Product Info

LTE Standard Module Series
EC21_Series_Mini_PCIe_Hardware_Design
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3.4. Power Saving
3.4.1. Sleep Mode
EC21 series Mini PCIe is able to reduce its current consumption to a minimum value in sleep mode.
There are three preconditions must be met to make the module enter sleep mode.
 Execute AT+QSCLK=1 to enable sleep mode. For more details, see document [1].
 Ensure DTR is kept at high level or be kept open.
 The host’s USB bus, which is connected with the module’s USB interface, enters suspend state.
3.4.2. Airplane Mode
When the module enters airplane mode, the RF function will be disabled, and all AT commands related
to it will be inaccessible. For more details, refer to Chapter 3.10.3.
3.5. Power Supply
The following table shows pin definition of VCC_3V3 pins and ground pins.
Table 7: Pin Definition of VCC_3V3 and GND Pins
The typical supply voltage of EC21 series Mini PCIe is 3.3 V. In the 2G network, the input peak current
may reach 2.7 A during the transmitting time. Therefore, the power supply must be able to provide a
rated output current of 2.7 A at least, and a bypass capacitor of no less than 470 µF with low ESR should
be used to prevent the voltage from dropping. If the switching power supply is used to supply power to
the module, the power device and power supply routing traces of the switching power supply should
avoid the antennas as much as possible to prevent EMI interference.
The following figure shows a reference design of power supply where R2 and R3 are 1 % tolerance
resistors and C3 is a low-ESR capacitor (470 µF).
Pin Name Pin No. I/O Power Domain Description
VCC_3V3 2, 39, 41, 52 PI 3.0–3.6 V Typ. 3.3 V DC supply
GND 4, 9, 15, 18, 21, 26, 27, 29, 34, 35, 37, 40, 43, 50