GENERAL DESCRIPTION

The AD7294 contains all the functions required for general purpose monitoring and control of current, voltage, and temperature integrated into a single-chip solution. The part includes low voltage (±200 mV) analog-input sense amplifiers for current monitoring across shunt resistors, temperature-sense inputs, and four uncommitted analog input channels multiplexed into a 200 kSPS SAR ADC. An internal low ppm reference is provided to drive both the DAC and ADC. Four 12-bit DACs provide the outputs for voltage control. The AD7294 also includes limit registers for alarm functions. The part is designed on a high voltage DMOS process for a high voltage compliance, 48 V on the current-sense inputs, and up to 15 V DAC output voltage.

The part is ideal for bias current control of the power transistors used in power amplifiers employed in CDMA, GSM, EDGE, and UMTS cellular base stations.

The DACs provide digital control with 1.2 mV resolution to control the bias currents of the power transistors. They can also be used to provide control voltages for variable gain amplifiers or impedance match networks in the main signal chain. Thermal diode based temperature sensors are incorporated to compensate for temperature effects. The ADC monitors the high-side current and temperature. All this functionality is provided in a 56-lead LFCSP package and a 64-lead TQFP package operating over a temperature range of −40°C to +105°C.

FEATURES

  4-channel 12-bit DAC

     Guaranteed monotonic

     10 μs settling time

     10 mA sink and source capability

     Offset in for range adjustment

     Output span: 5 V in 0 to 15 V range

  9-channel, 12-bit ADC

     200 kSPS throughput

     Input range: 0 to VREF, 0 to 2 VREF

     Differential/single-ended

     Limit registers per channel

  2 high-side current sense

     48 V max operation

     ±1% FS accuracy

     ±200 mV input range

  3-channel temperature sensor

     Diode temperature measurement

     ±2°C accuracy

     Measurement range: −10°C to +90°C

  Internal 2.5 V reference

  I2C®-compatible serial interface

  Temperature range: −40°C to +105°C

  Alert function

  Package type: LFCSP-56, TQFP-64

APPLICATIONS

  Cellular base station (GSM, EDGE, UMTS, CDMA)

  Point-to-multipoint and other RF transmission systems

  12 V, 24 V, 48 V automotive applications

  Industrial control