SLUSDQ7B May 2020 – December 2023 TPS566231 , TPS566238
PRODUCTION DATA
The TPS56623x has overcurrent protection and undervoltage protection. The output overcurrent limit (OCL) is implemented using a cycle-by-cycle valley detect circuit. The switch current is monitored during the OFF state by measuring the low-side FET drain-to-source voltage. This voltage is proportional to the switch current. To improve accuracy, the voltage sensing is temperature compensated.
During the on-time of the high-side FET switch, the switch current increases at a linear rate determined by the following:
There are some important considerations for this type of overcurrent protection. When the load current is higher than the overcurrent threshold by one half of the peak-to-peak inductor ripple current, the OCL is triggered and the current is limited. The output voltage tends to drop because the load demand is higher than what the converter can support. When the output voltage falls below 60% of the target voltage, the UVP comparator detects it and the device shuts off after a 256-μs wait time. The device then restarts after the hiccup time (typically 7 × Tss). When the overcurrent condition is removed, the output is recovered.