User's Manual

UMTS/HSDPA Module Series
UC15 Hardware Design
UC15_Hardware_Design Confidential / Released 28 / 78
 AT+CFUN=4: Disable RF function (airplane mode). All AT commands related to RF function are not
accessible.
For detailed information about command AT+CFUN, please refer to document [1].
3.6. Power Supply
3.6.1. Power Supply Pins
UC15 provides four VBAT pins to connect with the external power supply. There are two separate voltage
domains for VBAT.
 VBAT_RF with two pads for module RF.
 VBAT_BB with two pads for module baseband.
The following table shows the VBAT pins and ground pins.
Table 6: VBAT and GND Pin
3.6.2. Decrease Voltage Drop
The power supply range of the module is 3.3~4.3V. Because of the voltage drop during the transmitting
time, a bypass capacitor of about 100µF with low ESR should be used. Multi-layer ceramic chip (MLCC)
capacitor can provide the best combination of low ESR. Three ceramic capacitors (100nF, 33pF, 10pF)
are recommended to be applied to the VBAT pins. The capacitors should be placed close to the VBAT
pins of UC15. The following figure shows star structure of the power supply.
The main power supply from an external application should be a single voltage source and has to be
expanded to two sub paths with star structure. In addition, in order to get a stable power source, it is
suggested to use a zener diode of which reverse zener voltage is 5.1V and dissipation power is more than
0.5W.
Pin Name Pin No. Description Min. Typ. Max. Unit
VBAT_RF 50,51 Power supply for module RF. 3.3 3.8 4.3 V
VBAT_BB 52,53
Power supply for module
baseband.
3.3 3.8 4.3 V
GND
42,44~49,65,
67~68,81~108
Ground. - - - -