TPS54873

SLVS444 – OCTOBER 2002

www.ti.com

5

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

AGND

VSENSE

COMP

PWRGD

BOOT

PH

PH

PH

PH

PH

PH

PH

PH

PH

RT

SYNC

SS/ENA

VBIAS

VIN

VIN

VIN

VIN

VIN

PGND

PGND

PGND

PGND

PGND

PWP PACKAGE

(TOP VIEW)

THERMAL

PAD

TERMINAL FUNCTIONS

TERMINAL

DESCRIPTION

NAME

NO.

DESCRIPTION

AGND

1

Analogground. Return for compensation network/output divider, slow-start capacitor, VBIAS capacitor, RT resistor and

SYNC pin. Connect PowerPAD to AGND.

BOOT

5

Bootstrap output. 0.022-

µF to 0.1-µF low-ESR capacitor connected from BOOT to PH generates floating drive for the

high-side FET driver.

COMP

3

Error amplifier output. Connect frequency compensation network from COMP to VSENSE

PGND

15–19

Power ground. High current return for the low-side driver and power MOSFET. Connect PGND with large copper areas

to the input and output supply returns, and negative terminals of the input and output capacitors. A single point connection

to AGND is recommended.

PH

6–14

Phase output. Junction of the internal high-side and low-side power MOSFETs, and output inductor.

PWRGD

4

Power good open drain output. High when VSENSE

≥ 90% Vref, otherwise PWRGD is low. Note that output is low when

SS/ENA is low, or the internal shutdown signal is active.

RT

28

Frequency setting resistor input. Connect a resistor from RT to AGND to set the switching frequency. When using the

SYNC pin, set the RT value for a frequency at or slightly lower than the external oscillator frequency.

SS/ENA

26

Slow-start/enable input/output. Dual function pin which provides logic input to enable/disable device operation and

capacitor input to externally set the start-up time.

SYNC

27

Synchronization input. Dual function pin which provides logic input to synchronize to an external oscillator or pin select

between two internally set switching frequencies. When used to synchronize to an external signal, a resistor must be

connected to the RT pin.

VBIAS

25

Internalbias regulator output. Supplies regulated voltage to internal circuitry. Bypass VBIAS pin to AGND pin with a high

quality, low-ESR 0.1-

µF to 1.0-µF ceramic capacitor.

VIN

20–24

Input supply for the power MOSFET switches and internal bias regulator. Bypass VIN pins to PGND pins close to device

package with a high quality, low-ESR 10-

µF ceramic capacitor.

VSENSE

2

Error amplifier inverting input. Connect to output voltage through compensation network/output divider.