Pepper Computer Modular Computers RS232 User Manual

SMART I/O User’s Manual

©1996 PEP Modular Computers GmbH

October 01, 1996

Page 5 - 109

Chapter 5  Analog Modules

The SM-DAC1 has 2, 4 or 6 differential voltage or current outputs depending

on the ordered type. An on-board EEPROM contains board specific calibra-

tion data, module ID byte, sub ID byte and production data. A DC/DC

converter generates the 5V to 

±

15V power requirements for the D/A con-

verter and provides additional system isolation.

The output stage of the SM-DAC1 comprises a fast D/A converter followed

by a software controlled switch that ensures the on-board op-amp remains

inactive and produces 0V at it’s output during power-up. The current version

has an additional MOSFET after this op-amp.

The current version of this module utilizes current sensing that detects open

loads or broken lines. The individual comparators of this sensing circuit

alarm the software when currents below 4mA are detected.

DAC

System

Interface

Operational

Amplifier

AGND

Software

Controlled

Switch

Output