6-Bit Programmable 2-/3-Phase

Synchronous Buck Controller

ADP3197

Rev. 0

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FEATURES

Selectable 2-phase and 3-phase operation at up to 1 MHz

per phase

±10 mV worst-case differential sensing error over

temperature

Logic-level PWM outputs for interface to external high

power drivers

Enhanced PWM flex mode for excellent load transient

performance

Active current balancing between all output phases

Built-in power good/crowbar blanking that supports

on-the-fly VID code changes

Digitally programmable 0.3750 V to 1.55 V output

Programmable short-circuit protection with

programmable latch-off delay

APPLICATIONS

Desktop PC power supplies for

Next-generation AMD processors

Voltage regulator modules (VRM)

GENERAL DESCRIPTION

switching regulator controller optimized for converting a 12 V

main supply into the core supply voltage required by high perform-

ance, Advanced Micro Devices, AMD processors. It uses an

internal 6-bit digital-to-analog converter (DAC) to read a voltage

identification (VID) code directly from the processor, which is

used to set the output voltage between 0.3750 V and 1.55 V. It uses

a multimode pulse-width modulation (PWM) architecture to

drive the logic level outputs at a programmable switching

frequency that can be optimized for VR size and efficiency.

The phase relationship of the output signals can be programmed

to provide 2-phase or 3-phase operation, allowing for the

construction of up to three complementary buck switching stages.

The ADP3197 supports a programmable slope function to adjust

the output voltage as a function of the load current so it is always

optimally positioned for a system transient. This can be disabled

by connecting the LLSET pin to the CSREF pin.

The ADP3197 also provides accurate and reliable short-circuit

protection, adjustable current limiting, and a delayed power-

good output that accommodates on-the-fly output voltage

changes requested by the CPU.

FUNCTIONAL BLOCK DIAGRAM

VCC

PRECISION

REFERENCE

DELAY

–

+

GND

ADP3197

EN

DELAY

ILIMIT

PWRGD

RAMPADJ

RT

PWM2

PWM3

SW3

SW2

SW1

CSREF

CSCOMP

CSSUM

FB

PWM1

VID5 VID4 VID3

VID2

VID0

VID1

COMP

FBRTN

VID DAC

–

+

800mV

–

+

CSREF

2.2V

CURRENT

MEASUREMENT

AND LIMIT

CROWBAR

CURRENT

LIMIT

+

–

CURRENT

BALANCING

CIRCUIT

OD

SS

–

+

IREF

THERMAL

THROTTLING

CONTROL

TTSENSE

VRHOT

LLSET

UVLO

SHUTDOWN

SHUNT

REGULATOR

–

+

DAC – 250mV

OSCILLATOR

SOFT START

CONTROL

10

9

24

15

1

2

31

32

8

7

5

17

3

30

26

25

29

27

28

6

18

13

12

22

21

16

14

4

19

20

23

11

+

–

CMP

+

–

CMP

+

–

CMP

RESET

2-/3-PHASE

DRIVER LOGIC

EN

SET

RESET

RESET

Figure 1.

The ADP3197 has a built-in shunt regulator that allows the part

to be connected to the 12 V system supply through a series resistor.

The ADP3197 is specified over the extended commercial tempera-

ture range of 0°C to 85°C and is available in a 32-lead LFCSP.