TPS65982ABZBHR datasheet(58/121 Pages) TI1

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LDO

LDO_1V8D

LDO_3V3_VB_EN

LDO

VREF

Digitally

adjustable

trip Point

VREF

LDO_1V8D_EN

LDO

VREF

LDO_1V8A

VBUS

LDO_1V8A_EN

VREF

VIN_3V3

VOUT_3V3

LDO_3V3

To Digital Core

TPS65982

SLVSD02D – MARCH 2015 – REVISED JUNE 2019

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9.3.5 Power Management

The TPS65982 Power Management block receives power and generates voltages to provide power to the

TPS65982 internal circuitry. These generated power rails are LDO_3V3, LDO_1V8A, and LDO_1V8D. LDO_3V3

is also a low power output to load flash memory. VOUT_3V3 is a low power output that does not power internal

circuitry that is controlled by application code and can be used to power other ICs in some applications. The

power supply path is shown in Figure 49.

Figure 49. Power Supply Path

The TPS65982 is powered from either VIN_3V3 or VBUS. The normal power supply input is VIN_3V3. In this

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

LDO steps the voltage down from LDO_3V3 to LDO_1V8D and LDO_1V8A to power the 1.8 V core digital

circuitry and 1.8 V analog circuits. When VIN_3V3 power is unavailable and power is available on the VBUS, the

TPS65982 will be powered from VBUS. In this mode, the voltage on VBUS is stepped down through an LDO to

LDO_3V3. Switch S1 in Figure 49 is unidirectional and no current will flow from LDO_3V3 to VIN_3V3 or

VOUT_3V3. When VIN_3V3 is unavailable, this is an indicator that there is a dead-battery or no-battery

condition.

9.3.5.1 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. In addition to the POR and supervisory circuits for the internal supplies, a separate

programmable voltage supervisor monitors the VOUT_3V3 voltage.

9.3.5.2 Supply Switch-Over

VIN_3V3 takes precedence over VBUS, meaning that when both supply voltages are present the TPS65982 will

power from VIN_3V3. Refer to The Figure 49 for a diagram showing the power supply path block. There are two

cases in with a power supply switch-over will occur. The first is when VBUS is present first and then VIN_3V3

becomes available. In this case, the supply will automatically switch-over to VIN_3V3 and brown-out prevention

is verified by design. The other way a supply switch-over will occur is when both supplies are present and

VIN_3V3 is removed and falls below 2.85 V. In this case, a hard reset of the TPS65982 occurs prompting a re-

boot.

9.3.5.3 RESETZ and MRESET

The VIN_3V3 voltage is connected to the VOUT_3V3 output by a single FET switch (S2 in Figure 49).

TPS65982ABZBHR Datasheet(PDF) 58 Page - Texas Instruments

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