General Description

The TC1142 generates a regulated negative voltage from -3V to -5V at 20mA from an input of 2.5V to 5.5V, using only three external capacitors. Other boost/buck switching regulators must use an inductor, which is larger and radiates EMI. An internal voltage comparator inhibits the charge pump when VOUT is more negative than the regulated value (per the ordering option). The values of flying capacitors C1 and C2 are chosen to be less than COUT in order to reduce the ripple generated from regulating VOUT in this manner. The TC1142 also can be used as a -1x buck regulator by omitting C2, and connecting the C2 pin to VOUT.

Features

• Input Range 2.5V to 5.5V

• Regulated Output Options from -3.0 to -5.0V

• Output Current 20mA (max)

• 200kHz Internal Oscillator Frequency

• External Synchronizing Clock Input

• Logic Level Shutdown

- 1µA (max) Supply Current

• Available in 8-Pin MSOP Package

Applications

• Cellular Phones

• Battery Powered/Portable Equipment