STOTG04E datasheet(14/26 Pages) STMICROELECTRONICS

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Block description

STOTG04E

14/26

Block description

The STOTG04 integrates a charge pump and comparators for the VBUS, ID line detector and interrupt

switch, differential data driver, differential and single-ended receivers, low dropout voltage regulator and

control logic. The STOTG04 provides a complete solution for connection of a digital USB OTG controller

to the physical Universal Serial Bus.

6.1

Charge pump

The VBUS line voltage is provided using the internal charge pump. It is capable of sourcing up to 35mA

load current. The charge pump can be powered by voltage from 2.7V to 5.5V. It needs two capacitors for

its operation: an external capacitor of 220nF connected between the CAP1 and CAP2 pins and a 4.7µF

decoupling tank capacitor on the VBUS. If an application needs current that is higher than 35mA, an

external charge pump or a switch controlled by the ADR_PSW pin may be used.

6.2

VBUS Comparators

These comparators monitor the VBUS voltage. They provide current status information for the VBUS line.

VBUS valid status means that the voltage is above VBUS_VLD. Session valid status means that the VBUS

voltage is above VSES_VLD level.

6.3

Voltage regulator

An internal low-dropout voltage regulator provides power for the bus drivers and receivers. The regulator

needs an external capacitor of 1µF on the VTRM pin for proper operation. The regulator can provide 3.3V

or 2.75V output voltages according to 2V7_en bit in Control Register 3.

The regulator can be bypassed by tying the VTRM pin to the VBAT power supply voltage when the analog

supply voltage is in the range of 3.0V (or 2.7V) to 3.6V.

6.4

ID Line detector

This block senses ID line status. It is capable of detecting three different line states:

• pin floating;

• pin tied to ground;

• pin grounded via a 140k

Ω resistor.

The ID detector can also generate an interrupt by shorting the pin to ground.

6.5

Driver and receivers

The driver can operate in several different modes. It can act as a simple low-speed and full-speed

differential USB driver, as two independent single-ended drivers in the UART mode, or as an open-drain

driver in the I2C mode.

This block contains one differential receiver for the USB operation mode and two single-ended receivers

for USB signaling as well as UART and I2C receivers.

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