AN1330

Pin functions

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1

Pin functions

1.1

Pin description

1.2

Block diagram

Figure 4.

Block diagram

Table 1.

Pin description

N.

Name

Description

1

OUT

Regulator output

2

SYNC

Master/slave synchronization. When open, a signal synchronous with the turn-OFF of

the internal power is present. When connected to an external signal at a frequency

higher than the internal one, then the device is synchronized by the external signal.

Connecting the SYNC pins of two devices, the one with the higher frequency works as

master and the other one works as slave.

3INH

A logical signal (active high) disables the device. With an IHN higher than 2.2 V the

device is OFF and with an INH lower than 0.8 V, the device is ON.

If INH is not used the pin must be grounded. When it is open, an internal pull-up

disables the device.

4

COMP E/A output to be used for frequency compensation

5FB

Step-down feedback input. Connecting the output voltage directly to this pin results in

an output voltage of 1.235 V. An external resistor divider is required for higher output

voltages (the typical value for the resistor connected between this pin and ground is

4.7 k).

Reference voltage of 3.3 V. No filter capacitor is needed for stability

7

GND

Ground

Unregulated DC input voltage.

INHIBIT

VOLTAGES

MONITOR

PEAK TO PEAK

CURRENT LIMIT

THERMAL

SHUTDOWN

E/A

PWM

1.235V

+

-

-

+

OSCILLATOR

D

Ck

Q

FREQUENCY

SHIFTER

TRIMMING

SUPPLY

1.235V

3.5V

DRIVER

BUFFER

LPDMOS

POWER

FB

SYNC

COMP

INH

VREF

GND

OUT

VCC

AM00003v1