34825 datasheet(16/39 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

34825

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

The 34825 has five operational modes: Power Down

mode, VBUS Power mode, Standby mode, Active mode, and

Power Save mode. The mode transition diagram is given in

Figure 13.

VDD > VVDDPOR

Active

VDD < VVDDPOR

ID det or VBUS det

VDD < VVDDPOR

Standby

I2C resets ACTIVE bit or

detachment of accessory

Power

Down

VBUS

Power

VDD > VVDDPOR

VBUS power up

VBUS power down

Power

Save

I2C or detection

of no activity

I2C or detection

of the activity

Detachment

of accessory

Figure 13. Mode Transition Diagram

POWER DOWN MODE

The Power Down mode is when neither the VDD pin nor

the VBUS pin is powered. In this mode, the IC does not

respond to any accessory attachment except for a power

supply. When an external power supply is plugged into the

mini or micro-USB connector, the 34825 enters the VBUS

Power mode.

VBUS POWER MODE

The 34825 enters the VBUS Power mode when the VBUS

pin is powered but the VDD pin is not. In the VBUS Power

mode, the internal power MOSFET is turned on to power the

charging function in the cell phone. The ISET pin outputs

high-impedance in this mode.

STANDBY MODE

The Standby mode is when the VDD voltage is higher than

the POR (Power-On-Reset) threshold and no accessory is

attached. In this mode, only the ID detection circuit, the I2C

interface, and the internal registers are powered in order to

minimize the quiescent current from the VDD pin. The ID

detection circuit samples the status of the ID line every

50 ms.

If detecting an attachment of an accessory, the 34825

moves to the Active mode for further accessory identification.

ACTIVE MODE

The Active mode starts when an accessory is plugged into

the mini or micro-USB connector while the VDD pin is

powered. The 34825 identifies the accessory and interrupts

the host IC for further actions. Different functions will be

enabled according to the identification result, so the

quiescent current in Active mode is dependent on the type of

accessories.

The operational mode can be changed from Active to

Standby either by an accessory detachment or by resetting

the ACTIVE bit to 0 through an I2C programming operation.

POWER SAVE MODE

The Power Save mode can be enabled only for

accessories with a remote controller (refer to Table 21). The

34825 enters into the Power Save mode to minimize the

operating current while such an accessory is attached, but

not in operation. For example, if the cell phone is not in an

audio playback mode when a headset is attached, the host IC

can force the 34825 to the Power Save mode via the I2C

programming. The 34825 can also automatically enter into

the Power Save mode when no activity is detected on the

SPK_R or SPK_L pins in 10 seconds. The VDD current in the

Power Save mode is slightly higher than the current in the

Standby mode.

The 34825 can exit the Power Save mode by an I2C

programming or will exit the mode automatically when

34825 Datasheet(PDF) 16 Page - Freescale Semiconductor, Inc

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