Product Info

LTE Standard Module Series
EC25 Series Hardware Design
EC25_Series_Hardware_Design 63 / 134
⚫ It is important to route the SDIO signal traces with total grounding. The impedance of SDIO signal
trace is 50 Ω ±10%.
⚫ Keep SDIO signals far away from other sensitive circuits/signals such as RF circuits, analog signals,
etc., as well as noisy signals such as clock signals, DC-DC signals, etc.
⚫ It is recommended to keep matching length between CLK and DATA/CMD less than 1 mm and total
routing length less than 50 mm.
⚫ Keep termination resistors within 15–24 Ω on clock lines near the module and keep the route
distance from the module clock pins to termination resistors less than 5 mm.
⚫ Make sure the adjacent trace spacing is 2 times of the trace width and bus capacitance is less than
15 pF.
3.14.2. BT Interface
EC25 supports a dedicated UART interface and a PCM interface for BT application.
BT UART interface supports high-speed UART operation up to 3 Mbps. It also supports RTS and CTS
hardware flow control.
As UART signals are very high-speed, in order to ensure the BT UART interface works normal, please
comply with the following principles:
⚫ The module provides 1.8 V BT UART interface. A level translator should be used if customers’
application is equipped with a 3.3 V UART interface. Make sure the level translator support high rate
data transmission.
⚫ Make sure the communication cable support high rate data transmission.
3.15. ADC Interfaces
The module provides two analog-to-digital converter (ADC) interfaces. AT+QADC=0 command can be
used to read the voltage value on ADC0 pin. AT+QADC=1 command can be used to read the voltage
value on ADC1 pin. For more details about these AT commands, please refer to document [2].
In order to improve the accuracy of ADC, the trace of ADC should be surrounded by ground.
Table 17: Pin Definition of ADC Interfaces
Pin Name
Pin No.
Description
ADC0
45
General-purpose analog to digital converter