
Analog Integrated Circuit Device Data
Freescale Semiconductor
119
PC34708
Functional Block Requirements and Behaviors
Mini/Micro USB Interface Description and Application Information
The VBUS detector is used to monitor the detachment of the charger. The falling edge of USBDETS is an indication of charger
detachment. Unplugging the mini-USB connector and unplugging the ac side, both lead to the same detachment conclusion. The
Detach bit is set to inform the host. The PC34708 USB detection then enters the Standby mode.
7.10.15 5-Wire Charger or A/V Charger Mode
When the attached accessory is a 5-Wire Charger or A/V Charger, the PC34708 turns on the MVBUS switch, to allow the charger
to start, configures the input current limit to the charger (500 mA), and sets 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 PC34708 USB detection enters the Standby mode.
7.10.16 Charger Input Current Limit Setting
When the Manual SW_B bit is set to 1, the PC34708 automatically detects what device is attached, and configures the charger
input current by setting the USBCHGRG[1:0] signals (these are internal signals and not SPI bits). There is an option of overriding
the automatic detection thresholds, by setting the SPI bit Manual SW_B low, and then the charger input current limit can be
programmed via the MUSBCHRG[1:0] SPI bits in the USB Control register.
7.10.17 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. If an unknown powered accessory is attached, the switch MVBUS is turned on during the identification
process, and the switch MVBUS will be turned off immediately when the accessory is identified as an unknown accessory.
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.
7.10.18 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.
Table 116. Charger Input Current Limit Settings
USBCHRG[1:0] (Internal Signal)
MUSBCHRG[1:0]
Charger input
Current Limit (mA)
Device type detected in
Auto mode
00
Disable Charger
01
100
USB Host
10
500
5-Wire, AV charger, USB JIG
11
950
USB Charger, Dedicated
charger, Factory mode
Table 117. ID Detection Thresholds
UID Pin External
Connection
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
A type plug (USB default slave) is
attached (per CEA-936-A spec)