Datasheet

78M6610+PSU Data Sheet
2.12 Relay Control
The firmware includes relay control logic and provides a digital output RELAYCTRL for controlling a relay.
The relay control may operate in either an autonomous mode or in a slave mode. The operating mode is
selected by the setting of the AUTORELAY bit in the COMMAND register. A bit in the ALARMS register
reports the state of the RELAYCTRL output.
2.12.1 Autonomous Mode
When autonomous relay control mode is enabled, the 78M6610+PSU firmware controls the state of
RELAYCTRL output, based upon the input line voltage.
At power on, RELAYCTRL output is inactive. When the RMS voltage is within specified upper and lower
turn-on thresholds (RelayOnMin, RelayOnMax) for a specified time (RelayOnTime), RELAYCTRL output
will be activated. Should the RMS voltage exceed the specified turn-off thresholds (RelayOffMin,
RelayOffMax) for a specified time (RelayOffTime), RELAYCTRL output will be deactivated. The turn-on
and turn-off thresholds are specified separately, as are delay times, to provide hysteresis to prevent
unwanted switching of the relay due to short-term fluctuations in voltage.
The autonomous mode can be used to automatically control the in-rush current relay as shown in
Figure
2-9.
AC INLET
TO PFC
78
M6610+PSU
SHUNT
+Vcc
Figure 2-9: Relay Control for In-rush Current Limitation Circuitry
2.12.2 Slave Mode
When slave mode relay control is selected, the RELAYCTRL output is manually controlled by setting or
clearing the RELAY_ON bit in the AlarmSet and AlarmReset registers.
2.12.3 Activation Delay
The relay control logic allows setting a delay time for energizing and de-energizing the relay. The delay
time for energizing and de-energizing the relay is relative to the zero crossing of the Voltage as shown in
Figure 2-10
.
The time specified in the registers is expressed in the number of high-rate samples.
The default timings are:
Energized delay time (RelayOnDelay) = 0x000000 sample counts
De-Energized delay time (RelayOffDelay) = 0x000000 sample counts
18 Rev 3