34825 Datasheet, PDF (20/39 Pages) Freescale Semiconductor, Inc – Micro-USB Interface IC Supporting Universal Charging Solution and Wired Accessories

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 kΩ. 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: kΩ)
ADC Result
00000
00001
00010
00011
00100
00101
00110
00111
R_ID (kΩ)
(1)
2.00
2.604
3.208
4.014
4.820
6.03
8.03
ADC Result
01000
01001
01010
01011
01100
01101
01110
01111
R_ID (kΩ)
10.03
12.03
14.46
17.26
20.5
24.07
28.7
34.0
ADC Result
10000
10001
10010
10011
10100
10101
10110
10111
R_ID (kΩ)
40.2
49.9
64.9
80.6
102
121
150
200
Notes
1. If the ID resistance is below 1.90 kΩ (nominal value), the ADC result is set to 00000.
2. If the ID line is floating, the ADC result is set to 11111
ADC Result
11000
11001
11010
11011
11100
11101
11110
11111
R_ID (kΩ)
255
301
365
442
523
619
1000
(2)
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
Table 7. Power Supply Type vs. Detection Result
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.
Item #
VBUS_DET DP/DM_SHORT
USB_CHG
ID_FLOAT
ADC Result
Accessory Type
1
1
0
0
1
11111
Standard USB Port
2
1
0
1
1
11111
USB Charger
3
1
1
0
1
11111
Dedicated Charger
4
1
1
0
0
10111
Carkit Charger Type 1
5
1
1
0
0
11011
Carkit Charger Type 2
34825
20
Analog Integrated Circuit Device Data
Freescale Semiconductor