NB-IoT against LTE-M When the Device Crosses Borders
NB-IoT offers superior signal penetration and lower single-mode hardware costs, but LTE-M delivers seamless global cross-border roaming and continuous mobility.
Milliamp Peak Transmit Current
Meaning
Maximum current measurements determine the peak electrical power drawn from the supply during cellular radio transmission bursts. The milliamp peak transmit current is the highest current drawn by the transmitter during a packet transmission, and it can exceed several hundred milliamps for brief periods. This parameter is used to design the device’s power supply and does not represent average energy consumption.
Power Supply
The power delivery network must be capable of delivering these high-current pulses without failing. If the power supply is too weak, the output voltage will drop, which can cause the device to reset or the radio to malfunction. Designers must select voltage regulators and batteries that are rated to handle these peak currents safely.
Voltage Sag
Rapid surges in current draw create a voltage drop across the internal resistance of the battery and power lines. This sag can be mitigated by keeping the circuit traces short and wide to minimize electrical resistance. It also requires careful layout of the power rails to isolate sensitive circuits from the noise generated by the transmitter.
Capacitor Selection
Large storage capacitors are placed close to the transmitter to supply the sudden bursts of current. These capacitors act as a buffer, preventing the voltage from dropping during transmission. Their selection depends on the peak current duration and the allowed voltage sag.