LM27262

Features:

Compatible with "VRD10 Voltage Regulation Specification" for Intel Pentium 4 and Prescott Processors
Supports Intel SpeedStep(TM) technology (Geyserville-III(TM)), which enables real-time dynamic switching of the CPU core voltage and the CPU clock frequency
Uses external gate drivers (LM2724) for maximum layout flexibility and noise immunity
Fixed frequency PWM architecture
Pin selectable internal or external voltage reference
0.5% core voltage set-point accuracy when using external voltage reference
0.9% accurate internal bandgap reference
2-, 3- or 4-phase operation
Out-of-phase switching reduces input ripple current, thereby minimizing input capacitor requirements
VID-code programmable output voltage range of 0.8375V through 1.6000V
User programmable, low loss, load line slope
User programmable Standard VID offset
User programmable VCORE slew rate
5V power rail Under Voltage Lock Out (UVLO)
Over Voltage Protection (OVP), Under Voltage Protection (UVP), and Over Current Protection (OCP) to defend against potentially catastrophic events
User programmable fault latch that can be used to disable the regulator in the event a power system fault
Very fast transient response
VID-transition masked PWRGOOD output
True-differential current sensing for each phase ensures accurate load current sharing
User programmable cycle-by-cycle current limit


Application

Server and desktop computer CPU core power supplies requiring a 2, 3- or 4-phase voltage regulator delivering up to 100A
Transportable notebook computers using desktop CPUs
Low cost transportable notebook computers using 2- or 3-phase designs


Pinout




Specifications

V_CC 5V ......................................-0.3V to 7V
PHASES, IREF, VSTDOS,
VPROG,
SLADJ1, SLADJ2, VREF,
REFINT,
CLIMADJ, VCORE, COMP,
VFB,
VILx, VIHx, SOFTCAP,
PWRGD,
VIDPGD, VID0-VID5,
VRON .......................-0.3V to V_CC 5V + 0.3V
Differential Voltage (VILx
VIHx)....................................................... 1V
Ambient Storage Temp.
Range................................. -65?C to +150C
Junction Temperature ...........-20C to +150C
Minimum ESD Rating
(Note 4) ..............................................±2kV
Human Body Model 100pF
Machine Model .....................................1.5 k
Soldering Dwell Time,
Temperature (Note 3)
Wave ..........................................4sec, 260C
Infrared ....................................10sec, 240C
Vapor Phase............................. 75sec, 219C


Description

The LM27262 is a versatile synchronous buck voltage regulatorcontrollerdesignedaccordingtotheIntelVRD10Speci- fication. It's a fixed-frequency voltagmode control PWM with average current modulation of the reference voltage to achieve the desired output impedance. This approach imparts a pseudo current mode behavior to the control loop. The part provides the control for a voltage regulator consisting of either 2-, 3- or 4-phases to provide power to a desktop
CPU. Pulse-by-pulse phase current balancing ensures accurate current sharing. CPU core currents of over 90A can be supported without requiring significant over design of the power path. The LM27262 contains a precision 6-bit digital- to-analog converter (DAC) that uses a VID-code provided by the CPU to program the desired CPU core voltage. The regulator output voltage can be dynamically adjusted by changing the VID-code "on the fly".

The part is intended to provide all the specified functions laid out in the VRD-10 specification, making it as simple as possible for the user to realize a fully compliant CPU core supply for Intel's Pentium(TM)4 and Prescott(TM) processors. The LM27262 is available in a 48-lead TSSOP package and in a 48-lead LLP package.