Dual 8-Bit, CMOS, Voltage Output, D/A Converter in a Single Chip

The DAC-8228 is a dual 8-bit, voltage output, CMOS, D/A converter in a single chip. It was designed to drop into AD7528 / AD7628 sockets eliminating two external op amps in applications such as hard disk drives. These applications generally operate the AD7528 / AD7628 with zero volts applied to VREF and offset AGND to +2.5 or +5 volts. The DAC-8228 is tested under both these conditions.

The DAC-8228 can also be used in those applications requiring a unipolar output voltage. It can deliver an output voltage between 0V and +10V with VDD = +14V (maximum output voltage is VDD -4V). The DAC-8228's reference input can accept a negative voltage from 0V to -10V (the DAC's internal unity-gain inverting amplifier inverts the input signal). Choose the DAC-8229 for bipolar operation.

The DAC8228 offers CerDIP and plastic packaged devices in the extended industrial temperature range of -40° to +85°C. Applications requiring the military temperature range should use the DAC-8229. To make the DAC-8229 pin and functionally compatible with the DAC-8228, AGND A and AGND B should be tied together to function as VZ, and VSS connected to GND.

The DAC-8228 consists of two CMOS voltage output amplifiers, two high-accuracy R-2R resistor ladder networks, interface control logic, and two 8-bit registers. An internal regulator maintains TTL logic compatibility and fast microprocessor interface timing over the full VDD range.

The DAC-8228 dissipates only 90mW in the space saving 20-pin 0.3" DIP or the 20-lead SO surface mount package. Its compact size, low power, and economical cost per channel, makes it attractive for applications requiring multiple D/A converters without sacrificing circuit-board space. Reduced parts count also improves system reliability.

Using PMI's advanced oxide-isolated, silicon-gate CMOS process, coupled with its highly-stable thin-film resistor ladder, allows the DAC-8228 to offer superior matching and temperature tracking between DACs.

APPLICATIONS

* Disk Drive Systems

* Automatic Test Equipment

* Process/Industrial Controls

* Energy Controls

* Programmable Instrumentation

* Multi-Channel Microprocessor-Controlled Systems

* Servo Control Systems

* Two 8-Bit Voltage Out DACs in a Single Chip

* Fits 7528/7628 Sockets

* Adjustment Free Internal CMOS Ops Amps

* Single +12V to +15V Operation

* TTL Compatible Over Full VDD range

* Fast Interface Timing ..............TWR = 50 ns