AN2115 Datasheet, PDF (17/33 Pages) STMicroelectronics – This application note details the main features

AN2115
Synchronization
Equation 9
V_out
=
0.6
•
⎛
⎝
1
+
RR_{-----32-⎠⎞}
Thanks to the very low FB leakage current (25 nA), high R₃ and R₂ values can be chosen
(hundreds of kΩ) which increase system efficiency at very low load.
5.4
OVP (overvoltage protection)
The device is equipped with an internal overvoltage protection circuit to protect the load. If
the voltage at the feedback pin goes higher than an internal threshold set at 10% (typ.)
higher than the reference voltage, the low side MOSFET is turned on until the feedback
voltage goes lower than the reference voltage. During overvoltage circuit intervention, the
zero crossing comparator is disabled so that the device is also able to sink current.
5.5
Thermal shutdown
The device also has thermal shutdown protection, which is activated when the junction
temperature reaches 155 °C. In this case both the high and low side MOSFETs are turned
off.
Once the junction temperature goes back below 95 °C, the device resumes normal
operation.
Doc ID 11165 Rev 5
17/33