LM3103

SNVS523E – SEPTEMBER 2007 – REVISED NOVEMBER 2009

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Typical Application

Connection Diagram

Figure 1. 16-Lead Plastic HTSSOP

Package Number PWP0016A

PIN DESCRIPTIONS

Pin

Name

Description

Application Information

1, 2

VIN

Input supply voltage

Supply pin to the device. Nominal input range is 4.5V to 42V.

3, 4

SW

Switch Node

Internally connected to the source of the main MOSFET and the drain of the synchronous

MOSFET. Connect to the output inductor.

5

BST

Connection for

Connect a 33 nF capacitor from the SW pin to this pin. This capacitor is charged through an

bootstrap capacitor

internal diode during the main MOSFET off-time.

6

AGND

Analog Ground

Ground for all internal circuitry other than the PGND pin.

7

SS

Soft-start

A 70 µA internal current source charges an external capacitor of larger than 22 nF to provide

the soft-start function.

8

NC

No Connection

This pin should be left unconnected.

9, 10

GND

Ground

Must be connected to the AGND pin for normal operation. The GND and AGND pins are not

internally connected.

11

FB

Feedback

Internally connected to the regulation and over-voltage comparators. The regulation setting is

0.6V at this pin. Connect to feedback resistors.

12

EN

Enable pin

Internal pull-up. Connect to a voltage higher than 1.6V to enable the device.

13

RON

On-time Control

An external resistor from the VIN pin to this pin sets the main MOSFET on-time.

14

VCC

Startup regulator

Nominally regulated to 6V. Connect a capacitor of larger than 1 µF between the VCC and

Output

AGND pins for stable operation.

15, 16

PGND

Power Ground

Synchronous MOSFET source connection. Tie to a ground plane.

DAP

EP

Exposed Pad

Thermal connection pad. Connect to the ground plane.

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

2

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