Using RF Module with Switching Power Supply

The now End-Of-Lifed Digi XStream, XCite, and the current 9XTend modules require a regulated 5V DC supply. The Digi XBee modules require a 3V regulated power supply.

Switching supplies may be used, though special care must be taken to ensure optimum performance, as noise on the power supply can affect the operation of the radio.

Most step-up and step-down switching supplies, and even some RS232 level converters, can introduce ripple into the power supply. The magnitude of this ripple must fall within the radio modem specification of +/-0.25V as per the manual.

XBee Modules

For the XBee modules, we recommend keeping the supply voltage within the module's VCC specifications. To help reduce noise, we recommend placing a 1.0 µF and 8.2 pF capacitor as near as possible to the VCC connection on the XBee 3 RF Module (pad 2 for micro and surface-mount, and pin 1 for through-hole). Adding a 10 µF decoupling capacitor is also recommended. If you are using a switching regulator for the power supply, switch the frequencies above 500 kHz. Limit the power supply ripple to a maximum of 50 mV peak-to-peak. For best results, place the lower capacitance capacitors closest to the XBee 3 RF Module.

For the XStream, XCite, and Xtend modules, care must be taken to ensure that the frequency components of the ripple do not affect the radio performance. Frequency components between 20 kHz and 100 kHz are particularly harmful to the performance of the radio. A simple L-C low-pass filter should be used to block the switching noise that otherwise may reduce the performance of the radio module.

Ask a Digi Support Representative for additional help with this if necessary.

Last updated: Aug 08, 2017

Filed Under

GatewaysRFRF Dev kits

Recently Viewed

No recently viewed articles

Did you find this article helpful?