AD420是一款完整的数字电流环路输出转换器，专为满足工业控制市场的需求而设计。它提供一种高精度、全集成、低成本的单芯片解决方案，用于产生电流环路信号，采用紧凑型24引脚SOIC或PDIP封装。
The output current range can be programmed to be 4 mA-20 mA, 0 mA-20 mA, or 0 mA-24 mA for over-range. Alternatively, the AD420 can provide voltage output from a single pin that needs to be configured with an external single buffer amplifier for 0 V-5 V, 0 V-10 V, ±5 V, or ± 10 V output.
The 3.3 Mbaud serial input logic design minimizes galvanic isolation costs and can be easily connected to commonly used microprocessors. It can be used in three-wire mode or asynchronous mode and provides a serial output pin to daisy-chain multiple DACs on one side of the isolation current loop.
The AD420 uses sigma-delta (SD) DAC technology to achieve 16-bit monotonicity at a very low cost. Full scale 0.1% establishment time does not exceed 3 ms. The external components require only 3 low-cost capacitors (except for the standard transient protection circuitry) for use in the DAC output filter.
If the AD420 is to be used in extreme temperatures and supply voltages, an external output transistor can be utilized to minimize power consumption on the chip via the "BOOST" pin.
When an open circuit appears in the loop, the FAULT DETECT pin generates a signal. The on-chip reference source can be used to deliver precision +5 V to external components outside of the AD420; If the user requires temperature stability above 25 ppm/°C, an external precision reference source such as the AD586 can also be used as a reference.
The AD420 is available in 24-pin SOIC and PDIP packages and has an operating temperature range of -40°C to +85°C industrial temperatures.
The AD420 datasheet (Rev F, 10/99) is now available with some information on new applications.