USB3803 datasheet(76/99 Pages) MICROCHIP

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USB3803

DS00001691B-page 76

 2014-2015 Microchip Technology Inc.

9.0

INTEGRATED POWER REGULATORS

9.1

Overview

The integrated power regulators are defined to provide significant flexibility to the system in providing power the device.

Several different configurations are allowed in order to align the power structure to supplies available in the system.

9.1.1

3.3V REGULATOR

The device has an integrated regulator to convert from VBAT to 3.3V.

9.1.2

1.2V REGULATOR

The device has an integrated regulator to convert from a variable voltage input on VDD_CORE_REG to 1.2V. The 1.2V

regulator shall be tolerant to the presence of low voltage (~0V) on the VDD_CORE_REG pin in order to support system

power solutions where a 1.8V supply is not always present in low power states.

The 1.2V regulator shall support an input voltage range consistent with a 1.8V input in order to reduce power consump-

tion in systems which provide multiple power supply levels. In addition the 1.2V regulator shall support an input voltage

up to 3.3V for systems which provide only a single power supply. The device will support operation where the 3.3V reg-

ulator output can drive the 1.2V regulator input such that VBAT is the only required supply.

9.2

Power Configurations

The USB3803 support operation with no back current when power is connected in each of the following configurations.

9.2.1

SINGLE SUPPLY CONFIGURATIONS

9.2.1.1

VBAT Only

VBAT should be tied to the VBAT system supply. VDD33_BYP regulator output and VDD_CORE_REG should be tied

together on the board. In this configuration the 3.3v regulator will be active, and the 3.3v to 1.2v regulator will be active.

9.2.1.2

3.3V Only

VBAT should be tied to the 3.3v system supply. VDD33_BYP and VDD_CORE_REG pins should be tied together on

the board. In this configuration the 3.3v regulator will operate in dropout. The 1.2v regulator will be active.

9.2.2

DOUBLE SUPPLY CONFIGURATIONS

9.2.2.1

VBAT + 1.8V

VBAT should be tied to the VBAT system supply. VDD33_BYP regulator output requires external

capacitor.

VDD_CORE_REG should be tied to the 1.8v system supply. In this configuration the 3.3v regulator and the 1.2V regu-

lator will be active.

9.2.2.2

3.3V + 1.8V

VBAT should be tied to the 3.3v system supply. VDD33_BYP should be connected to the 3.3v external capacitor.

VDD_CORE_REG should be tied to the 1.8v system supply. In this configuration the 3.3v regulator will operate in drop-

out. The 1.2v regulator will be active.

9.3

Regulator Control Signals

The regulators are controlled by the RESET_N and BYPASS_N signals. When RESET_N is brought high the VDD33

regulator will turn on. When RESET_N is brought low the VDD33 regulator will turn off. When BYPASS_N is brought

high, the VDD12 regulator will turn on. When BYPASS_N is brought low the VDD12 regulator will turn off.

BYPASS_N

should not be driven high if RESET_N is driven low.

USB3803 Datasheet(PDF) 76 Page - Microchip Technology

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