The AD766 is a 16-bit DSP DACPORT with a three-wire interface that interfaces directly with popular DSP processors such as the ADSP-2101, TMS320CXX, and DSP56001 serial ports without the need for additional adhesive logic. In addition, the AD766 is fully configured and provides on-chip serial-to-parallel input format conversion, a 16-bit current-guided DAC, a voltage reference, and a voltage output operational amplifier. Manufactured using Analog Devices' BiMOS II mixed-signal process, the AD766 offers bipolar transistors, MOS transistors, and thin-film resistors for precision analog circuits in addition to CMOS logic devices.
The AD766 is designed and layoutd for AC performance and has been tested to guarantee signal-to-noise ratios of 94 dB (20 kHz) and 79 dB (250 kHz). The silicon-chromium thin film resistors are laser-tuned to reduce total harmonic distortion to less than -81 dB (1 kHz), a property that has also been tested for production. Optional linear adjustment pins eliminate intermediate level differential linear errors, resulting in lower total harmonic distortion for small signals.
The AD766's output amplifier provides a ±3 V signal with high voltage slew rate, small burrs, and fast settling. The output amplifier has short-circuit protection and can withstand infinite short-circuit voltages to the ground.
The serial interface consists of a bit clock input, a data input, and a latch enable input. The binary complement data word is fed into a serial parallel converter along the falling clock in an MSB-first manner, which is consistent with the serial protocol of commonly used DSP processors. The input clock can support data transfer up to 12.5 MHz. At the drop edge of latch enablement, the 16-bit data recently read into the serial input register updates the internal DAC input register at the sample rate.
The AD766 operates from a ±5 V to ±12 V supply. The digital power supply + VL and -VL can be separated from the analog signal power supply + VS and -VS to reduce digital crosstalk. Separate analog and digital ground pins are also available. An internal bandgap reference provides the output amplifier with a precision voltage source that does not change with temperature and time.
Typical power consumption is 120 mW when powered from a ±5 V supply; Typical power consumption is 300 mW when powered from a ± 12 V supply. The AD766 offers three grades: commercial (0°C to +70°C), industrial (-40°C to +85°C) and military (-55°C to +125°C). Commercial and industrial grade devices are available in a 16-pin molded DIP package; The military-grade devices meet MIL-STD-883B manufacturing standards and are available in a 16-pin ceramic DIP package. For the features of the military version, refer to Analog Devices' Military Product Data Sheet or the current military data sheet.