Abstract

Multiple devices charging together is common; a USB charger uses dedicated ICs to manage total output. The USB charger builds a shared power pool and redistributes power by device demand. Total power limit, priority and scheduling of the USB charger define multi-port performance.

1. Shared Power Pool Bound

A multi-port USB charger has a fixed total rating, and sum of all outputs cannot exceed this value. The pool prevents the USB charger from overload when many loads connect. Confirm total wattage of the USB charger before calculating combined device consumption.

2. Port Priority Rules

Some USB charger models mark priority ports which get fast-charge power first, while other ports stay at 5V. Priority keeps key devices of the USB charger fast-charged and secondary devices trickle charged. Custom priority logic can be programmed into a USB charger.

3. Load Detection and Polling

A USB charger polls ports continuously, detects handshake requests and reallocates power in real time. Fast polling enables smooth power transition of the USB charger during plug and unplug cycles. Test a USB charger with repeated device swaps to avoid allocation lag.

4. Power Fold-Back Protection

When combined draw exceeds rating, the USB charger reduces per-port power to stay safe. Fold-back prevents hard overcurrent shutdown of the USB charger. Tune scheduling algorithms of the USB charger to balance speed and stability.

Conclusion

For multi-device charging, dynamic sharing of the USB charger stabilizes every channel. Check power pool limits, priority, polling detection and fold-back behavior of the USB charger. Need multi-port hardware with custom power scheduling firmware? Contact Simsukian for custom firmware development.。This USB charger can be customized in specifications according to your project application scenarios.

References

1. USB Power Delivery Multi-Port Guidelines

2. IEC 62368-1 Audio/video and ICT safety

3. DOE External Power Supply Test Procedures