5-Bit Programmable 2-/3-/4-Phase

Synchronous Buck Controller

ADP3186

Rev. A

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FEATURES

Selectable 2-, 3-, or 4-phase operation at up to 1 MHz

per phase

±1% worst-case differential sensing error over temperature

Logic-level PWM outputs for interface to external high

power drivers

Active current balancing between all output phases

Built-in power good/crowbar blanking supports on-the-fly

VID code changes

5-bit digitally programmable 0.8 V to 1.55 V output

Programmable short-circuit protection with programmable

latch-off delay

APPLICATIONS

Desktop PC power supplies for

AMD Opteron™ processors

VRM modules

GENERAL DESCRIPTION

The ADP3186 is a highly efficient multiphase synchronous

buck switching regulator controller optimized for converting a

12 V main supply into the core supply voltage required by high

performance AMD processors. It uses an internal 5-bit DAC to

read a voltage identification (VID) code directly from the pro-

cessor, which is used to set the output voltage between 0.8 V

and 1.55 V. It uses a multimode PWM architecture to drive the

logic-level outputs at a programmable switching frequency that

can be optimized for VR size and efficiency. The phase relation-

ship of the output signals can be programmed to provide 2-, 3-,

or 4-phase operation, allowing the construction of up to four

complementary buck switching stages.

The ADP3186 includes programmable no-load offset and slope

functions to adjust the output voltage as a function of the load

current, so that it is always optimally positioned for a system

transient. The ADP3186 also provides accurate and reliable

short-circuit protection, adjustable current limiting, and a power

good output that accommodates on-the-fly output voltage

changes requested by the CPU.

The ADP3186 is specified over the commercial temperature

range of 0°C to 85°C and is available in 28-lead TSSOP and

QSOP packages.

FUNCTIONAL BLOCK DIAGRAM

VCC

PRECISION

REFERENCE

SOFT

START

DELAY

UVLO

SHUTDOWN

AND BIAS

OSCILLATOR

GND

CROWBAR

ADP3186

19

28

RT

13

RAMPADJ

14

PWM2

26

8

FB

PWM3

25

PWM4

24

SW1

23

CSSUM

17

CSCOMP

18

SW2

22

SW3

21

SW4

20

CSREF

16

PWM1

VID4

1

VID3

2

VID2

3

VID1

4

6

VID0

5

FBRTN

7

VID

DAC

DAC + 300mV

DAC – 300mV

CSREF

EN

CURRENT

LIMIT

CIRCUIT

CROWBAR

CURRENT

LIMIT

CMP

CMP

CMP

CMP

CURRENT

BALANCING

CIRCUIT

2-/3-/4-PHASE

DRIVER LOGIC

EN

SET

RESET

RESET

RESET

RESET

27

CSREF

2.1V

Figure 1.