6.5.2

Output enable (OUT_EN)

This pin provides a fast way to disable all the outputs simultaneously. When the OUT_EN pin is driven low for at

least tW(OUT_EN), all eight outputs are disabled. This timing execution is compatible with an external reset push

from the operator, safety requirements, and permits, in a PLC system, a micro-controller polling for obtain all

internal information during a reset procedure.

Note that the OUT_EN signal acts as a reset for the internal data register driving the output switches: when the

OUT_EN is low, SDO is pulled down and the output stage is forced OFF. To re-enable SDO, it is necessary to

raise the OUT_EN pin; to enable the output stage again, it is then necessary to raise the OUT_EN pin and send

the desired output configuration by an SPI command.

Figure 10. OUT_EN without effect on output

Figure 11. OUT_EN effective on output channel

6.6

FAULT and PGOOD indications

The FAULT pin is an active low open drain output indicating fault conditions. This pin is activated when at least

one of the following conditions occurs:

•

Junction over-temperature (TJX >TJSD) of one or more channels of the Process Stage.

•

No module-8 SPI communication (the number of bits sent through the SDI is not a multiple of 8)

•

Internal communication error. In fact, the IC is able to identify (and report to the micro-controller) if any

errors occur in the data transmission between isolation. When it occurs, the output stage maintains the

previous ON/OFF status.

The PGOOD pin is an active low open drain output indicating if the supply voltage of the Process Stage chip is

lower than the internal threshold (see Figure 12).

Note:

When SS signal is low the transmission between Control Logic Stage and Process Stage is inhibited and the

status of PGOOD is not refreshed (PGOOD refresh time < 120 µs).

ISO808A, ISO808A-1

FAULT

and PGOOD indications

DS14170 - Rev 1

page 17/38