STUSBCD01B データシートの表示（PDF） - STMicroelectronics

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STUSBCD01B

USB charger detection interface

STMicroelectronics 

STUSBCD01B

3

Functional description

Functional description

The STUSBCD01B is designed to provide USB charger detection functionality to USB

platforms which do not have this feature integrated in the PHY. The device can work with a

supply voltage ranging from 2.2 V to 4.5 V and has an internal regulator which generates the

1.8 V voltage required for the internal blocks and state machine.

The STUSBCD01B can detect a dedicated charger or a Host/Hub charger connected to

USB data lines and provides both an open drain pin and a digital I/O pin for the detection

output signal. The open drain output can be disabled using the /OE input signal.

Two different detection methods, selectable through the STATUS/METHOD pin, are

implemented in order to distinguish between a dedicated charger and a Host/Hub charger. If

the interface voltage is not present the detection method is defined by the status of default

method pin.

The STUSBCD01B features very low power consumption in Standby mode and low input

capacitance on DP/DM pins. An over voltage protection circuit is also implemented on the

VBUS pin in order to limit VBUS voltage to 6 V and provide protection to external devices

connected to it.

3.1

Detection methods

The STUSBCD01B implements a current source/sink method to detect dedicated chargers

(wall chargers) and a current sink method for Host/Hub chargers (based on USB battery

charging spec v1.0). If a standard Host/Hub is connected to the device it is recognized

thanks to its pull-down resistors on DP/DM lines and therefore DETECT/STATUS outputs

will be low.

3.2

Dedicated charger detection method

Selected driving method pin low during the falling edge of shutdown or driving default

method pin low if VIO is not present. The dedicated charger detection method uses a current

source on DP pin and a current sink on DM pin to detect the resistor (max 200 Ω) which

connects DP and DM in dedicated chargers.

3.3

Current sink method

Selected driving method pin high during the falling edge of shutdown or driving default

method pin high if VIO is not present. A voltage source of VDAT_SRC is connected to DP

and a current of IDAT_SINK is drawn from DM.

If a Host/Hub charger is connected, STUSBCD01B will see a voltage of VDAT_SRC on pin

DM. The same happens if a dedicated charger is connected and, therefore, in order to

distinguish between the two, if the current sink method detection is successful it is

necessary to run the dedicated charger detection method immediately after.

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