Quick Answer: This adapter presents a USB-C socket to a host and a Micro-B plug to a legacy device, so it carries 5 V and USB 2.0 data at 480 Mbit/s, nothing more. Expect 500 mA to 1.5 A at 5 V depending on the device’s own limit, never 9 V or 20 V, and never video. The build detail that decides whether it works at all is the 56 kOhm pull-up on the CC pin: without it a USB-C charger sees an open port, supplies no output and the device stays dead.
The connector on the device is the constraint, not the connector on the cable. A Micro-B receptacle is a USB 2.0 part with five contacts and a 1.8 A contact rating, so an adapter that puts a USB-C socket in front of it cannot create power delivery, SuperSpeed lanes or an alternate mode. What it can do is let a modern charger and a modern cable reach an older device.
What the adapter actually changes
Mechanically it converts a USB-C cable end into a Micro-B plug. Electrically it passes VBUS, earth, D+ and D- straight through, and terminates the two CC contacts through a single 56 kOhm resistor to VBUS, which advertises a legacy adapter to the charger. No e-marker, no SuperSpeed pairs, no sideband: four useful conductors out of the twenty-four in a USB-C plug. That is why the adapter is short and cheap; anything longer would be pretending.
Current and charging behaviour
Why a charger may refuse to start
A USB-C source only applies 5 V after it detects a sink through the CC pin. Adapters built without the resistor, or with it on the wrong pin, look like an open circuit: the charger stays at 0 V and the device shows no sign of life. If a known charger works with a USB-A cable and fails through the adapter, the resistor is missing.
What current to expect
The 56 kOhm termination requests default USB power, which is 500 mA for a USB 2.0 host and up to 1.5 A at 5 V when the source supports Battery Charging 1.2. In practice the Micro-B contact rating and the device’s charge controller set the real figure, usually 0.5-1.8 A. Charging a 3,000 mAh phone battery at 1 A takes about three hours; the same phone on a native USB-C port at 15 W takes under an hour.
Data, OTG and direction
Data runs at 480 Mbit/s, about 40 MB/s of payload, and the adapter is not directional in the way people assume: the host must be the USB-C side. Feeding a Micro-B port from a USB-C charger is the common use; connecting two computers through it will not work, because both ends would be hosts. A Micro-B device that expects an ID pin for OTG sees it floating and behaves as a plain peripheral. If the target device uses Mini-B instead, the connectors are not interchangeable, as covered in the micro usb and connector notes.
Functions compared
| Function | Result | Figure | Limit |
|---|
| Charging at 5 V | Works | 0.5-1.5 A | Contact rating |
| USB 2.0 data | Works | 480 Mbit/s | Four conductors only |
| USB Power Delivery | Fails | 5 V fixed | No e-marker |
| SuperSpeed data | Fails | n/a | No high speed pairs |
| Video over USB-C | Fails | n/a | No alternate mode |
Practical scenarios
- Situation: A field team carries USB-C chargers and one legacy barcode scanner with a Micro-B port. Fit the adapter on the device and leave it there, which saves the Micro-B socket from 20 insertions a day.
- Situation: A receipt printer at a counter is fed from a USB-C charger through the adapter. Check the draw first: 0.9 A at 5 V (4.5 W) is within the 1.5 A ceiling, but a printer that peaks at 2 A will brown out on the first job.
- Situation: A dash camera charges at 1 A and records to a card over the same port. The 480 Mbit/s link is ample for card access, so the adapter works, but the cable must be rated for 2 A or the port voltage sags to 4.6 V.
- Situation: A workshop wants to test a Micro-B device from a USB-C laptop. Plug the adapter into the device and a USB-C data cable into the laptop; use the micro usb for printer lead pattern of plug-then-power to avoid enumeration errors.
Recommendation and failure symptoms
Buy an adapter that states the 56 kOhm CC termination and a 1.5 A contact rating, and treat it as a charging and USB 2.0 part. It is the right answer for a legacy device that must survive another two years on a modern charger, and the wrong answer for anything that needs speed. Symptoms map cleanly: no response at all means no CC termination; a device that charges only when the cable is flipped means one CC pin is unconnected; a slow charge with a warm plug means contact resistance in the Micro-B shell; data that drops when a nearby motor starts means an unshielded moulding.
Where the aim is a permanent 15 W feed, a proper usb type c port for charging wired to the device is a better answer than an adapter stack, because it removes the 1.5 A bottleneck entirely.
FAQ
Will this converter fast charge a phone?
Only at 5 V. Without an e-marker there is no Power Delivery negotiation, so the charger stays at its default 5 V output and the phone draws 0.5-1.5 A. That is 2.5-7.5 W, well short of a native USB-C fast charge.
Can it connect a USB-C laptop to a Micro-B hard drive?
Yes, if the drive is USB 2.0 and self-powered or low draw. It will appear as a 480 Mbit/s device, roughly 40 MB/s, and a 2.5 inch drive that needs 900 mA may not spin up from a laptop port through the added contact resistance.
Why does nothing happen when it is plugged in?
The charger is not detecting a sink. Either the CC resistor is missing or the adapter is inserted into a USB-C port that expects a device rather than a source. Test the same adapter on a USB-A charger with an A-to-C cable to confirm.
