34825 datasheet(13/39 Pages) FREESCALE

13 / 39 page

Analog Integrated Circuit Device Data

Freescale Semiconductor

34825

FUNCTIONAL DESCRIPTION

INTRODUCTION

FUNCTIONAL DESCRIPTION

INTRODUCTION

The 34825 is designed to support cell phones that adopt

the micro or mini-USB connector as the sole wired interface

between the cell phone and external accessories. Using the

micro-USB connector for charging and USB data

communication is required by the OMTP standard for the

UCS. The 34825 further extends the micro-USB connector to

support other accessories to eliminate all other mechanical

connectors in a cell phone. The supported accessories

include various audio headsets, UART connection, R/D test

cables for firmware downloading, and other user defined

accessories, in addition to the chargers defined in the Battery

Charging Specification, Revision 1.0, from the USB

Implementer’s Forum and the CEA-936-A USB Carkit

Specification, from the Consumer Electronics Association

(CEA). The supported chargers are listed in Table 7.

The 34825 offers two mechanisms to assist the

identification of the accessory. The ID detection mechanism

allows the cell phone to measure the ID resistor value

between the ID pin and the ground with a 5-bit ADC. The

VBUS detection mechanism allows the cell phone to find out

the connection status between the D+ and D- pins. Together,

the exact accessory can be determined. A detection flow is

initiated by a change in the VBUS pin voltage or by a change

in the ID pin floating status. Detaching the accessory from the

micro or mini-USB connector causes the VBUS voltage or/

and the ID resistance to change. The identification flow will be

initiated to confirm if an accessory is still connected. The host

can also initiate the identification flow by resetting an ACTIVE

bit in the register from 1 to 0.

Upon the completion of the identification flow, an interrupt

signal is sent to the host IC, so the host IC can take further

actions. The 34825 contains switches that the host IC can

control via an I2C interface. Based on the accessory, the host

IC can configure the switch connections in the 34825, so that

the signal paths for the USB communication, or the UART

communication, or audio accessories can be established

between the micro or mini-USB connector pins and the

system ICs. If the accessory is a power supply, the supplied

voltage is switched to the Li-ion battery charging function in

the cell phone via an internal power MOSFET.

The host IC controls the 34825 via the I2C serial bus. The

device and the control bits that the host IC can access to

control the 34825.

FUNCTIONAL PIN DESCRIPTION

SPEAKER RIGHT CHANNEL (SPK_R)

Right channel of the baseband speaker output.

SPEAKER LEFT CHANNEL (SPK_L)

Left channel of the baseband speaker output.

MICROPHONE OUTPUT (MIC)

Microphone output to the baseband.

D+ OF THE USB TRANSCEIVER (D+)

D+ line of the USB transceiver.

D- OF THE USB TRANSCEIVER (D-)

D- line of the USB transceiver.

UART RECEIVER (RXD)

Receiver line of the UART.

UART TRANSMITTER (TXD)

Transmitter line of the UART.

TEST2 INDICATOR (TEST2)

Push-pull output to indicate the type of the connected test

cable.

IO POWER SUPPLY (VDDIO)

Power supply input for the logic IO interface. Generally the

IO power supply voltage should be the same as the IO

voltage used in the cell phone system. VDDIO is also one of

the hardware reset input sources. A falling edge at this pin will

reset the 34825. See Reset for more information.

TEST1 INDICATOR (TEST1)

Open-drain output to indicate the attachment of a test

cable.

POWER SUPPLY (VDD)

Power supply input. Bypass to ground with a 1.0

μF

capacitor.

INTERRUPT OUTPUT (INT)

Active low open-drain output. The INT pin sends an

interrupt signal to the host IC when an interrupt event

happens. The INT output returns to high voltage once all

interrupt bits are read.

DATA LINE OF THE I2C INTERFACE (I2C_SDA)

Data line of the I2C interface.

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