Datasheet

Analog Integrated Circuit Device Data
101 Freescale Semiconductor
MC34708
Functional Block Description
7.8.4.14 5-Wire Charger or A/V Charger Mode
When the attached accessory is a 5-Wire Charger or A/V Charger, the MC34708 enables the appropriate device type 5.0 W CHG
or A/V in the USB device type register.
The VBUS detector is used to monitor the detachment of the charger. The falling edge of USBDETS is an indication of the charger
detachment. Both unplugging the mini-USB connector and unplugging the ac side lead to the same detachment conclusion. The
Detach bit is set to inform the host. Then the MC34708 USB detection enters the Standby mode.
7.8.4.15 Device Detect Mode
When the Manual SW_B bit is set to 1, the MC34708 automatically detects what device is attached.
7.8.4.16 Unknown Accessory Operation Mode
When an unknown accessory is attached, the ID_FLOAT bit is cleared or the USBDETS bit is set to '1'. Only the Unknown_Atta
bit is set to interrupt the baseband. The Attach bit is not set to distinguish the unknown accessory from the known accessory. No
other actions are taken.The falling edge of the USBDETS or the rising edge of the ID_FLOAT signals can trigger the detachment
detection. The Detach bit is set to inform the detachment of the unknown accessory. The USB detection then enters the Standby
mode.
7.8.4.17 Software Reset
The USB detection supports a software reset, which is realized by writing the Reset bit in the USB Control register to 1. The
consequence of the software reset is the same as the hardware reset. All register bits reset by the Mini-USB will be reset.
7.8.4.18 ID Resistance Value Assignment
The ID resistors used are standard 1% resistors. Table 95 lists the complete 32 ID resistor assignment. Those with the Assigned
Functions filled are ones already used with special functions. The ones reserved can be assigned to other functions.
Table 94. ID Detection Thresholds
UID Pin External
Connection
UID Pin Voltage
(70)
IDFLOATS IDGNDS IDFACTORYS Accessory
Resistor to Ground 0.18 * VCORE < UID < 0.77 * VCORE
0 1 0
Non-USB accessory is attached (per
CEA-936-A spec)
Grounded 0 < UID < 0.12 * VCORE
0 0 0
A type plug (USB default slave) is
attached (per CEA-936-A spec)
Floating 0.89 * VCORE < UID < VCORE
1 1 0
B type plug (USB Host, OTG default
master or no device) is attached.
Voltage Applied 3.6 V < UID (1)
1 1 1
Factory mode
Notes
70. UID maximum voltage is 5.25 V
Table 95. ID Resistance Assignment
Item# ADC Result ID Resistance K Assignment
0 00000 <1.9 Reserved
1 00001 2.0 S0
2 00010 2.604 S1
3 00011 3.208 S2
4 00100 4.014 S3