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12-Bit 8-Input Programmable-Gain A/D Converter and Counter/Timer Card


  • Eight single-ended or differential analog inputs
  • 12-bit resolution
  • Nine software programmable voltage ranges
  • Programmable scan rate
  • Foreground/background operation
  • Three 16-bit counter/timers for event counting, pulse and waveform generation, and frequency measurement.
  • Seven bits of digital I/O
  • Can assert interrupts

The AD12-8G is an eight-channel, 12-bit, analog/digital card for use in IBM Personal Computers. It is a 3/4 length card that can be installed in expansion slots of ISA-bus computers. All connections are made through a standard 37-pin D type connector that projects through the rear of the computer.


The input analog channels are individually switch selectable for either differential or single-ended input signals. A choice of nine software-selectable voltage ranges are available and the card can withstand ±30 VDC overload and transients of several hundred volts. The A/D converter is a successive-approximation type with solid-state input analog multiplexer and sample and hold amplifier. A/D conversion time is typically 25 microseconds.


This card also contains a type 8254 counter/timer chip which has three 16-bit counters. These counters can be used as an A/D pacer clock and/or can be used to measure pulse width, count events, measure or generate frequencies, etc. An on-board 1 MHz crystal controlled clock is hard-wired to one counter input and the clock inputs to the other two counters are available at the I/O connector. All the gate inputs and counter outputs are accessible at the I/O connector.


AD12-8G also can accept three bits of digital input and can provide four bits of digital output both in standard TTL/CMOS logic levels. One of these outputs, for example, can be used to initiate an interrupt upon end of A/D conversion. Jumper positions on the card provide means to assert interrupts on your choice of levels 2 through 7.


Analog Inputs

  • Number of Channels: Eight differential or single- ended, individually DIP switch selectable for S.E. or Diff.
  • Voltage Range: Programmable, ±5V (default), ±10V, ±0.5V, ±0.05V, ±0.01V, 0-10V, 0-1V, 0-0.1V, 0-0.02V.
  • Overvoltage Protection: ±30 VDC.
  • Input Impedance: 10 Megohm or 125 nA at 25°C.
  • Common Mode Rejection Ratio: 90 db when gain = 1; 125 db when gain = 100.
  • Multiplexer/Sample and Hold Settle Time: When gain = 1 : 30 µSec; When gain = 100 : 95 µSec
  • Overall Accuracy: ±0.05% of full scale.
  • Linearity: ±1 LSB.
  • Resolution: 12 bit binary.
  • A/D Trigger Source: Software selectable, external trigger, programmable timer, or program command.
  • Conversion Time: 35 µSec max., 25 µSec typical.
  • Temperature Coefficient: ±10 µV per °C zero stability. ±25 µV per °C gain stability.

Digital I/O

  • Logic Low: 0 to 0.8V at -0.4 mA max.
  • Logic High: 2.4 to 5V at 20 µA max.
  • Logic Low: 0 to 0.5V at 8 mA sink.
  • Logic High: 2.4 to 5V at 0.4 mA source.

Counter Timer

  • Type: 8254 type programmable interval timer, three 16-bit counters.
  • Drive Capability: 5 LSTTL loads (2.5 mA at 0.80 VDC).
  • Input Load (Gate and Clock): ±10 µA, TTL/CMOS compatible.
  • Input Clock Frequency: 10 MHz max.
  • Active Count Edge: Negative edge.
  • Clock Pulse Width: 30 nSec high / 50 nSec low min.


  • Level: Jumper selectable, levels 2-7.
  • Enable/Disable: Via software. (INTE bit of Control Register. Service routines should acknowledge and re-enable interrupts.)
  • Source: External, positive edge triggered.


  • Operating Temperature Range: 0° to 60°C.
  • Storage Temperature Range: -40° to 100°C.
  • Humidity: 0 to 95% RH, non-condensing.

Power Required

  • 5 VDC at 180 mA max.
  • 12 VDC at 500 mA max.


  • 9.0 inches long. (229mm)
  • Requires full-size slot.

Regulatory Compliance

  • This product is in full compliance with CE requirements.

Part NumberPrice(USD)
View / Download Manual (in .pdf format)
Acquisition Control Communications Engineering / Systems
USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1280
Point Roberts, WA 98281

Western Canada - Vancouver BC

Tel:1.800.663.6001 or 1.604.925.6150
Address: 2454 Haywood Ave
West Vancouver, BC V7V 1Y1

Eastern Canada - Markham, Ontario

Tel:1.800.465.0164 or 1.905.513.7027