Figure 7-1 depicts the
device VISO regulation behavior across the output load range, including
when the output is overloaded. For proper device operation, ensure that the device
VISO output load does not exceed the maximum output current (IOUT_MAX).
The value for IOUT_MAX over different temperature and VINP
conditions are shown from Figure 6-8 to Figure 6-11. The following
protection mechanisms will be engaged if the UCC12051-Q1 is loaded beyond the
recommended operating area:
- The device limits the maximum output power. If a load exceeding IOUT_MAX is applied, VISO drops accordingly to meet the maximum power limit.
- If VISO drops below nominal 3.8 V while operating in the constant
power limit region, the over-power fold-back feature will switch the power
converter from active rectification to passive rectification, and the built-in
recovery hysteresis will ensure the UCC12051-Q1 recovers at a lower output
power. The device returns to active rectification when load drops and
VISO increases above nominal 4.3 V.
- The device triggers a soft-start reset if VISO drops below the nominal 1.8-V threshold. This reset is designed to protect the device during VISO short-circuit conditions.
- Thermal shutdown protection disables the converter if the device is operated in any of the above regions long enough to raise the silicon junction temperature above the thermal shutdown threshold. See the Section 7.3.4 section for more details on this device feature.
Figure 7-1 VISO Load Recommended Operating Area Description