PM8800 STMicroelectronics, PM8800 Datasheet - Page 27

• Manufacturer Part Number: PM8800
• Description: Integrated IEEE 802.3af compliant PoE-PD interface and PWM controller with support of external source
• Manufacturer: STMicroelectronics

PM8800A
PWM section
Figure 17. Short circuit on the output
Ch1 = 5Vout, Ch2 = SoftStart, Ch3 = VSS - GND, Ch4 = I input
When a severe over current occurs, like a short circuit of an internal power component, and
0.7 V level is reached on CS, the gate driver is instantaneously shut down and a fast hiccup
cycle is performed. When the 10 µA sink current fully discharges the SS capacitor, a new
soft-start procedure is performed.
In case of persistent severe over current, the control logic tries 4 cycles of fast hiccup before
shutting down the PWM controller at all.
To restart the device, after removing the cause of over current, VIN must be lowered under
UVLO level.
27/35