iHP Manual 67 | P a g e
Setting the VREF outside the valid range:
Setting the VREF value beyond the acceptable range, but not to 0V, the module will trigger a Status
CML (Communication Memory Logic) fault and will retain the existing value.
Setting the VREF value to 0V, the module will enter to standby mode. To re-enable the module, set
VREF to an acceptable range.
During a module change of output voltage:
OVP is temporary disabled until the output voltage level increases to the commanded VREF.
UVP is temporary disabled until the output voltage level decreases to the commanded VREF.
IREF will automatically readjust if the voltage request is above the nominal output voltage. This will
prevent the module from operating above the rated power.
4.4.1.1 DVS Protection Modes
When the supply is in DVS mode, the output is protected against over current, short circuit, over voltage, and
under voltage faults. The behavior of the supply during an over current fault or short circuit fault is dependent
on whether IREF is set to constant current behavior or latch behavior. In constant current mode, the module
will attempt to operate at a constant current level while reducing the output voltage and in latch mode, the
supply shut off. In the event of over voltage and under voltage faults, the supply will shut down. Please refer
to Section 8 on how to clear the fault and power up the module after fault.
4.4.1.1.1 DVS Protection Over Current Response
Over current (OC) response mode will be set by Module Command 52h (OC_RESPONSE_TYPE). The two types
of response are Constant Current and Latch. The over current level will be based on Module Command 4Dh
OC_FAULT_LIMIT_MULTIPLIER setting.
Module command 4Dh OC_FAULT_LIMIT_MULTIPLIER range is 50% to 105%
When 52h is set to Constant Current Response, the module will enter constant current mode when load
current reaches the IREF value (B2h). The output voltage will decrease to maintain the load current at the
current limit. No fault reporting occurs during this condition.
The module will revert to normal operation when load current becomes less than IREF value (B2h).
The constant current setting, IREF, is dependent on the Vout setting (VREF).
When the:
Vo (VREF) is below or equal to the nominal voltage
IREF = (Inominal) * (OC_FAULT_LIMIT_MULTIPLIER)
Vo (VREF) is above the nominal voltage, the IREF, value is automatically reduced to maintain the supply
within the maximum peak power of the module
IREF = [ (Pnominal) * (OC_FAULT_LIMIT_MULTIPLIER)] / VREF
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