In this guide
No, you cannot reliably charge a single device using both Micro USB and USB-C ports at the same time. Most devices prioritize one port — usually USB-C — and disable the other due to power negotiation conflicts.
- You use a specialized splitter cable (USB-C to dual Micro USB) drawing basic 5V power from one source
- Your Micro USB device uses an OTG adapter with a 100kΩ bridging resistor for charge-through
- Your device has dual input ports (e.g., a power bank) — simultaneous input is blocked to prevent damage
- USB-C Power Delivery conflicts with the Micro USB 5V profile, causing one port to shut off
- Standard off-the-shelf cables or adapters are used — they lack bridging resistors and trigger host mode
Why Simultaneous Charging Usually Fails
When a device detects power on its USB-C port, it begins a handshake process to negotiate voltage and current. Micro USB operates on a simpler 5V-only profile with no negotiation. If both ports receive power at the same time, the device firmware typically picks one source and actively rejects the other to avoid a conflict between the two incompatible power profiles.
On dual-input power banks, the hardware itself prevents simultaneous input charging. Manufacturers block it to protect battery cells and charging circuits from receiving uncontrolled current from two directions at once.
The One Setup That Can Work
A specialized splitter cable — such as a USB-C to dual Micro USB — can feed basic 5V charging to two Micro USB devices from a single power source. This is not true simultaneous dual-port charging on one device; it splits power across two separate devices. No Power Delivery, no fast charge, and no data transfer are supported in this configuration.
For Micro USB devices that need to run accessories and charge at the same time, an OTG adapter with the correct 100kΩ ID-pin resistor can enable charge-through. Without that resistor, the port switches to host mode and charging stops entirely.
Quick Reference: Common Setups
| Setup | Works? | Need | Note |
|---|---|---|---|
| USB-C + Micro USB on same device | No | — | Port conflict; firmware disables one |
| Dual-input power bank charged from both ports | No | — | Hardware blocked by design |
| Splitter cable to two Micro USB devices | Yes | Splitter cable | 5V only, no PD or fast charge |
| Micro USB OTG with charge-through | Yes | OTG adapter with 100kΩ resistor | Accessory + charge simultaneously |
USB-C and Charging Standards
USB-C’s power negotiation is defined by the USB Battery Charging 2.0 specification from USB-IF, which outlines how ports detect, negotiate, and deliver charge. Micro USB predates this spec and has no equivalent handshake, which is the root cause of the incompatibility when both are active at once.
If you are working with USB-C video or display alongside charging, see our guide on whether USB-C can connect to HDMI and what to do when USB-C to HDMI is not working to avoid similar port conflict issues.
Bottom line: Charging with Micro USB and USB-C at the same time on a single device is not reliably possible with standard cables. Stick to USB-C alone for the fastest, most stable charge — or use a purpose-built splitter only when feeding two separate Micro USB devices from one 5V source.