V
OLTECH
AC
I
NTERFACE
U
SER
M
ANUAL
98-072
ISS
7
PAGE
39
Control Timing
The diagram above shows the signal levels (high or low) and the times between them from when the
AT3600/AT5600 asserts its enable signal. The Enable In (from AT) is not visible on any ACIF ports. It is a
control line that comes in from the AT3600/AT5600 peripheral port.
When the AT initiates an external source test, it asserts Enable In and leaves this signal high until the end of
the test. Within a few microseconds of 'Enable In', the Isolator Control line is also asserted. This line can
therefore be used to control an external isolating switch like the relays in the AC Interface itself. In fact, this
signal is used internally to switch these relays.
20mS after the 'Enable In' and 'Isolator Control' lines are activated, the 'External Source Enable' signal is
activated. The ESE line must be used to go to a control port on an external source or to switch a device that
applies power from an external source, where control is not possible.
The 20mS delay ensures that the AC Interface relays, or another external device connected to the Isolator
Control signal have switched completely before an external source is activated, which ensures that the isolator
does not switch the current on to the load.
As soon as Enable In goes low, the ESE signal is switched to low within microseconds, turning the external
source off as quickly as possible. The Isolator Control line remains high for another 100mS to allow time for
the source to switch off and any transients to decay.
100m
S
20mS
Enable In from AT
Isolator Control
External Source
E bl
