TPS54900

SLVS405 – OCTOBER 2001

4

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Terminal Functions

TERMINAL

PIN DESCRIPTION

FUNCTIONAL DESCRIPTION

NAME

NO.

PIN DESCRIPTION

FUNCTIONAL DESCRIPTION

LX0

1

Channel 0 switch output

Output to inductor and catch diode

LX1

2

Channel 1 switch output

Output to inductor and catch diode

GND

3

Ground

Power and Analog Ground

SFS

4

Frame sync input

Read/write frame start strobe

SDI

5

Serial data in

8 bit address/16–bit data word command input

EN

6

Enable

EN < VIL: Disable all channels,

EN > VIH: Enable activates outputs (see text)

FB0

7

Channel 0 feedback input

FB1

8

Channel 1 feedback input

Feedback from L C filter output

FB2

9

Channel 2 feedback input

Feedback from L–C filter output

FB3

10

Channel 3 feedback input

CBS

11

Channel bank select

Assigns internal channels to respond to serial address bit ADR2 = 0 when CBS < VIL,

or to ADR2 = 1 when CBS > VIH

SCLK

12

Serial clock input

Serial clock/synchronization signal

SDO

13

Serial data out

Status data output signal, open drain

VIN

14

Input supply voltage

Chip supply and channel 0–3 switch input

LX2

15

Channel 2 switch output

Output to inductor and catch diode

LX3

16

Channel 3 switch output

Output to inductor and catch diode

functional block diagram

UVLO

Bias

Oscillator,

Clock & Ramp

Generator

Bandgap

Reference

Serial

Command

Interface

Output Status

VIN

GND

EN

CBS

SFS

SCLK

SDI

SDO

PWM Ramp

DACV0

DACV1

DACV2

DACV3

FB3

FB2

FB1

FB0

LX3

LX2

LX0

LX1

Reset

Thermal

Shutdown

Shutdown

PWM

Control

DACs

Programming

Registers

ST

ILIM

ILIM

ILIM

ILIM