Power Supply Considerations; Add A Capacitor To The Reset Line - Digi XBee Cellular LTE Cat 1 User Manual

Hardware
The results may vary by implementation and scenario. You should always perform sufficient testing to
ensure that the XBee Cellular Modem does not exceed temperature specifications.
Scenario
Maximum
current
50% current
20% current
Device available
Sleep current
scenario—high
latency

Power supply considerations

When considering a power supply, use the following design practices.
1. Keep power supply ripple below 75 mV.
2. The supply should handle 1.5 A.
3. Place sufficient bulk capacitance on the VCC to maintain voltage above the minimum
specification during inrush current. Inrush current is about 2 A during initial power up of cellular
communications and during cellular restart conditions.
4. Place smaller high frequency ceramic capacitors very close to the XBee Cellular Modem VCC
pin to decrease high frequency noise.
5. The power supply trace must be thick enough to handle the current requirements with minimal
voltage drop when peak currents are reached. Lower voltages require more current to achieve
the same power output. Supply voltage steady state at VCC pin 1 should change by less than
0.1 V if drawing 0.5 W compared to drawing 2.8 W.

Add a capacitor to the RESET line

In high EMI noise environments, we recommend adding a 10 nF ceramic capacitor very close to pin 5.
1
NR = not recommended.
Digi XBee Cellular LTE Cat 1 Embedded Modem User Guide
3.3 V
average
current Scenario example
950 mA Running video camera
475 mA Running low-resolution
camera
200 mA Sending 2 MB picture of
traffic every minute
170 mA Updating traffic sign
20 mA Wakes at most once per
hour to send and/or
receive data

Power supply considerations

Maximum ambient
temperature
Peak MB No
consumed heat Heat
per hour sink sink
1
200 to 2000 NR 31 °C 70 °C
80 to 500 42 °C 55 °C 75 °C
10 to 100 64 °C 70 °C 78 °C
1 to 10 66 °C 71 °C 78 °C
Less than 0.1 78 °C 78 °C 78 °C
Heat
sink
and fan
36