AD7821 Analog Devices, AD7821 Datasheet
AD7821
Specifications of AD7821
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AD7821 Summary of contents
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... WR or RD. The provision allows the part to operate from ± supplies and to digitize bipolar input signals. Alternatively, for unipolar inputs, the V can be grounded and the AD7821 will operate from a single +5 V supply, like the AD7820. The AD7821 has a built-in track-and-hold function capable of digitizing full-scale signals up to 100 kHz max ...
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... AD7821–SPECIFICATIONS V (–) = –2.5 V. These test conditions apply unless otherwise stated. All specifications T REF apply for RD Mode (Pin V). Parameter K Version UNIPOLAR INPUT RANGE 2 Resolution 8 ± Total Unadjusted Error Minimum Resolution for which No Missing Codes are Guaranteed 8 BIPOLAR INPUT RANGE ...
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... FALL 1 Model AD7821KN –40°C to +85°C AD7821KP AD7821KR –40°C to +85°C AD7821BQ –40°C to +85°C AD7821TQ –55°C to +125°C ± 1 max b. High AD7821TE NOTES 1 To order MIL-STD-883, Class B processed parts, add /883B to part number. Contact local sales office for military data sheet. ...
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... ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD7821 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality ...
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... TERMINOLOGY LEAST SIGNIFICANT BIT (LSB) An ADC with 8-bit resolution can resolve one part full scale). For the AD7821 operating in either the unipolar or bipolar input range with 5 V full scale, one LSB is 19.53 mV. TOTAL UNADJUSTED ERROR This is a comprehensive specification which includes relative accuracy, offset error, and full-scale error ...
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... Performance Characteristics AD7821 TPC 1. Conversion Time (RD Mode) vs.Temperature TPC 4. Accuracy vs TPC 7. Effective Number of Bits vs. Input Signal ( ± 2.5 V) Frequency TPC 2. Power Supply Current vs. Temperature (Not Including Reference Ladder) TPC 5. Accuracy vs TPC Internal Time Delay vs. INTL Temperature –6– ...
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... The analog input of the AD7821 behaves somewhat differently than conventional ADCs. This is due to the ADC’s sampled data comparators, which take varying amounts of input current depending on the cycle of the converter. The equivalent input circuit of the AD7821 is shown in Figure 6. When a conversion ends (e.g., falling edge of INT, WR-RD (−) ...
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... V will not normally degrade the ADC’s perfor- IN mance. In effect, the AD7821 does not “look” at the input when these transients occur. The comparators’ inputs track V not sampled until the falling edge of WR (WR-RD Mode (RD Mode least 350 ns (t ...
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... The AD7821 has two basic interface modes which are determined by the status of the MODE pin. When this pin is low, the converter is in the RD mode, with this pin high, the AD7821 is set up for the WR-RD mode. The RD mode is designed for microprocessors that can be driven into a WAIT state ...
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... CS and RD low (READ operation). Both CS and RD are then kept low until output data appears. Figure 11. RD Mode In this mode, Pin 6 of the AD7821 is configured as a status out- put, RDY. This RDY output can be used to drive the processor READY or WAIT input open-drain output (no inter- nal-pull-up device) which goes low after the falling edge of CS and goes high impedance at the end of conversion ...
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... Dn is the data register into which the result is placed. Figure 14. AD7821 to 68008 Interface AD7821 – 8088 INTERFACE A typical interface to the 8088 is shown in Figure 15. The AD7821 is configured for the RD interface mode. One read instruction starts a conversion and reads the result. The read cycle is stretched out over the entire conversion period by taking the RDY line back to the READY input of the 8088 ...
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... AD7821 APPLYING THE AD7821 The AD7821 is specified for a unipolar input range and a bipolar input range of –2 +2.5 V. The V V (+) voltages required for these input ranges are outlined REF below. See the Typical Performance Characteristics section for operation with unspecified input voltage ranges. ...
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... However, the internal logic delay and, therefore, the sampling instant can vary from device to device, but is typically within ±5 ns. This means that a maximum common input sine wave of ± 2 kHz, applied to any number of AD7821s in the circuit of Figure 22, will yield a maximum difference between the converter outputs of typically ± 1/4 LSB. ...
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... AD7821 20-Lead Plastic Dual-in-Line Package [PDIP] (N-20) Dimensions shown in inches and (millimeters) 0.985 (25.02) 0.965 (24.51) 0.295 (7.49) 0.945 (24.00) 0.285 (7.24) 0.275 (6.99 0.180 (4.57) 0.015 (0.38) MIN MAX 0.150 (3.81) 0.130 (3.30) SEATING 0.100 0.060 (1.52) 0.110 (2.79) 0.022 (0.56) PLANE (2.54) 0.050 (1.27) 0.018 (0.46) BSC 0.045 (1.14) 0.014 (0.36) COMPLIANT TO JEDEC STANDARDS MO-095-AE CONTROLLING DIMENSIONS ARE IN INCHES ...
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... SQ 0.120 (3.04) 0.395 (10.02) 0.090 (2.29) SQ 0.385 (9.78) COMPLIANT TO JEDEC STANDARDS MO-047AA CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN –15– AD7821 0.020 (0.50) R 0.330 (8.38) BOTTOM VIEW 0.290 (7.37) (PINS UP) Page ...
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