ISO8200B

Functional description

Doc ID 023802 Rev 1

17/33

6.1.3

Output synchronization (SYNC)

The input is active low; it enables the ISO8200B transmission buffer to load the present data

of the input buffer and manages the transmission between the two isolated sides of the

device.

6.1.4

Watchdog

The isolated side of the device provides a watchdog function in order to guarantee a safe

condition when Vdd supply voltage is missing.

until a new update request is received.

The refresh signal is also considered a valid update signal, so the isolated side watchdog

does not protect the system from a failure of the host controller (e.g. MCU freezing).

Figure 7.

Watchdog behavior

6.1.5

Output enable (OUT_EN)

This pin provides a fast way to disable all the outputs simultaneously. When the OUT_EN

pin is driven low the outputs are disabled. To enable the output stage, it is then necessary to

raise the OUT_EN pin. This timing execution is compatible with an external reset push from

the operator, safety requirement, and permits in a PLC system, a microcontroller polling to

obtain all internal information during a reset procedure.

Figure 8.

Output channel enable timing

WD

SYNC

INPUT

OUTPUT

Timer

start

Timer

restart

Old data

New data

Old data

New data

tw(Sync)

WD

SYNC

INPUT

OUTPUT

Timer

start

Timer

stop

twd

tw(Sync)

Old data

New data

Outputs off

New data

AM14895v1

OUT_EN

tw(OUT_EN)

OUTx

tp(OUT_EN)

t

t

AM14896v1