The AD667 is a complete voltage-output, 12-bit single-chip digital-to-analog converter with a high-stability embedded Zener reference and dual-buffer input latches. The converter features 12 precision, high-speed, bipolar current-guide switches and a laser-tuned thin-film resistor network that provides fast settling times and high-precision features.
Microprocessor compatibility is achieved through dual buffer latches on the chip. The input latch is capable of directly interfacing with 4-, 8-, 12-, or 16-bit buses. Therefore, the 12-bit data of the first level of latch can be transferred to the second level of latch, avoiding stray analog outputs. The latch responds to short strobe pulses of 100 ns, allowing it to work with the fastest microprocessors available.
The AD667's comprehensive features and high performance are the result of an advanced switching design, high-speed bipolar manufacturing process, and proven laser wafer adjustment technology (LWT). The device is adjusted at the wafer stage with a maximum linear error of ±1/4 LSB (class K, B grade) at +25°C and a linear error of ±1/2 LSB over the entire operating temperature range.
The chip's subsurface (embedded) Zener diode provides a low-noise reference source with long-term stability and excellent temperature drift characteristics, outperforming the best discrete voltage reference diodes. The laser adjustment process has excellent linearity and can also be used to adjust the absolute value of the reference voltage source and its temperature coefficient. As a result, the AD667 has a wide temperature range performance with a maximum linear error of ±1/2 LSB and can guarantee monotonicity over the entire temperature range. The typical temperature coefficient of gain in the full scale is 5 ppm/°C.
The AD667 is divided into five levels based on performance. The AD667J and AD667K are rated for a temperature range of 0°C to +70°C and are available in 28-pin injection molded DIP (N) or PLCC (P) packages. The AD667S class is rated for a temperature range of -55°C to +125°C and is available in either ceramic DIP (D) or LCC (E) packages. The AD667A and AD667B are rated for a temperature range of -25°C to +85°C and are available in a 28-pin sealed ceramic DIP (D) package.