GS7660

Vishay

formerly General Semiconductor

Document Number 74819

www.vishay.com

24-May-02

5

Pin Description

Pin

Name

Function

BOOST

1

When the oscillator is driven externally, BOOST has no effect and should be left open.

N.C.

No Connection

2

CAP+

Connection to positive terminal of Charge-Pump Capacitor

3

GND

Ground. For most applications, the positive terminal of the reservoir capacitor is connected to this pin.

4

CAP–

Connection to negative terminal of Charge-Pump Capacitor

Negative Voltage Output. For most applications, the negative terminal of the reservoir capacitor is

connected to this pin.

6

LV

Low-Voltage Operation. Connect to ground for supply voltages below 3.5V.

7

OSC

Oscillator Control Input. Connecting an external capacitor reduces the oscillator frequency.

Detailed Description

The GS7660 is a charge-pump voltage converter. The

basic operations is as follows: Switch pairs S1, S2 and S3,

S4 (Fig.7) are alternately closed and opened at the rate of

the oscillator frequency divided by two.

During the first half of the cycle, when S1 and S2 are

closed and S3 and S4 are open, bucket capacitor C1 is

charged by input voltage. During the second half of the

cycle, when the switches assume the opposite state,

capacitor C1 is connected in parallel with output capacitor

C2 and any voltage differential causes a transfer of charge

from C1 to C2. This process will continue until the voltage

In normal operation, the output voltage will be less than

being discharged by the load.

S1

S2

S3

S4

C1

C2

Fig. 7 – Ideal Voltage Inverter