Design recommendations
Power supply considerations
Digi XBee3 Cellular LTE-M Global Smart Modem User Guide
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Power supply considerations
When considering a power supply, use the following design practices.
1. Power supply ripple should be less than 75 mV peak to peak.
2. The power supply should be capable of providing a minimum of 750 mA at 3.3 V (2.5 W).
3. Place sufficient bulk capacitance on the XBee VCC pin to maintain voltage above the minimum
specification during transmissions.
lists the peak current during
transmitting.
4. Place smaller high frequency ceramic capacitors very close to the XBee Smart Modem VCC pin
to decrease high frequency noise.
5. Use a wide power supply trace or power plane to ensure it can handle the peak current
requirements with minimal voltage drop. We recommend that the power supply and trace be
designed such that the voltage at the XBee VCC pin does not vary by more than 0.1 V between
light load (~0.5 W) and heavy load (~3 W). The supply should be inside the supply voltage
operating range at startup and should not be allowed to droop lower than 3.2 V during
operation.
Minimum connection diagram
In high EMI noise environments, we recommend adding a 10 nF ceramic capacitor very close to pin 5.
Heat considerations and testing
The XBee Smart Modem may generate significant heat during sustained operation. In addition to
heavy data transfer, other factors that can contribute to heating include ambient temperature, air
flow around the device, and proximity to the nearest cellular tower (the XBee Smart Modem must
transmit at a higher power level when communicating over long distances). Overheating can cause
device malfunction and potential damage. In order to avoid this it is important to consider the
application the XBee Smart Modem is going into and mitigate heat issues if necessary.
We recommend that you perform thermal testing in your application to determine the resulting
steady state temperature of the XBee Smart Modem. Use
to estimate the device