L7983 datasheet(4/43 Pages) STMICROELECTRONICS

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Pin settings

Figure 3. Pin connection (top view)

VOUT/FB

EXPOSED

PAD TO

GND

VBIAS

VCC

FSW

LNM/LCM

GND

VIN

EN/UVLO

RST

Table 1. Pin description

N°

Description

VOUT/FB

Output voltage sensing. This pin operates as VOUT or FB accordingly with

selected part number:

•

VOUT is output voltage sensing with selected internal voltage divider.

•

FB is output voltage sensing with external resistor divider.

VBIAS

Input supply of the integrated LDO. Typically connected to the regulated output

voltage or an auxiliary rail to increase the efficiency at light load. Connect to GND

if not used or bypass with a 100 nF ceramic capacitor if supplied by the output

voltage or by an auxiliary rail.

VCC

Output of the integrated LDO that supplies the embedded analog circuitry.

Connect a ceramic capacitor (470 nF typ.) to filter internal voltage reference.

FSW

Switching frequency programming pin. Connect an external resistor to VCC or

GND.

LNM/LCM

Dynamic pin selection between Low Consumption Mode (LCM, active low) and

Low Noise Mode operation (LNM, active high). This pin can also be used for

synchronization with an external clock (clock-in function).

RST

Active low open collector output for output monitoring and power-up reset

sequencing. RST is driven in low impedance when the output voltage is out of

regulation and released once the output voltage becomes valid.

EN/UVLO

Active high enable pin, VIN compatible. It can be exploited with an external

resistor divider to adjust the input undervoltage lockout (UVLO).

VIN

DC input voltage

Switching node

GND

Ground

E.P.

Exposed pad must be connected to GND

L7983

Pin settings

DS13354 - Rev 1

page 4/43

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