsink, simplicity same heatsink high side MOSFET also selected synchronous MOSFET. Switcher Current Limit Protection controller 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 from previous selection, maximum MOSFET RDS(on)=19m, then current sense resistor, calculated Vcs=IcL*RDS =22*0.019=0.418V Where: Ib=200µA internal current setting device Switcher Timing Capacitor Selection switching frequency programmed using external timing capacitor. value approximated using equation below:
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
4-42
Rev. 12/8/00
IRU3011
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. Switcher External Shutdown best shutdown part 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 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 input capacitors high side MOSFET, close each other possible Place synchronous MOSFET, switch MOSFET, close each other possible with intention that connection between source drain shortest possible length. Place snubber between Place output inductor, output capacitors, between MOSFET load with output capacitors distributed along slot close Place bypass capacitors, right next pins. next 12V, next Place such that output drives, pins relatively short distance from gates output voltage adjusted, place resistor dividers close feedback pin. Note Although, device does require resistor dividers feedback directly connected output, they used outputs slightly higher account output drop load trace resistance. application note. Place timing capacitor close soft start capacitor close 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. Connect grounds ground plane using direct vias ground plane. large inductance/low impedance plane connect following connections either using component side solder side. Drain Source Drain drain output capacitors, slot Input filter
Connect rest components using shortest connection possible.
Rev. 12/8/00
4-43
IRU3011
Notes
4-44
Rev. 12/8/00

5-BIT PROGRAMMABLE SYNCHRONOUS BUCK CONTROLLER Dual layout compat

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