Parameter

Symbol Condition

Min

Typ

Max

Units

Input Under Voltage Lockout

Threshold

4.

30

V

Input Under Voltage Lockout

Threshold Hysteresis

210

mV

Soft-Start Current

6

µA

Soft-Start Period

15

ms

Thermal Shutdown

160

°C

PIN FUNCTIONS

Pin #

Name

Description

1

BS

High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET

switch. Connect a 1

0nF or greater capacitor from SW to BS to power the high side switch.

3

SW

Power Switching Output. SW is the switching node that supplies power to the output. Connect

the output LC filter from SW to the output load. Note that a capacitor is required from SW to

BS to power the high-side switch.

4

GND

Ground.

6

COMP

Compensation Node. COMP is used to compensate the regulation control loop. Connect a

series RC network from COMP to GND to compensate the regulation control loop. In some

cases, an additional capacitor from COMP to GND is required.

8

SS

Soft-Start Control Input. SS controls the soft start period. Connect a capacitor from SS to GND

to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 15ms. To disable the

soft-start feature, leave SS unconnected.

2

IN

Power Input. IN supplies the power to the IC, as well as the step-down converter switches.

Drive IN with a 4.75V to 18V power source. Bypass IN to GND with a suitably large capacitor

to eliminate noise on the input to the IC.

5

FB

Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a

resistive voltage divider from the output voltage. The feedback threshold is 0.9

05V.

7

EN

Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on

the regulator, drive it low to turn it off. Pull up with 100kΩ resistor for automatic startup.

Advanced Monolithic Systems http://www.ams-semitech.com

3

AMS1069