Ver: 1.4

May 19, 2006

TEL: 886-3-5788833

http://www.gmt.com.tw

7

G5910

Global Mixed-mode Technology Inc.

Pin Descriptions

PIN

NAME

FUNCTION

1

VOUT

Regulated output pin. Bypass this pin to ground with at least 6.8µF low ESR capacitor

2

GND

Ground connection

3

SHDN

Shutdown input. Active low signal disables the converter.

4

C-

Flying capacitor negative terminal

5

VIN

Input supply pin. Bypass this pin to ground with at least 6.8µF low ESR capacitor

6

C+

Flying capacitor positive terminal

Detailed Description

The G5910 uses a switched capacitor charge pump

to boost an input voltage to a regulated output volt-

age. Through an internal resistor divider network

the output regulation is achieved by sensing the

charge pump output voltage. When the divided

output drops below a preset trip point that con-

trolled by an internal comparator a switched dou-

bling circuit is enabled. The charge pump switch

cycling enables four internal switches at two

non-overlapping phases. During the first phase,

switches S1 and S4 are switched on (short) and

switch S2 and S3 are off (open). The flying capaci-

S1 and S4 are turned off (open), S2 and S3 are

turned on (short). During the first phase the low

GND. During the second phase, the flying capacitor

nected to output through a switch. For each cycle

from a lower voltage to a higher voltage. This cycle

repeats itself until the output node voltage is high

enough to exceed the preset input threshold of the

control comparator. When the output voltage ex-

ceeds the internal trip point voltage level, the

switching cycle stops and the charge pump circuit is

placed in an idle state. The closed loop feed back

system containing the voltage sense circuit and

control comparator allows the G5910 to provide a

regulated output voltage and output load current.

An integrated oscillator within the control circuit

block creates the switching signal that drives the

charge pump. The free running charge pump

switching frequency is approximately 1MHz. The

G5910 has complete output short circuit and ther-

mal protection to safeguard the device under ex-

treme operating conditions. When output voltage is

short to ground, the switches S1, S4, and S3 are

turned on with limited current of 220mA. After the

short circuit condition has been released and output

voltage rises above a threshold voltage, the G5910

will go into normal operation mode. An internal

thermal protection circuit senses die temperature

and will shut down the device if the internal junction

charge pump will remain disabling until the fault

condition is relieved.