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ADC0801 Datasheet

Download or read online National Semiconductor ADC0801 8-Bit Microprocessor Compatible A/D Converters pdf datasheet.
Also see for ADC0801: Datasheet #1 (36 pages)



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ADC0801/ADC0802/ADC0803/ADC0804/ADC0805
8-Bit µP Compatible A/D Converters
General Description
The ADC0801, ADC0802, ADC0803, ADC0804 and
ADC0805 are CMOS 8-bit successive approximation A/D
converters
that
use
a
differential
ladder — similar to the 256R products. These converters are
designed to allow operation with the NSC800 and INS8080A
derivative control bus with TRI-STATE
®
rectly driving the data bus. These A/Ds appear like memory
locations or I/O ports to the microprocessor and no interfac-
ing logic is needed.
Differential analog voltage inputs allow increasing the
common-mode rejection and offsetting the analog zero input
voltage value. In addition, the voltage reference input can be
adjusted to allow encoding any smaller analog voltage span
to the full 8 bits of resolution.
Features
n Compatible with 8080 µP derivatives — no interfacing
logic needed - access time - 135 ns
n Easy interface to all microprocessors, or operates “stand
alone”
Connection Diagram
Dual-In-Line and Small Outline (SO) Packages
Ordering Information
TEMP RANGE
±
Bit Adjusted
1
4
±
ERROR
1
Bit Unadjusted
2
±
1
Bit Adjusted
2
±
1Bit Unadjusted
PACKAGE OUTLINE
TRI-STATE
®
is a registered trademark of National Semiconductor Corp.
Z-80
®
is a registered trademark of Zilog Corp.
© 1999 National Semiconductor Corporation
DS005671
n Differential analog voltage inputs
n Logic inputs and outputs meet both MOS and TTL
voltage level specifications
n Works with 2.5V (LM336) voltage reference
potentiometric
n On-chip clock generator
n 0V to 5V analog input voltage range with single 5V
supply
output latches di-
n No zero adjust required
n 0.3" standard width 20-pin DIP package
n 20-pin molded chip carrier or small outline package
n Operates ratiometrically or with 5 V
analog span adjusted voltage reference
Key Specifications
n Resolution
n Total error
n Conversion time
ADC080X
DS005671-30
See Ordering Information
0˚C TO 70˚C
0˚C TO 70˚C
ADC0802LCWM
ADC0804LCWM
ADC0804LCN
M20B — Small
Outline
November 1999
, 2.5 V
, or
DC
DC
8 bits
±
±
±
1
LSB,
1
LSB and
1 LSB
4
2
100 µs
−40˚C TO +85˚C
ADC0801LCN
ADC0802LCN
ADC0803LCN
ADC0805LCN/ADC0804LCJ
N20A — Molded DIP
www.national.com

Summary of Contents

Page 1

... ADC0801/ADC0802/ADC0803/ADC0804/ADC0805 8-Bit µP Compatible A/D Converters General Description The ADC0801, ADC0802, ADC0803, ADC0804 and ADC0805 are CMOS 8-bit successive approximation A/D converters that use a differential ladder similar to the 256R products. These converters are designed to allow operation with the NSC800 and INS8080A derivative control bus with TRI-STATE ® ...

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... Typical Applications Part Number Adjusted ± ADC0801 ADC0802 ± ADC0803 ADC0804 ADC0805 www.national.com 8080 Interface DS005671-31 Error Specification (Includes Full-Scale, Zero Error, and Non-Linearity 2.500 Connection Full REF DC REF Scale (No Adjustments) (No Adjustments) LSB 1 4 ± 1 LSB 2 1 ...

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... Vapor Phase (60 seconds) Electrical Characteristics 5 V The following specifications apply for V CC Parameter ADC0801: Total Adjusted Error (Note 8) ADC0802: Total Unadjusted Error (Note 8) ADC0803: Total Adjusted Error (Note 8) ADC0804: Total Unadjusted Error (Note 8) ADC0805: Total Unadjusted Error (Note Input Resistance (Pin 9) ...

Page 4

... I Supply Current (Includes CC Ladder Current) ADC0801/02/03/04LCJ/05 ADC0804LCN/LCWM Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating the device beyond its specified operating conditions. Note 2: All voltages are measured with respect to Gnd, unless otherwise specified. The separate A Gnd point should always be wired to the D Gnd. ...

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... Supply Voltage DS005671-38 f vs. Clock Capacitor CLK DS005671-41 Output Current vs Temperature DS005671-44 (Continued) to ground. In all versions of the ADC0801, ADC0802, ADC0803, and CC resistor. Delay From Falling Edge Output Data Valid vs. Load Capacitance DS005671-39 Full-Scale Error vs Conversion Time DS005671-42 Power Supply Current ...

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TRI-STATE Test Circuits and Waveforms t 1H DS005671- DS005671-49 Timing Diagrams (All timing is measured from the 50% voltage points) www.national.com DS005671- ...

Page 7

Timing Diagrams (All timing is measured from the 50% voltage points) (Continued) Note: Read strobe must occur 8 clock periods (8/f ) after assertion of interrupt to guarantee reset of INTR . CLK Typical Applications 6800 Interface Output Enable and ...

Page 8

Typical Applications (Continued) Absolute with a 2.500V Reference For low power, see also LM3852.5 Zero-Shift and Span Adjust: 2V www.national.com Absolute with a 5V Reference DS005671- Span Adjust DS005671-57 8 DS005671- DS005671-58 ...

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Typical Applications (Continued) Directly Converting a Low-Level Signal /2 256 mV V REF 1 mV Resolution with µP Controlled Range /2 128 mV V REF 1 LSB 256 mV) DAC IN DAC ...

Page 10

Typical Applications (Continued) Self-Clocking Multiple A/Ds Use a large R value to reduce loading at CLK R output. www.national.com Digitizing a Current Flow 100 kHz f DS005671-63 10 DS005671-62 External Clocking DS005671-64 1460 kHz CLK ...

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Typical Applications (Continued) Self-Clocking in Free-Running Mode DS005671-65 After power-up, a momentary grounding of the WR input is needed to guarantee operation. Operating with Automotive Ratiometric Transducers (− 85% of ...

Page 12

Typical Applications (Continued) ± Handling 10V Analog Inputs Beckman Instruments # 694-3-R10K resistor array µP Interfaced Temperature-to-Digital Converter Circuit values shown are for 0C T 128˚ Can calibrate each sensor to allow easy replacement, then A/D can ...

Page 13

Typical Applications (Continued) ± Handling 5V Analog Inputs Beckman Instruments # 694-3-R10K resistor array µP Interfaced Comparator with Hysteresis DS005671-35 Read-Only Interface DS005671-33 Protecting the Input Diodes are 1N914 13 DS005671-34 DS005671-9 www.national.com ...

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Typical Applications (Continued) A Low-Cost, 3-Decade Logarithmic Converter LM389 transistors LM324A quad op amp www.national.com Analog Self-Test for a System DS005671-36 14 DS005671-37 ...

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Typical Applications (Continued) Noise Filtering the Analog Input Uses Chebyshev implementation for steeper roll-off unity-gain, 2nd order, low-pass filter Adding a separate filter for each channel increases system response time if an analog multiplexer is ...

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... Note 11: Oversample whenever possible [keep fs Note 12: Consider the amplitude errors which are introduced within the passband of the filter. (Complete shutdown takes 30 seconds.) Use ADC0801, 02 for lowest power consumption. Note: Logic inputs can be driven to V with A/D supply at zero volts. CC Buffer prevents data bus from overdriving output of A/D when in shutdown mode. ...

Page 17

... Functional Description (Continued) Figure 2 shows a worst case error plot for the ADC0801. All center-valued inputs are guaranteed to produce the correct output codes and the adjacent risers are guaranteed to be ± no closer to the center-value points than words apply an analog input equal to the center-value ± ...

Page 18

... Functional Description Transfer Function DS005671-85 FIGURE 3. Clarifying the Error Specs of an A/D Converter 2.0 FUNCTIONAL DESCRIPTION The ADC0801 series contains a circuit equivalent of the 256R network. Analog switches are sequenced by succes- sive approximation logic to match the analog difference input voltage [V () V ()] to a corresponding tap on the R net- ...

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Functional Description (Continued) Note 13: CS shown twice for clarity. Note 14: SAR Successive Approximation Register. After the 1 is clocked through the 8-bit shift register (which completes the SAR search) it appears as the input to the D-type ...

Page 20

Functional Description 2.2 Analog Differential Voltage Inputs and Common-Mode Rejection This A/D has additional applications flexibility due to the ana- log differential voltage input. The V () input (pin 7) can be IN used to automatically subtract a fixed voltage ...

Page 21

Functional Description (Continued) 100 series resistor can be used to isolate this capacitor both the R and C are placed outside the feed- back loop from the output amp, if used. 2.3.4 Noise The leads ...

Page 22

Functional Description DS005671-87 a) Analog Input Signal Example FIGURE 7. Adapting the A/D Analog Input Voltages to Match an Arbitrary Input Signal Range 2.5 Errors and Reference Voltage Adjustments 2.5.1 Zero Error The zero of the A/D does not require ...

Page 23

Functional Description (Continued) DS005671-17 FIGURE 8. Self-Clocking the A/D Heavy capacitive or DC loading of the clock R pin should be avoided as this will disturb normal converter operation. Loads less than 50 pF, such as driving ...

Page 24

Functional Description FIGURE 9. Basic A/D Tester www.national.com For a higher speed test system obtain plotted data, a (Continued) digital-to-analog converter is needed for the test set-up. An accurate 10-bit DAC can serve as the precision voltage source ...

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Functional Description (Continued) FIGURE 10. A/D Tester with Analog Error Output TABLE 1. DECODING THE DIGITAL OUTPUT LEDs HEX BINARY MS GROUP ...

Page 26

... Note 16: Pin numbers for the DP8228 system controller, others are INS8080A. Note 17: Pin 23 of the INS8228 must be tied to 12V through instruction when an interrupt is acknowledged as required by the accompanying sample program. FIGURE 12. ADC0801_INS8080A CPU Interface www.national.com (Continued) resistor to generate the RST 7 26 ...

Page 27

... A7) can be directly used as CS inputs one for each I/O device. 4.1.2 INS8048 Interface The INS8048 interface technique with the ADC0801 series (see Figure simpler than the 8080A CPU interface. There are 24 I/O lines and three test input lines in the 8048. With these extra I/O lines available, one of the I/O lines (bit 0 of port 1) is used as the chip select signal to the A/D, thus eliminating the use of an external address decoder ...

Page 28

Functional Description SAMPLE PROGRAM FOR Figure 13 INS8048 INTERFACE 4.2 Interfacing the Z-80 The Z-80 control bus is slightly different from that of the 8080. General RD and WR strobes are provided and sepa- rate memory request, MREQ, and I/O ...

Page 29

... The following subroutine performs essentially the same func- tion as in the case of the 8080A interface and it can be called from anywhere in the users program. In Figure 16 the ADC0801 series is interfaced to the M6800 microprocessor through (the arbitrarily chosen) Port B of the MC6820 or MC6821 Peripheral Interface Adapter, (PIA). ...

Page 30

... Functional Description SAMPLE PROGRAM FOR Figure 15 ADC0801-MC6800 CPU INTERFACE Note 22: In order for the microprocessor to service subroutines and interrupts, the stack pointer must be dimensioned in the users program. www.national.com (Continued) FIGURE 16. ADC0801MC6820 PIA Interface 30 DS005671-A1 DS005671-25 ...

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... SAMPLE PROGRAM FOR Figure 16 ADC0801MC6820 PIA INTERFACE The following schematic and sample subroutine (DATA IN) may be used to interface (up to) 8 ADC0801s directly to the MC6800 CPU. This scheme can easily be extended to allow the interface of more converters. In this configuration the converters are (arbitrarily) located at HEX address 5000 in the MC6800 memory space ...

Page 32

Functional Description Note 23: Numbers in parentheses refer to MC6800 CPU pin out. Note 24: Numbers of letters in brackets refer to standard M6800 system common bus code. FIGURE 17. Interfacing Multiple A/ MC6800 System www.national.com (Continued) 32 ...

Page 33

... The INS8080A uses the 3 I/O ports of an INS8255 Program- able Peripheral Interface (PPI) to control the auto zeroing and input data from the ADC0801 as shown in Figure 19 . The PPI is programmed for basic I/O operation (mode 0) with Port A being an input port and Ports B and C being output ports ...

Page 34

... Note 27: Switches are LMC13334 CMOS analog switches. Note 28: The 9 resistors used in the auto-zero section can be FIGURE 18. Gain of 100 Differential Transducer Preamp www.national.com the ADC0801 important that the voltage levels that drive (Continued) the auto-zero resistors be constant. Also, for symmetry, a thus logic swing convenient ...

Page 35

... FIGURE 19. Microprocessor Interface Circuitry for Differential Preamp A flow chart for the zeroing subroutine is shown in Figure must be noted that the ADC0801 series will output an all zero code when it converts a negative input [V Also, a logic inversion exists as all of the I/O ports are buff- ered with inverting gates ...

Page 36

Functional Description FIGURE 20. Flow Chart for Auto-Zero Routine www.national.com (Continued) 36 DS005671-28 ...

Page 37

Functional Description (Continued) Note 29: All numerical values are hexadecimal representations. FIGURE 21. Software for Auto-Zeroed Differential A/D 5.3 Multiple A/D Converters in a Z-80 Interrupt Driven Mode (Continued) The following notes apply: • assumed that the CPU ...

Page 38

Functional Description HEX PORT ADDRESS PERIPHERAL 00 MM74C374 8-bit flip-flop A/D 3 FIGURE 22. Multiple A/Ds with Z-80 Type Microprocessor www.national.com (Continued) HEX PORT ADDRESS This port address also ...

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Functional Description (Continued) 39 DS005671-A6 www.national.com ...

Page 40

... Physical Dimensions inches (millimeters) unless otherwise noted Order Number ADC0802LCWM or ADC0804LCWM ADC0803LCN, ADC0804LCN or ADC0805LCN www.national.com SO Package (M) NS Package Number M20B Molded Dual-In-Line Package (N) Order Number ADC0801LCN, ADC0802LCN, NS Package Number N20A 40 ...

Page 41

... NATIONALS PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant ...

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