Analog Devices’ Level-translating ADC Driver Simplifies Signal Conditioning For High-voltage Industrial And Instrumentation Designs

By translating ±10-V signals to 0‑to-4-V input levels, the 15-MHz AD8275 is especially suited for driving higher-speed 16-bit successive approximation (SAR) converters, including ADI’s AD7685 SAR ADC. The new amplifier can be configured for differential outputs to drive differential input converters, such as the AD7688 PulSAR® ADC, and can be used to drive lower sample-rate 18-bit converters, including ADI’s AD7678 PulSAR ADC.

The AD8275 G = 0.2 difference amplifier includes internal, matched, precision laser-trimmed resistors that achieve 0.002 percent gain error, and 1 ppm/°C (maximum) gain drift. Delivering low distortion and a fast 450-ns settling time to 0.001%, the amplifier is ideal for system engineers designing applications where quick, accurate data capture is required. In addition to eliminating high-voltage power supplies, discrete resistor dividers, driver amplifiers, and other signal conditioning circuitry previously required to drive SAR ADCs, the AD8275 saves space by virtue of its small footprint 8-lead, 3-mm × 5-mm MSOP (mini small-outline package).

The AD8275 features a wide input voltage range of +40 V to –35 V and rail-to-rail outputs, making an easy to use building block. Single-supply operation reduces the power consumption of the amplifier and helps to protect the ADC from overdrive conditions. The AD8275 can be used as an analogue front end, or it can follow buffers to level translate high voltages to a voltage range accepted by the ADC.