ST777/778/779

2/11

ABSOLUTE MAXIMUM RATINGS

Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is

not implied.

ORDERING CODES

CONNECTION DIAGRAM

PIN CONNECTIONS

THERMAL DATA

Symbol

Parameter

Value

Unit

DC Input Voltage to GND

-0.3 to +7

V

LX

Switch off Pin Voltage

-0.3 to +7

V

Switch on Pin Voltage

30 sec short to IN or OUT

OUT, SHDN

Output, Shutdown Voltage

-0.3 to +7

V

AGND to PGND

Analog and Power Ground

-0.3 to +0.3

V

FB

FB Pin Voltage

-0.3 to (OUT+0.3)

V

550

mW

344

Storage Temperature Range

-40 to 150

°C

Operating Ambient Temperature Range

0to85

°C

TYPE

DIP-8

SO-8

ST777

ST777ACN

ST777ACD

ST778

ST778ACN

ST778ACD

ST779

ST779ACN

ST779ACD

Pin No.

SYMBOL

NAME AND FUNCTION

1

ILIM

Sets switch current limit input. Connect to IN for 1A current limit. A resistor from ILIM to IN

sets lower peak inductor currents.

2

IN

Input from battery

3

AGND

Analog ground. Not internally connected to PGND.

4

PGND

Power ground. Must be low impedance; solder directly to ground plane or star ground.

Connect to AGND, close to the device.

5

LX

Collector of 1A NPN power switch and emitter of Sinchronous Rectifier PNP.

6

OUT

Voltage Output. Connect filter capacitor close to pin.

7SHDN

Shutdown input disables power supply when low. Also disconnets load from input. Threshold

8

SEL/N.C./FB - Selection pin for 3/3.3V version (778);

- Not internally connected for 5V version (777);

- Feedback pin for adjustable version (779).

Symbol

Parameter

DIP-8

SO-8

Unit

Thermal Resistance Junction-ambient

100

160

°C/W