Isolated optocoupler outputs
The Isolated optocoupler output stage of the DM6854HR consists of 3 major parts:
1. Output data register
2. Schmidt triggers
3. Optocouplers.
1. Output data register
The four bit output register holds the output pattern for the output stage. Data can
be updated and read from address (BA+3), bits 4-8. The lower bits (1-4) hold the configuration
bits of your DM6854HR. Make sure these bits are unchanged when writing to this register.
To avoid accidental changes in configuration read first data in the register (BA+3) before writing
to it.
2. Schmidt triggers
The output of the optocoupler has a Schmidt trigger to condition the output of the
optocouplers, this will reduce false triggering.
3. Optocouplers
Small SMD-optocouplers are used to isolate each channel of the isolated outputs.
Individual optocouplers are used for each channel. The optocouplers are directly connected
to the Output data register. The optocouplers are connected in a non inverting configuration
in open collector configuration. The maximum switching current is 8mA at 30V.
DM5854HR/DM6854HR Page 26 (c) RTD Finland Oy 1996-2001
