Low Cost Signal a Conditioning 8-Bit ADC AD670 FUNCTIONAL BLOCK DIAGRAM FEATURES Complete 8-Bit Signal Conditioning A/D Converter Including Instrumentation Amp and Reference Microprocessor Bus Interface 10 ms Conversion Speed Flexible Input Stage: Instrumentation Amp Front End Provides Differential Inputs and High Common-Mode Rejection No User Trims Required No Missing Codes Over Temperature Single +5 V Supply Operation Convenient Input Ranges 20-Pin DIP or Surface-Mount Package Low Cost Monolithic Construction MIL-STD-883B Compliant Versions Available GENERAL DESCRIPTION The S grade is also available with optional processing to The AD670 is a complete 8-bit signal conditioning analog- MIL-STD-883 in 20-pin ceramic DIP or 20-terminal LCC to-digital converter. It consists of an instrumentation amplifier packages. The Analog Devices Military Products Databook front end along with a DAC, comparator, successive approxima- should be consulted for detailed specifications. tion register (SAR), precision voltage reference, and a three- state output buffer on a single monolithic chip. No external PRODUCT HIGHLIGHTS components or user trims are required to interface, with full 1. The AD670 is a complete 8-bit A/D including three-state accuracy, an analog system to an 8-bit data bus. The AD670 outputs and microprocessor control for direct connection to will operate on the +5 V system supply. The input stage pro- 8-bit data buses. No external components are required to vides differential inputs with excellent common-mode rejection perform a conversion. and allows direct interface to a variety of transducers. 2. The flexible input stage features a differential instrumenta- The device is configured with input scaling resistors to permit tion amp input with excellent common-mode rejection. This two input ranges: 0 mV to 255 mV (1 mV/LSB) and 0 to 2.55 V allows direct interface to a variety of transducers without (10 mV/LSB). The AD670 can be configured for both unipolar preamplification. and bipolar inputs over these ranges. The differential inputs and 3. No user trims are required for 8-bit accurate performance. common-mode rejection of this front end are useful in applica- 4. Operation from a single +5 V supply allows the AD670 to tions such as conversion of transducer signals superimposed on run off of the microprocessors supply. common-mode voltages. 5. Four convenient input ranges (two unipolar and two bipolar) The AD670 incorporates advanced circuit design and proven are available through internal scaling resistors: 0 mV to processing technology. The successive approximation function 2 255 mV (1 mV/LSB) and 0 V to 2.55 V (10 mV/LSB). is implemented with I L (integrated injection logic). Thin-film SiCr resistors provide the stability required to prevent missing 6. Software control of the output mode is provided. The user codes over the entire operating temperature range while laser can easily select unipolar or bipolar inputs and binary or 2s wafer trimming of the resistor ladder permits calibration of the complement output codes. device to within 1 LSB. Thus, no user trims for gain or offset are required. Conversion time of the device is 10 s. The AD670 is available in four package types and five grades. The J and K grades are specified over 0C to +70C and come in 20-pin plastic DIP packages or 20-terminal PLCC packages. The A and B grades (40C to +85C) and the S grade (55C to +125C) come in 20-pin ceramic DIP packages. REV. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Tel: 617/329-4700 Fax: 617/326-8703AD670SPECIFICATIONS ( V = +5 V and +258C, unless otherwise noted) CC Model AD670J AD670K Min Typ Max Min Typ Max Units OPERATING TEMPERATURE RANGE 0 +70 0 +70 C RESOLUTION 8 8 Bit CONVERSION TIME 10 10 s RELATIVE ACCURACY 61/2 61/4 LSB T to T 6l/2 61/2 LSB MIN MAX 1 DIFFERENTIAL LINEARITY ERROR T to T GUARANTEED NO MISSING CODES ALL GRADES MIN MAX GAIN ACCURACY +25C 61.5 60.75 LSB T to T 62.0 61.0 LSB MIN MAX UNIPOLAR ZERO ERROR +25C 61.5 60.75 LSB T to T 62.0 61.0 LSB MIN MAX BIPOLAR ZERO ERROR +25C 61.5 60.75 LSB T to T 62.0 61.0 LSB MIN MAX ANALOG INPUT RANGES DIFFERENTIAL (V to +V ) IN IN Low Range 0 to +255 0 to +255 mV 128 to +127 128 to +127 mV High Range 0 to +2.55 0 to +2.55 V 1.28 to +1.27 1.28 to +1.27 V ABSOLUTE (Inputs to Power GND) Low Range T to T 0.150 V 3.4 0.150 V 3.4 V MIN MAX CC CC High Range T to T 1.50 V 1.50 V V MIN MAX CC CC BIAS CURRENT (255 mV RANGE) T to T 200 500 200 500 nA MIN MAX OFFSET CURRENT (255 mV RANGE) T to T 40 200 40 200 nA MIN MAX 2.55 V RANGE INPUT RESISTANCE 8.0 12.0 8.0 12.0 k 2.55 V RANGE FULL-SCALE MATCH + AND INPUT 1/2 1/2 LSB COMMON-MODE REJECTION RATIO (255 mV RANGE) 11 LSB COMMON-MODE REJECTION RATIO (2.55 V RANGE) 1 1 LSB POWER SUPPLY Operating Range 4.5 5.5 4.5 5.5 V Current I 30 45 30 45 mA CC Rejection Ratio T to T 0.015 0.015 % of FS/% MIN MAX DIGITAL OUTPUTS SINK CURRENT (V = 0.4 V) OUT T to T 1.6 1.6 mA MIN MAX SOURCE CURRENT (V = 2.4 V) OUT T to T 0.5 0.5 mA MIN MAX THREE-STATE LEAKAGE CURRENT 640 640 A OUTPUT CAPACITANCE 5 5 pF DIGITAL INPUT VOLTAGE V 0.8 0.8 V INL V 2.0 2.0 V INH DIGITAL INPUT CURRENT (0 V +5 V) IN I 100 100 A INL I +100 +100 A INH INPUT CAPACITANCE 10 10 pF NOTES 1 Tested at V = 4 5 V, 5.0 V and 5.5 V. CC Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and max specifications are guaranteed although only those shown in boldface are tested on all production units. Specifications subject to change without notice. 2 REV. A