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 1.5 A at 3.3 V (5 W). Keep in mind that operating at a lower voltage requires higher current capability from the power supply to achieve the 5 W requirement.
  3. Place sufficient bulk capacitance on the XBee VCC pin to maintain voltage above the minimum specification during inrush current. Inrush current for VCC = 3.3 V is about 2 A during initial power up of cellular communications and wakeup from sleep mode. We recommend a minimum of 220 µF of capacitance on the VCC pin.
  4. Place a 10 nF ceramic capacitor very close to the XBee Cellular 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).

  6. If you use DO (Device Options) to enable 2G fallback mode, the power supply must be capable of supplying 11.5 W and the minimum input voltage is 3.8 V (for example 3.0 A @ 3.8 V). In addition, we recommend 1000 µF of bulk capacitance on the VCC pin. The supply should never drop below 3.6 V during TX bursts.