LM828

The LM828 from Texas Instruments is a CMOS charge-pump voltage converter designed to invert a positive input supply voltage to a corresponding negative output voltage. It accepts an input voltage range from +1.8V to +5.5V and generates an output voltage between -1.8V and -5.5V. This device is capable of providing up to 25 mA of output current, utilizing two low-cost capacitors for its operation.

The LM828 operates at a switching frequency of 12 kHz, which helps to minimize output resistance and voltage ripple. With a typical operating current of only 40 µA and an efficiency greater than 96% for most loads, it is well-suited for battery-powered applications. The converter features a typical output impedance of 20 Ω and achieves up to 97% conversion efficiency at 5 mA.

This voltage converter is housed in a compact SOT-23 package, making it suitable for space-constrained designs. Its ability to invert voltage efficiently makes it ideal for applications such as cellular phones, pagers, PDAs, operational amplifier power supplies, interface power supplies, and handheld instruments where a negative voltage rail is required from a positive supply.

The device has an absolute maximum supply voltage rating of 5.8V and can handle continuous output currents up to 50 mA. The operating junction temperature range is from -40°C to 85°C.