ZHCSFH8D August 2016 – January 2018 TPS25741 , TPS25741A
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
OCP protection is enabled tVP after the voltage on the VBUS pin has exceeded VBUS_RTH, see Figure 38. Prior to OCP being enabled, the GD pin can be used to protect against a short.
The OCP protection circuit monitors the differential voltage across an external sense resistor to detect when the current outflow exceeds VITRIP which in turn activates an over-current circuit breaker and disables the GDNG / GDNS gate driver. Once the OCP is enabled, if the voltage on the VBUS pin falls below VBUS_FTH then that is also treated like an OCP event.
Following the recommended implementation of a 5 mΩ sense resistor, when the device is configured to deliver 3 A (via HIPWR pin), the OCP threshold lies between 3.8 A and 4.5 A. When configured to deliver 5 A (via HIPWR pin), the OCP threshold lies between 5.8 A and 6.8 A. The sense resistor may be increased to tighten the OCP threshold.