The AD7870/AD7875/AD7876 are fast， complete， 12-bit analog-to-digital converters （ADCs）。 These converters consist of a track-and-hold amplifier， an 8 μs successive approximation ADC， a 3 V buried Zener reference， and versatile interface logic. The ADCs feature a self-contained internal clock which is laser trimmed to guarantee accurate control of conversion time. No external clock timing components are required; the on-chip clock may be overridden by an external clock if required. The parts offer a choice of three data output formats： a single， parallel， 12-bit word; two 8-bit bytes or serial data. Fast bus access times and standard control inputs ensure easy interfacing to modern microprocessors and digital signal processors. All parts operate from ±5 V power supplies. The AD7870 and AD7876 accept input signal ranges of ±3 V and ±10 V， respectively， while the AD7875 accepts a unipolar 0 V to +5 V input range. The parts can convert full power signals up to 50 kHz. The AD7870/AD7875/AD7876 feature dc accuracy specifications， such as linearity， full-scale and offset error. In addition， the AD7870 and AD7875 are fully specified for dynamic performance parameters including distortion and signal-tonoise ratio.