Pepper Computer RS232, RS485 user manual SM-DAC1 Output Shematic Diagram

Chapter 5 Analog Modules SMART I/O User’s Manual

5.5.5 Functional Description

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.

5.5.5.1 Output Circuitry

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.

Figure 5.5.5.1: SM-DAC1 Output Shematic Diagram

System

Interface

DAC

Software

Controlled

Switch

Operational

Amplifier

Output

AGND

5

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.

October 01, 1996 ©1996 PEP Modular Computers GmbH Page 5 - 109