LTC1429

Obsolete - Datasheet For Information Purposes Only. Contact Analog Devices for Potential Replacement

The LTC1429 is a switched-capacitor voltage inverter designed to provide a regulated negative voltage from a single positive supply and permits clock synchronization in noise sensitive systems. The LTC1429CS operates from a single 3V to 8V supply and provides an adjustable output voltage from -1.25V to -8V. An on-chip resistor string allows the LTC1429CS to be configured for output voltages of -3.5V, -4V,-4.5V or -5V. The LTC1429CS8 is optimized for applications which require a fixed -4V output from a 5V supply and requires only a single external 0.1µF flying capacitor. The LTC1429CS requires one or two external 0.1µF capacitors, depending on input voltage. Both versions require additional external input and output bypass capacitors. An optional compensation capacitor at ADJ/COMP can be used to reduce the output voltage ripple.

Each version of the LTC1429 guarantees output regulation of 5%. The LTC1429 includes an open-drain REG output which pulls low when the output is within 5% of the set value. Output ripple is typically as low as 5mV. The LTC1429 requires an external clock applied to the SYNC/SD for normal operation and consumes a typical quiescent current of 600µA. Holding the SYNC/SD either high or low brings the device into shutdown and the supply current drops to 0.2µA. For applications which don’t have a clock signal available, the LTC1261 provides the same functionality with an internal oscillator. For applications which require output ripple below 1mV, see the LTC1550/LTC1551. The LTC1429CS is available in a 14-pin SO package and the LTC1429CS8 is available in an 8-pin SO package.

Applications

• GaAs FET Bias Generators
• Negative Supply Generators
• Battery Powered Systems
• Single Supply Applications