FSA9280A Ver la hoja de datos (PDF) - Fairchild Semiconductor

Número de pieza

componentes Descripción

Fabricante

FSA9280A

USB Port Multimedia Switch Featuring Automatic Select and Accessory Detection

Fairchild Semiconductor 

2. Power-up & Reset

The FSA9280A does not need special power sequencing for

correct operation. The main power of the device is provided

by either VBUS_IN or VBAT. If VBUS_IN is not present and VBAT is

applied, VBAT is used to power the device. VDDIO is only used

for I2C interface and interrupt processing.

Table 1 summarizes the enabled features of each power

state of the FSA9280A. The valid voltages levels for each

power supply can be found in Section 9.2.

Table 1 – Power States Summary

Valid

VBUS_IN

NO

NO

Valid

VBAT

NO

NO

Valid

VDDIO(1)

NO

YES(2)

Power

State

Power Down

Charging

through FET

NO

Enabled Functionality

Processor Communication

(I2C & Interrupts)

NO

ILLEGAL STATE

NO

YES

NO

Powered from VBAT

NO

NO

YES

YES

Powered from VBAT

NO

YES

NO

NO

Powered from VBUS_IN

Yes

YES

YES

YES

NO

NO

YES(2)

Powered from VBAT

Powered from VBUS_IN

YES

YES

YES

YES

YES

Powered from VBAT

YES

Notes:

1. VDDIO is expected to be the same supply used by the baseband I/O‟s.

2. This is not a typical state: both VBAT and VDDIO are typically provided simultaneously.

NO

YES

NO

NO

YES

YES

Detection

NO

YES

YES

YES

YES

YES

YES

2.1. Reset

When the device is reset, all the registers are initialized to

the default values shown in Table 7 and all switch paths are

open. After reset or power up, the FSA9280A enters

Standby Mode and is ready to detect accessories sensed on

its VBUS_IN and / or ID_CON pins.

2.1.1. Hardware Reset

There are three hardware reset mechanisms:

 Power-on reset caused by the initial rising edge of VBUS

or VBAT

 The falling edge of VDDIO.

 With VDDIO valid, driving both I2C_SDA and I2C_SCL

signals LOW for at least 30ms.

Note:

3. I2C controllers that implement clock stretching could

cause reset. In this case, GPIOs could be used for the

I2C interface.

2.1.2. Software Reset

The device can be reset through software by writing to the

Reset bit in the Register (1BH).

© 2009 Fairchild Semiconductor Corporation

FSA9280A • Rev 1.1.0

6

www.fairchildsemi.com

Share Link: