NB-IoT Module Series
BC66 Hardware Design
BC66_Hardware_Design 31 / 50
Keep placement of USIM card connector as close as possible to the module. Keep the trace length
as less than 200mm as possible.
Keep USIM card signals away from RF and VBAT traces.
Assure the ground between the module and the USIM card connector short and wide. Keep the trace
width of ground no less than 0.5mm to maintain the same electric potential. The decouple capacitor
between SIM_VDD and GND should be not more than
1μF and be placed close to the USIM card
connector.
To avoid cross talk between SIM_DATA and SIM_CLK, keep them away from each other and shield
them separately with surrounded ground.
In order to offer good ESD protection, it is recommended to add a TVS diode array. For more
information of TVS diode, please visit http://www.onsemi.com. The ESD protection device should be
placed as close to USIM card connector as possible, and make sure the USIM card signal lines go
through the ESD protection device first and then to the module.
The 22Ω resistors should be
connected in series between the module and the USIM card connector so as to suppress EMI
spurious transmission and enhance ESD protection. Please note that the USIM peripheral circuit
should be close to the USIM card connector.
Place the RF bypass capacitors (33pF) close to the USIM card connector on all signal traces to
improve EMI suppression.
3.11. ADC Interface*
The module provides a 10-bit ADC input channel to read the voltage value. The interface is available in
both active and idle modes.
Table 12: Pin Definition of ADC Interface
“*” means under development.
3.12. RI Behaviors*
When there is a SMS or URC output, the module will inform DTE with the RI pin. More details will be
added in the future version of this document.
Pin Name
Pin No.
Description
ADC0*
9
Analog to digital converter interface
NOTE
