TPS25751D datasheet(35/89 Pages) TI1

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8.3.3.3.1 Overvoltage Protection (OVP)

The application firmware enables the OVP and configures it based on the expected VBUS voltage. If the

voltage on VBUS surpasses the configured threshold VOVP4VSYS = VOVP4RCP/rOVP, then GATE_VSYS

is automatically disabled within tPPHV_FSD to protect the system. If the voltage on VBUS surpasses the

configured threshold VOVP4RCP, then GATE_VBUS is automatically disabled within tPPHV_OVP. When

VVBUS falls below VOVP4RCP - VOVP4RCPH, GATE_VBUS is automatically re-enabled within tPPHV_ON

because the OVP condition has cleared. This action allows two sinking power paths to be enabled

simultaneously and GATE_VBUS disables when necessary to ensure that VVBUS remains below VOVP4RCP.

While the TPS25751D is in BOOT mode in a dead-battery scenario (that is VIN_3V3 is low), it handles an

OVP condition slightly differently. As long as the OVP condition is present, GATE_VBUS and GATE_VSYS are

disabled. Once the OVP condition clears, both GATE_VBUS and GATE_VSYS are re-enabled. Because this is

a dead-battery condition, the TPS25751D draws approximately IVIN_3V3, ActSnk from VBUS during this time to

help discharge it.

VOVP4VSYS = VOVP4RCP / rOVP

Power Path Supervisor

VOVP4RCP

Figure 8-18. Diagram for OVP Comparators

8.3.3.3.1.1 Reverse-Current Protection (RCP)

The VSYS gate control circuit monitors the PPHV and VBUS voltages and detects reverse current when the

VVSYS surpasses VVBUS by more than VRCP. When the reverse current condition is detected, GATE_VBUS is

disabled within tPPHV_RCP. When the reverse current condition is cleared, GATE_VBUS is re-enabled within

tPPHV_ON. This action limits the amount of reverse current that can flow from PPHV to VBUS through the

external N-ch MOSFETs. In reverse current protection mode, the power switch controlled by GATE_VBUS is

allowed to behave resistively until the current reaches VRCP/ RPPHV and then blocks reverse current from

PPHV to VBUS.

-VRCP

1/RPPHV

VRCP/RPPHV

V=VVBUS ± VPPHV

Figure 8-19. Switch I-V Curve for RCP on Sink-path Switches.

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TPS25751

SLVSH93 – OCTOBER 2023

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