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Description

The TL7660 is a CMOS switched-capacitor voltage converter that perform supply-voltage conversions from positive to negative. With only two noncritical external capacitors needed for the charge pump and charge reservoir functions, an input voltage within the range from 1.5 V to 10 V is converted to a complementary negative output voltage of –1.5 V to –10 V. The device can also be connected as a voltage doubler to generate output voltages up to 18.6 V with a 10-V input.

The basic building blocks of the IC include a linear regulator, an RC oscillator, a voltage-level translator, and four power MOS switches. To ensure latch-up-free operation, the circuitry automatically senses the most negative voltage in the device and ensures that the N-channel switch source-substrate junctions are not forward biased.

The oscillator frequency runs at a nominal 10 kHz (for V CC = 5 V), but that frequency can be decreased by adding an external capacitor to the oscillator (OSC) terminal or increased by overdriving OSC with an external clock.