User's Manual

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4）The USB interface input the voltage from USB_IN .For keeping the USB in U6300 module working unfailingly, a
voltage protection circuit should be added by user between the USB_IN of USB interface and the USB_VBUS PIN of
U6300. It is shown in figure 2-8 with the red circle 2. In the voltage protection circuit, D603 is a Zener diode with a
breakdown voltage value of 5.1v which could keep the voltage on the USB_VBUS PIN of U6300 not more than
5.1v. D602 is a Schottky Diode, and R621 is a resistor with the value 1KΩ. On the other hand the voltage coming
from the USB_IN also could be converted by using a DC/DC converter to 3.6v and then be sent to VBAT PIN of
U6300. It is shown in figure 2-8 with the red circle 1.
Figure2-8 The reference of voltage protection circuit
2.2.4 USIM interface
U6300 supports GSM850/GSM900/DCS1800/PCS1900 and UMTS2100/UMTS1900/UMTS850 operation mode. The
UMTS mode submits to 3GPP R99（2002.9）criterion，and the GSM/GPRS/EDGE mode submits to CMCC GSM/GPRS
criterion. USIM card as well as SIM card can be used.
2.2.4.1 Description
U6300 offers USIM card interface by Mini PCIe Interface. And it can be used in both UMTS and GSM/GPRS/EDGE
networks. The table 2.5 gives the more detail information.
Table 2.5 U6300 USIM card interface description
Signals offered The name of the correlative SN. of the Mini PCIe Description