Description

The AD7225 contains four 8-bit voltage output digital-to-analog converters, with output buffer amplifiers and interface logic on a single monolithic chip. Each D/A converter has a separate reference input terminal. No external trims are required to achieve full specified performance for the part.The double-buffered interface logic consists of two 8-bit registers per channel -an input register and a DAC register. Control inputs A0 and A1 determine which input register is loaded when WR goes low. Only the data held in the DAC registers determines the analog outputs of the converters. The double-buffering allows simultaneous update of all four outputs under control of LDAC. All logic inputs are TTL and CMOS (5V) level compatible and the control logic is speed compatible with most 8-bit microprocessors.Specified performance is guaranteed for input reference voltages from +2V to +12.5V when using dual supplies. The part is also specified for single supply operation using a reference of +10V. Each output buffer amplifier is capable of developing +10V across a 2 K(Ω) load.The AD7225 is fabricated on an all ion-implanted high speed Linear Compatible CMOS (LC2MOS) process which has been specifically developed to integrate high-speed digital logic circuits and precision analog circuitry on the same chip.PRODUCT HIGHLIGHTS DACs and Amplifiers on CMOS Chip. The single-chip design of four 8-bit DACs and amplifiers allows a dramatic reduction in board space requirements and offers increased reliability in systems using multiple converters. Its pinout is aimed at optimizing board layout with all analog inputs and outputs at one end of the package and all digital inputs at the other. Single- or Dual-Supply Operation. The voltage-mode configuration of the AD7225 allows single-supply operation. The part can also be operated with dual supplies, giving enhanced performance for some parameters. Versatile Interface Logic. The AD7225 has a common 8-bit data bus with individual DAC latches, providing a versatile control architecture for simple interface to microprocessors. The double-buffered interface allows simultaneous update of the four outputs. Separate Reference Input for Each DAC. The AD7225 offers great flexibility in dealing with input signals, with a separate reference input provided for each DAC and each reference having variable input voltage capability.