Integrated power-amp controller

Dallas Semiconductor has introduced the DS1870, claimed to be the industry's first complete LDMOS power-amp biasing and monitoring device.

It optimally biases two LDMOS power amps over temperature and drain voltage/current variations. It also manages system monitoring.

The level of integration reduces component count, layout area, and speeds up the design of LDMOS power-amp modules.

Dual 256-step potentiometers enable optimal gate-bias operation for two LDMOS power amplifiers. The summation of two lookup table entries controls each potentiometer.

The first lookup table adjusts for temperature variation in 2°C increments, while the second lookup table adjusts for variations in drain voltage (or other external parameters).

The voltage range of the potentiometer output can be adjusted to provide fine resolution control.

Monitoring functionality is enabled by a 12 bit analog-to-digital converter with three muxed analog inputs, plus VCC monitor and temperature sensor.

A fault signal can be generated in response to an out-of-tolerance condition in any of these parameters. In addition, 32 bytes of user EEPROM are available for manufacturing or vendor data.

Communication with the devices is achieved over an I2C interface. Three address pins enable up to eight devices on a common serial bus.

The DS1870 is available in a 16 pin TSSOP, and operates from a 4.5 to 5.5 V supply over a -40 to +95°C temperature range.