34825 datasheet(20/39 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

34825

FUNCTIONAL DEVICE OPERATION

ACCESSORY IDENTIFICATION

When the ADC result is 00000, the resistance between the

ID pin and the ground is less than 1.90 k

Ω. The ID_GND bit

in the Status register indicates whether the ID pin is shorted

to ground or not. If the ID pin is shorted to ground with less

than 30

Ω of resistance, the ID_GND pin is set to “1”.

Table 6. ADC Output vs. Resistor Values (Unit: k

Ω)

ADC Result

RID (kΩ)

ADC Result

RID (kΩ)

ADC Result

RID (kΩ)

ADC Result

RID (kΩ)

00000

(1)

01000

10.03

10000

40.2

11000

255

00001

2.00

01001

12.03

10001

49.9

11001

301

00010

2.604

01010

14.46

10010

64.9

11010

365

00011

3.208

01011

17.26

10011

80.6

11011

442

00100

4.014

01100

20.5

10100

102

11100

523

00101

4.820

01101

24.07

10101

121

11101

619

00110

6.03

01110

28.7

10110

150

11110

1000

00111

8.03

01111

34.0

10111

200

11111

(2)

Notes

If the ID resistance is below 1.90 k

Ω (nominal value), the ADC result is set to 00000.

If the ID line is floating, the ADC result is set to 11111

POWER SUPPLY TYPE IDENTIFICATION

The 34825 supports various standard power supplies for

charging the battery. The power supplies supported include

those that are user defined, and the ones 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.

The five types of power supplies specified in the afore

mentioned two specification documents are listed in Table 7.

The Power Supply Type Identification (PSTI) function is

offered to assist the identification of the power supply type.

The PSTI state machine checks the connection status

between the DP and the DM pins. The state machine starts

when the VBUS pin voltage rises above the VBUS detection

threshold, which is indicated with an VBUS_DET bit in the

status register. The state machine will find out if the DP and

DM pins are shorted, indicated with the DP/DM_SHORT bit,

or the connection has the characteristics of a USB charger,

indicated with the USB_CHG bit. Together with the ID

detection result, the power supply type can be determined.

The conditions for reaching the conclusion of the five

supported power supplies are listed in Table 7.

Table 7. Power Supply Type vs. Detection Result

Item #

VBUS_DET

DP/DM_SHORT

USB_CHG

ID_FLOAT

ADC Result

Accessory Type

11111

Standard USB Port

11111

USB Charger

11111

Dedicated Charger

10111

Carkit Charger Type 1

11011

Carkit Charger Type 2

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