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Design DocumentAnalog

Analog DC064B Pentium Processor Switching Regulator Power Module

High-efficiency 5V to 3.3V/3.5V switching regulator module for Intel Pentium VR/VRE processors featuring the LTC1266 and LT1431.

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Overview

Demonstration Circuit 064B is a power supply module compliant with Intel specifications for powering Pentium processors, including VR and VRE versions. It operates from a 5.0V ±5% input and provides jumper-selectable output voltages of 3.30V, 3.383V (VR), and 3.525V (VRE). The circuit design utilizes the LTC1266 current-mode synchronous buck switching regulator controller and the LT1431 precision shunt regulator as a high-gain error amplifier and reference. This architecture enables tight static tolerances of 0.65% and fast transient response. The module uses all N-channel MOSFETs, operates at approximately 200kHz to minimize inductor size, and maintains efficiency above 90% across most of the load range. It is designed to interface via a standard 30-pin header.

Use Cases

  • Powering Intel Pentium VR and VRE processors
  • High-efficiency 5V step-down voltage regulation
  • Intel-compliant power module design
  • Synchronous buck regulator evaluation with N-channel MOSFETs

Topics

LTC1266
LT1431
Pentium Processor
Switching Regulator
Synchronous Buck
Power Module
DC064B
VRM
Si4410DY
Si9410DY

Referenced Parts

MBR0520LT1

Motorola

D1,D2 2 MBR0520LT1 Diode, Schottky, 20V, 0.5A MOTOROLA

MBRS130LT3

Motorola

D3 1 MBRS130LT3 Diode, Schottky, 30V, 1A MOTOROLA

SNT-100-BK-T

Samtec

JP2 0 SNT-100-BK-T Shunt, .100cc, Optional SAMTEC

532956-5

AMP

JP1 1 532956-5 Con., Recept, 30-Pin, 2-Row AMP

CR32-100J-T

AVX

R5 1 CR32-100J-T Res., SMT-1206, 10Ω, 5% AVX

CR32-101J-T

AVX

R3,R4 2 CR32-101J-T Res., SMT-1206, 100Ω, 5% AVX

12065C104ZAT2A

AVX

C12 1 12065C104ZAT2A Cap., X7R, .1μF, 50V, 20% AVX

12065C501MAT2A

AVX

C14 1 12065C501MAT2A Cap., X7R, 500pF, 50V, 20% AVX

CR32-333J-T

AVX

R6 1 CR32-333J-T Res., SMT-1206, 33kΩ, 5% AVX

627V100

BI Technologies

R1 1 627V100 Res., Network BI TECH

CTX3-6-52

Coiltronics

L1 (Note 1) 1 CTX3-6-52 Inductor, Toroid, 3μH COILTRONICS

WSL-2512-0.015-1%

Dale

R2 1 WSL-2512-0.015-1% Res., SMT-2512, 0.015, 1W, 1% DALE

LT1431CS8

Linear Technology

U2 1 LT1431CS8 I.C., SO8, LT1431, Prog Ref LTC

LTC1266CS16

Linear Technology

U1 1 LTC1266CS16 I.C., SO16, LTC1266, Sw-Reg LTC

Si4410DY

Siliconix

Q1 1 Si4410DY Xistor, MOSFET, Si4410, SO-8 SILICONIX

Si9410DY

Siliconix

Q2 1 Si9410DY Xistor, MOSFET, Si9410, SO-8 SILICONIX

51-656

Gowanda Electronics

Note 1. Alternate source: Gowanda Electronics Part # 51-656.

10V

AVX

*Assumes 6 each, 100μF, 10V, AVX type TPS tantalum capacitors or equivalent and 10 each, 1μF 1206 ceramics at the load.

25V

AVX

C11,15 2 12063G105ZAT2A Cap., Y5V, 1μF, 25V AVX (803) 946-0362

2.0V

Maxim

amplifier output to its 2.0V maximum. In this configura-