NX2147

5

Rev. 1.6

03/09/09

Rev. 1.8

12/28/09

PIN DESCRIPTIONS

PIN NUMBER PIN SYMBOL

PIN DESCRIPTION

This pin is directly connected to the output of the switching regulator and

senses the VOUT voltage. An internal MOSFET with 20ohms rdson dis-

charges the output during turn off.

This pin supplies the internal 5V bias circuit. A 1uF X7R ceramic capacitor is

placed as close as possible to this pin and ground pin.

This pin is connected via resistor divider to VREF_OC pin to set the output

DC voltage from 0.5V to VREF 2.5V.

This pin is a drain of an internal signal MOSFET. When it is connected via

resistor to the VP pin,and the GPIO0 pin is set low, it reduces the VP

voltage by paralleling this resistor to the fixed resistor from VP to GND.

This pin is a drain of an internal signal MOSFET. When it is connected via

resistor to the VP pin,and the GPIO_1 pin is set low, it reduces the VP

voltage by paralleling this resistor to the fixed resistor from VP to GND.

A logic level input signal that controls the D1 pin. A low signal turns the

internal D1 MOSFET on and a High turns it off.

Power ground.

Low side gate driver output.

Provide the voltage supply to the lower MOSFET drivers. Place a high

frequency decoupling capacitor 1uF X5R to this pin.

Reference output voltage. A resistor divider from this pin to VP pin sets the

output voltage. The total resistance from this pin to GND also sets the OCP

threshold voltage. Note that when GPIO0 and GPIO1 pins are high the

reference divider is at its highest voltage. The nominal voltage of Vref is

2.5V.

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

the high side driver. It is also the input of zero current sensing comparator.

High side gate driver output.

This pin supplies voltage to high side FET driver. A high freq 1uF X7R

ceramic capacitor and 2.2ohm resistor in series are recommended to be

placed as close as possible to and connected to this pin and SW pin.

A logic level input signal that controls the D0 pin. A low signal turns the

internal D0 MOSFET on and a High turns it off.

Switching converter enable input. Connect to VCC for PFM/Non synchronous

mode, connected to an external resistor divider equals to 70%VCC for ultra-

sonic, connected to GND for shutdown mode, floating or connected to 2V for

the synchronous mode.

VIN sensing input. A resistor connects from this pin to VIN will set the fre-

quency. A 1nF capacitor from this pin to GND is recommended to ensure the

proper operation.

Analog ground.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

VOUT

VCC

VP

D1

D0

GPIO1

PGND

LDRV

PVCC

VREF_OC

SW

HDRV

BST

GPIO0

ENSW/

MODE

TON

PAD