ST1S31 datasheet(4/35 Pages) STMICROELECTRONICS

4 / 35 page

Pin settings

ST1S31

4/35

DocID022998 Rev 4

Pin settings

1.1

Pin connection

Figure 2. Pin connection (top view)

1.2

Pin description

Table 1. Pin description

No.

Type

Description

VINA

Unregulated DC input voltage

2EN

Enable input. With EN higher than 1.5 V the device is ON and with EN

lower than 0.5 V the device is OFF.

3FB

Feedback input. Connecting the output voltage directly to this pin the

output voltage is regulated at 0.8 V. To have higher regulated voltages an

external resistor divider is required from VOUT to the FB pin.

AGND

Ground

5PG

Open drain Power Good (POR) pin. It is released (open drain) when the

output voltage is higher than 0.92 * VOUT with a delay of 170 s. If the

output voltage is below 0.92 * VOUT, the POR pin goes to low impedance

immediately. If not used, it can be left floating or to GND.

VINSW

Power input voltage

Regulator output switching pin

PGND

Power ground

ePAD

(VFDFPN package only) exposed pad connected to ground assuring

electrical contact and heat conduction.

ST1S31 Datasheet(PDF) 4 Page - STMicroelectronics