TPS25751D datasheet(30/89 Pages) TI1

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LDO

LDO_1V5

LDO

VREF

VIN_3V3

LDO_3V3

VBUS

RLDO_3V3

Figure 8-11. Power Supplies

The TPS25751 is powered from either VIN_3V3 or VBUS. The normal power supply input is VIN_3V3. When

powering from VIN_3V3, current flows from VIN_3V3 to LDO_3V3 to power the core 3.3-V circuitry and I/Os. A

second LDO steps the voltage down from LDO_3V3 to LDO_1V5 to power the 1.5-V core digital circuitry. When

VIN_3V3 power is unavailable and power is available on VBUS, it is referred to as the dead-battery start-up

condition. In a dead-battery start-up condition, the TPS25751 opens the VIN_3V3 switch until the host clears

the dead-battery flag through I2C. Therefore, the TPS25751 is powered from the VBUS input with the higher

voltage during the dead-battery start-up condition and until the dead-battery flag is cleared. When powering from

a VBUS input, the voltage on VBUS is stepped down through an LDO to LDO_3V3.

8.3.2.1 Power-On And Supervisory Functions

A power-on reset (POR) circuit monitors each supply. This POR allows active circuitry to turn on only when a

good supply is present.

8.3.2.2 VBUS LDO

The TPS25751 contains an internal high-voltage LDO which is capable of converting VBUS to 3.3 V for powering

internal device circuitry. The VBUS LDO is only used when VIN_3V3 is low (the dead-battery condition). The

VBUS LDO is powered from VBUS.

8.3.3 Power Paths

The TPS25751 has internal sourcing power paths: PP_5V and PP_CABLE. TPS25751D has a integrated

bidirectional high voltage load switch for sinking power path: PPHV. TPS25751S has a high voltage gate driver

for sink path control: PP_EXT. Each power path is described in detail in this section.

8.3.3.1 Internal Sourcing Power Paths

Figure 8-12 shows the TPS25751 internal sourcing power paths available in both TPS25751D and TPS25751S.

The TPS25751 features two internal 5-V sourcing power paths. The path from PP5V to VBUS is called PP_5V.

The path from PP5V to CCx is called PP_CABLE. Each path contains two back-to-back common drain N-FETs,

with current clamping protection, overvoltage protection, UVLO protection, and temperature sensing circuitry.

PP_5V can conduct up to 3 A continuously, while PP_CABLE can conduct up to 315 mA continuously. When

disabled, the blocking FET protects the PP5V rail from high-voltage that can appear on VBUS.

TPS25751

SLVSH93 – OCTOBER 2023

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