Power Saving; Sleep Mode; Airplane Mode; Power Supply - Quectel EC21 Mini PCIe Series Hardware Design

3.2. Power Saving

3.2.1. Sleep Mode

EC21 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.

Ensure the 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.

3.2.2. 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, please refer to Chapter 3.10.3.

3.3. Power Supply

The following table shows pin definition of VCC_3V3 pins and ground pins.
Table 6: Pin Definition of VCC_3V3 and GND Pins
Pin Name Pin No.
VCC_3V3 2, 39, 41, 52
4, 9, 15, 18, 21,
GND 26, 27, 29, 34, 35,
37, 40, 43, 50
The typical supply voltage of EC21 Mini PCIe is 3.3V. In the 2G network, the input peak current may reach
2.7A during the transmitting time. Therefore, the power supply must be able to provide a rated output
current of 2.7A at least, and a bypass capacitor of no less than 470µF 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.
EC21_Mini_PCIe_Hardware_Design
I/O Power Domain
PI 3.0V~3.6V
LTE Standard Module Series
EC21 Mini PCIe Hardware Design
Description
Typically 3.3V DC supply
Mini card ground
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