Chapter 5 Analog Modules | SMART I/O User’s Manual |
| | | | |
| | | | |
5.4.5 Functional Description
The SM-ADC1 has 6 differential voltage or current inputs depending on the ordered type. An on-board EEPROM contains board specific calibration data, module ID byte, sub ID byte and production data. A DC/DC converter generates the 5V to ±15V power requirements for the ADC converter and provides additional system isolation.
5.4.5.1 Input Circuitry
The input circuitry of the SM-ADC1 consists of an R-C first-order, low-pass filter to prevent noise and signals greater than 10kHz from entering the system, a 1:6 channel multiplexer, followed by a differential amplifier, divider and a 12-bit fast analog to digital converter (ADC).
Figure 5.4.5.1: SM-ADC1 Input Shematic Diagram
+
Low Pass
-Filter
Single
Ended
AGND
The ADC, using successive approximation and input track and hold is referenced by its own on-chip voltage source supplying 4.096V. To cater for bipolar full-scale inputs, this reference source is split (-2.048V .. +2.048V).
The incoming voltage signals are multiplexed and reduced via a 1:5 divider network so that the ADC is supplied with a scalable input voltage range.
| | | |
October 01, 1996 | ©1996 PEP Modular Computers GmbH | Page 5 - 91 |
| |
