NX2309

4

Rev. 2.0

12/19/05

PIN DESCRIPTIONS

PIN #

PIN SYMBOL

PIN DESCRIPTION

Power supply voltage. A high freq 1uF ceramic capacitor is placed as close as

possible to and connected to this pin and ground pin. The maximum rating of this

pin is 16V.

This pin supplies voltage to high side FET driver. A high freq 0.1uF ceramic

capacitor is placed as close as possible to and connected to this pin and SW

pin.

Power ground.

This pin is the error amplifiers inverting input. This pin is connected via resistor

divider to the output of the switching regulator to set the output DC voltage.

This pin is the output of the error amplifier and together with FB pin is used to

compensate the voltage control feedback loop. This pin is also used as a shut down

pin. When this pin is pulled below 0.2V, both drivers are turned off and internal soft

start is reset.

This pin is connected to source of high side FETs and provide return path for the

high side driver. It is also used to hold the low side driver low until this pin is

brought low by the action of high side turning off. LDRV can only go high if SW is

below 1V threshold .

High side gate driver output.

Low side gate driver output.

LDO controller feedback input. This pin is connected via resistor divider to the out-

put of the switching regulator to set the output DC voltage.If the LDOFB pin is pulled

below 0.4V, an internal comparator after a delay pulls down LDOOUT pin and ini-

tiates the HICCUP circuitry. During the startup this latch is not activated, allowing

the LDOFB pin to come up and follow the soft started Vref voltage.

LDO controller output. This pin is controlling the gate of an external NCH MOSFET.

The maximum rating of this pin is 16V.

5

1

3

8

9

10

2

4

6

7

VCC

BST

GND

FB

COMP

SW

HDRV

LDRV

LDO_FB

LDO_OUT

NOTE1: In actual circuit application, the ENSW pin is used to program converter start up and hysteresis threshold

voltage.

NOTE2: This parameter is guaranteed by design but not tested in production(GBNT).