IR3508

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October 27, 2008

DATA SHEET

DESCRIPTION

implement a power solution for the latest high performance CPUs and ASICs. The “Control” IC provides

overall system control and interfaces with any number of “Phase” ICs which each drive and monitor a single

expensive, and easier to design while providing higher efficiency than conventional approaches.

The IR3508 disables its current sense amplifiers when entering power savings mode. The recommended use

for these Phase ICs is for applications without adaptive voltage positioning where two or more power stages

will be operating in power savings mode.

FEATURES IR3508 PHASE IC

x Power State Indicator (PSI) interface provides the capability to maximize the efficiency at light loads.

x Anti-bias circuitry

x 7V/2A gate drivers (4A GATEL sink current)

x Support converter output voltage up to 5.1 V (Limited to VCCL-1.4V)

x Loss-less inductor current sensing

x Phase delay DFF bypassed during PSI assertion mode to improve output ripple performance

x Over-current protection during PSI assertion mode operation

x Feed-forward voltage mode control

x Integrated boot-strap synchronous PFET

x Only four external components per phase

x 3 wire analog bus connects Control and Phase ICs (VID, Error Amp, IOUT)

x 3 wire digital bus for accurate daisy-chain phase timing control without external components

x Debugging function isolates phase IC from the converter

x Self-calibration of PWM ramp, current sense amplifier, and current share amplifier

x Single-wire bidirectional average current sharing

x Small thermally enhanced 20L 4 X 4mm MLPQ package

x RoHS compliant

APPLICATION CIRCUIT

VOUT-

12V

CLKIN

PHSOUT

PHSIN

VCCL

VOUT+

IOUT

DACIN

EAIN

PSI

CCS

CVCCL

DACIN

3

GATEH

14

VCCL

12

BOOST

13

PHSIN

5

IOUT

1

SW

15

LGND

4

PSI

2

NC

11

IR3508

COUT

L

RCS

CBST

Figure 1 Application Circuit