FAQ - Frequently Asked Questions - Power design for wireless modules: what engineers should check
Intro
Wireless modules can draw short, high current peaks during transmission. If the power supply is not designed for these peaks, the module may reset, disconnect or fail to register on the network.
This is especially important for cellular, Wi-Fi and high-power radio modules.
Key technical selection criteria
Evaluate:
- module peak current
- average current
- supply voltage tolerance
- regulator transient response
- capacitor placement
- PCB trace width
- battery internal resistance
- low-temperature behaviour
- power sequencing
- RF transmit conditions
Peak current behaviour
Do not design only for average current.
Check:
- transmit burst current
- network registration current
- poor signal conditions
- retry behaviour
- firmware update current
- simultaneous sensor or processor load
Capacitor placement
Place bulk and decoupling capacitors close to the module supply pins.
Review:
- capacitance value
- ESR
- voltage rating
- temperature behaviour
- distance to module
- ground connection
- current loop area
Battery-powered designs
Battery impedance can cause voltage dips during transmission.
Check:
- battery chemistry
- state of charge
- low-temperature performance
- pulse current capability
- connector resistance
- protection circuit behaviour
Common mistakes
- powering the module from a weak rail
- ignoring transmit peaks
- placing capacitors too far away
- using thin supply traces
- not testing under poor signal conditions
- ignoring low-temperature battery behaviour
- not checking startup sequence
Decision checklist
Before finalising the design, check:
- peak current rating
- regulator response
- capacitor placement
- PCB trace width
- supply voltage drop
- battery pulse capability
- startup sequence
- test results during real network activity
Need help reviewing the power design for a wireless module? Contact TOP-electronics technical support.
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