3

Functional pin description

GND

Device ground pin.

VIN

Supply voltage. This pin supplies power to the internal analog and digital circuitries when voltage is higher than

VUVLO. Bypass this pin to GND with a 10 μF ceramic capacitor. Input capacitor C1 must be chosen with low ESR

to reduce the input voltage ripple.

VIN_AUX

Supply voltage pin for auxiliary channel. This pin supplies internal switch “S3” and must be always ≤ VIN. It

is recommended to have VIN_AUX present before setting AUX pin to high, to avoid inrush current on VIN_AUX

supply voltage.

Bypass this pin to GND with a ceramic capacitor, see Table 1. Typical external components. Input capacitor C2

must be chosen with low ESR to reduce the input voltage ripple.

SW

Switching output pin. Inductor connection to internal PMOS and NMOS switches.

VOUT

Output voltage sense input pin. It provides the feedback voltage level to the regulation circuitry. 10 µF output

capacitor C3 must be connected close to the pin or through a short trace and should have low ESR to reduce the

output voltage ripple.

EN

Enable pin. A logic low level on this pin disables the device. High level enables the device. Do not leave this pin

floating.

D0, D1, D2

Output voltage selection pins. See Table 7. Output voltage settings for VOUT selection. Do not leave these pins

floating. These pins can be dynamically changed during operation.

PGOOD

Power Good open drain output pin. If used it requires a pull-up resistor to hold a high level signal. High

impedance indicates that VOUT is above proper good threshold.

AUX

Load switch selection pins.

When this pin and EN are both set to high, VOUT_AUX output is enabled. If EN low and AUX High VOUT_AUX is

disabled. Held to ground if auxiliary output (VOUT_AUX) is not used or if it should be disabled.

VOUT_AUX

Auxiliary output pin. 0.6 Ohm switch connect VIN_AUX to this PIN when enabled. 10 µF output capacitor C4

must be connected close to the pin or through a short trace. This output is controlled from a soft-start circuit and it

is not current limited. If unused can be left open.

ST1PS03

Functional pin description

DS13801 - Rev 1

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