AD7846 Analog Devices, AD7846 Datasheet
AD7846
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AD7846 Summary of contents
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... LSBs integral linearity error Microprocessor compatible with readback capability Unipolar or bipolar output Multiplying capability Low power (100 mW typical) GENERAL DESCRIPTION The AD7846 is a 16-bit DAC constructed with the Analog Devices, 2 Inc., LC MOS process. It has V and V REF+ and an on-chip output amplifier. These can be configured to give a unipolar output range ( + bipolar output ranges (± ...
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... Unipolar Binary Operation ........................................................... 13 Bipolar Operation ........................................................................... 14 Multiplying Operation ............................................................... 14 Position Measurement Application .............................................. 15 Microprocessor Interfacing ........................................................... 16 AD7846-to-8086 Interface ........................................................ 16 AD7846-to-MC68000 Interface ............................................... 16 Digital Feedthrough ....................................................................... 17 Application Hints ........................................................................... 18 Noise ............................................................................................ 18 Grounding ................................................................................... 18 Printed Circuit Board Layout ................................................... 18 Outline Dimensions ....................................................................... 20 ...
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... V to +10 V REF− OUT 1 LSB = 305 μV All grades guaranteed monotonic V load = 10 MΩ OUT V load = 10 MΩ OUT Resistance from REF+ REF− Typically 30 kΩ any power supply AD7846 = +5 V; REF+ ...
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... Temperature ranges as follows versions: 0°C to +70° versions: −40°C to +85°C. 2 Guaranteed by design and characterization, not production tested. 3 The AD7846 is functional with power supplies of ±12 V. See the Typical Performance Characteristics section. 4 Sensitivity of gain error, offset error, and bipolar zero error PERFORMANCE CHARACTERISTICS These characteristics are included for design guidance and are not subject to test − ...
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... DATA VALID DBn 10pF 3kΩ DGND Figure 5. Load Circuit for Access Time (t )—High 3kΩ DBn 10pF DGND Figure 6. Load Circuits for Bus Relinquish Time (t AD7846 OH )—High ...
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... AD7846 ABSOLUTE MAXIMUM RATINGS Table 4. Parameter Rating V to DGND −0 + DGND −0 (whichever is lower DGND +0 − DGND REF DGND REF− DGND OUT DD (whichever is lower DGND ...
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... AD7846 REF REF– TOP VIEW (Not to Scale DB15 DGND 10 20 DB6 DB14 Figure 8. CERDIP Pin Configuration V R REF− OUT − OUT − AD7846 ...
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... AD7846 TYPICAL PERFORMANCE CHARACTERISTICS A1 –0.40V 1V 2mV 20µs Figure 9. AC Feedthrough rms, 10 kHz Sine Wave REF +15V –15V +1V rms REF + REF – 100 1k 10k FREQUENCY (Hz) Figure 10. AC Feedthrough to V OUT +15V –15V ...
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... Figure 17. Spectral Response of Digitally Constructed Sine Wave 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 11 Figure 18. Typical Integral Nonlinearity vs. V 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0 Figure 19. Typical Differential Nonlinearity vs. V 1.70V ST 422 SEC Rev Page AD7846 T = +25° +5V REF REF– GAIN = + ( +25°C A ...
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... REF− current and the DAC leakage current. Bipolar Zero Error When the AD7846 is connected for bipolar output and 10…000 is loaded to the DAC, the deviation of the analog output from the ideal midscale called the bipolar zero error. Digital-to-Analog Glitch Impulse This is the amount of charge injected from the digital inputs to the analog output when the inputs change state ...
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... CIRCUIT DESCRIPTION DIGITAL SECTION Figure 20 shows the digital control logic and on-chip data latches in the AD7846. Table 7 is the associated truth table. The digital- to-analog converter (DAC) has two latches that are controlled by four signals LDAC , and CLR . The input latch is connected to the data bus (DB15 to DB0) ...
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... V REF– OUTPUT STAGE The output stage of the AD7846 is shown in Figure 22 capable of driving a 2 kΩ/1000 pF load. It also has a resistor feedback network that allows the user to configure it for gains Table 6 shows the different output ranges that are possible. ...
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... UNIPOLAR BINARY OPERATION Figure 23 shows the AD7846 in the unipolar binary circuit configuration. The DAC is driven by the AD586 Because R is tied the output amplifier has a gain and the output range + range is required, R should be tied to V ...
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... AD7846 BIPOLAR OPERATION Figure 24 shows the AD7846 set up for ±10 V bipolar operation. The AD588 provides precision ±5 V tracking outputs that are fed to the V and V inputs of the AD7846. The code table REF+ REF− for Figure 24 is shown in Table 9. +15V +15V R1 39kΩ ...
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... POSITION MEASUREMENT APPLICATION Figure 25 shows the AD7846 in a position measurement applica- tion using an linear variable displacement transducer (LVDT), an AD630 synchronous demodulator and a comparator to make a 16-bit LVDT-to-digital converter. The LVDT is excited with a fixed frequency and fixed amplitude sine wave (usually 2.5 kHz p-p) ...
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... MICROPROCESSOR INTERFACING AD7846-TO-8086 INTERFACE Figure 26 shows the 8086 16-bit processor interfacing to the AD7846. The double buffering feature of the DAC is not used in this circuit because LDAC is permanently tied AD0 to AD15 (the 16-bit data bus) are connected to the DAC data bus (DB0 to DB15) ...
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... To minimize this digital feedthrough, isolate PROCESSOR *LINEAR CIRCUITRY OMITTED FOR CLARITY Figure 29. AD7846 Interface Circuit Using Latches to Minimize Digital Feedthrough the DAC from the noise source. Figure 29 shows an interface circuit that isolates the DAC from the bus. Note that to make use of the AD7846 readback feature using the isolation technique of Figure 29, the latch needs to be bidirectional ...
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... R5 appears as part of the load and therefore introduces no errors. PRINTED CIRCUIT BOARD LAYOUT Figure 31 shows the AD7846 in a typical application with the AD588 reference, producing an output analog voltage in the ±10 V range. Full-scale and bipolar zero adjustment are provided by Potentiometer R2 and Potentiometer R3. Latches (2 × ...
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... DB4 27 10µF 6 DB3 DB2 1 9 DB1 DGND DB0 R CLR 24 5 OUT LDAC 25 Figure 31. Schematic for AD7846 Board Rev Page AD7846 J1 +5V C31/A31 C7 0.1µ C4/A4 17 C5/A5 16 C6/A6 15 74LS245 C7/A7 14 C8/A8 13 C9/A9 12 C10/A10 11 C11/A11 C12/A12 17 C13/A13 ...
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... AD7846 OUTLINE DIMENSIONS PIN 1 0.225(5.72) MAX 0.200 (5.08) 0.125 (3.18) 0.026 (0.66) 0.014 (0.36 0.250 (6.35) MAX 0.200 (5.08) 0.115 (2.92) 0.022 (0.56) 0.014 (0.36) 0.100 (2.54) 0.005 (0.13) MAX MIN 28 15 0.610 (15.49) 0.500 (12.70 0.015 (0.38) 1.490 (37.85) MAX MIN 0.150 (3.81) MIN 0.100 SEATING 0.070 (1.78) (2.54) PLANE 0.030 (0.76) BSC 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 ...
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... Dimensions shown in inches and (millimeters) Rev Page 0.300 (7.62) REF 0.075 0.020 (0.51) (1.91) MIN REF 0.028 (0.71 0.022 (0.56) 0.05 (1.27) BOTTON 28 VIEW 1 0.15 (3.81) REF 0.075 (1.91) REF 0.095 (2.41) 0.055 (1.40) 0.075 (1.90) 0.045 (1.14) (E-28-1) 0.180 (4.57) 0.165 (4.19) 0.020 (0.51) MIN 0.021 (0.53) 0.013 (0.33) BOTTOM 0.430 (10.92) 0.390 (9.91) (PINS UP) 0.032 (0.81) 0.026 (0.66) 0.045 (1.14) R 0.025 (0.64) (P-28) AD7846 VIEW ...
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... AD7846KP 0°C to +70°C AD7846KP-REEL 0°C to +70°C AD7846KPZ 0°C to +70°C AD7846KPZ-REEL 0°C to +70°C AD7846AP −40°C to +85°C AD7846APZ −40°C to +85°C AD7846AQ −40°C to +85°C AD7846BP −40°C to +85°C AD7846BPZ −40°C to +85°C AD7846ACHIPS − ...
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... NOTES Rev Page AD7846 ...
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... AD7846 NOTES ©2000–2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D08490-0-4/10(G) Rev Page ...