a FEATURES Complete 12-Bit D/A Function Double-Buffered Latch On Chip Output Amplifier High Stability Buried Zener Reference Single Chip Construction Monotonicity Guaranteed Over Temperature Linearity Guaranteed Over Temperature: 1/2 LSB max Settling Time: 3 s max to 0.01% Guaranteed for Operation with ؎12 V or ؎15 V Supplies Low Power: 300 mW Including Reference TTL/5 V CMOS Compatible Logic Inputs Low Logic Input Currents MIL-STD-883 Compliant Versions Available PRODUCT DESCRIPTION
The AD667 is a complete voltage output 12-bit digital-to-analog converter including a high stability buried Zener voltage reference and double-buffered input latch on a single chip. The converter uses 12 precision high speed bipolar current steering switches and a laser trimmed thin-film resistor network to provide fast settling time and high accuracy. Microprocessor compatibility is achieved by the on-chip doublebuffered latch. The design of the input latch allows direct interface to 4-, 8-, 12-, or 16-bit buses. The 12 bits of data from the first rank of latches can then be transferred to the second rank, avoiding generation of spurious analog output values. The latch responds to strobe pulses as short as 100 ns, allowing use with the fastest available microprocessors. The functional completeness and high performance in the AD667 results from a combination of advanced switch design, high speed bipolar manufacturing process, and the proven laser wafer-trimming (LWT) technology. The AD667 is trimmed at the wafer level and is specified to ± 1/4 LSB maximum linearity error (K, B grades) at +25°C and ± 1/2 LSB over the full operating temperature range. The subsurface (buried) Zener diode on the chip provides a low noise voltage reference which has long-term stability and temperature drift characteristics comparable to the best discrete reference diodes. The laser trimming process which provides the excellent linearity, is also used to trim the absolute value of the reference as well as its temperature coefficient. The AD667 is thus well suited for wide temperature range performance with ± 1/2 LSB maximum linearity error and guaranteed monotonicity over the full temperature range. Typical full-scale gain TC is 5 ppm/°C.
Microprocessor-Compatible 12-Bit D/A Converter AD667* FUNCTIONAL BLOCK DIAGRAM
The AD667 is available in five performance grades. The AD667J and K are specified for use over the 0°C to +70°C temperature range and are available in a 28-pin molded plastic DIP (N) or PLCC (P) package. The AD667S grade is specified for the –55°C to +125°C range and is available in the ceramic DIP (D) or LCC (E) package. The AD667A and B are specified for use over the –25°C to +85°C temperature range and are available in a 28-pin hermetically sealed ceramic DIP (D) package. PRODUCT HIGHLIGHTS
1. The AD667 is a complete voltage output DAC with voltage reference and digital latches on a single IC chip. 2. The double-buffered latch structure permits direct interface to 4-, 8-, 12-, or 16-bit data buses. All logic inputs are TTL or 5 volt CMOS compatible. 3. The internal buried Zener reference is laser-trimmed to 10.00 volts with a ± 1% maximum error. The reference voltage is also available for external application. 4. The gain setting and bipolar offset resistors are matched to the internal ladder network to guarantee a low gain temperature coefficient and are laser-trimmed for minimum full-scale and bipolar offset errors. 5. The precision high speed current steering switch and on-board high speed output amplifier settle within 1/2 LSB for a 10 V full-scale transition in 2.0 µs as when properly compensated. 6. The AD667 is available in versions compliant with MILSTD-883. Refer to the Analog Devices Military Products Databook or current AD667/883B data sheet for detailed specifications.
- Protected by Patent Numbers 3,803,590; 3,890,611; 3,932,863; 3,978,473; 4,020,486; and others pending.
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