Contents:

USB Mini connectors

Keyed connectors x ID pin

Charging

Abuse of pin 4

Connector variants

USB Mini-A plug (deprecated)

Pinout

Compatible with

USB Mini-B plug

Pinout (client)

Pinout (OTG host)

Compatible with

USB Mini-AB receptacle (deprecated)

Pinout

Compatible with

USB Mini-A receptacle (abandoned)

Pinout

Compatible with

USB Mini-B receptacle

Pinout (client)

Pinout (OTG host)

Pinout for (OTG host+client)

Compatible with

Related: My USB adapters

USB Mini connectors

USB Mini connectors were introduced as Engineering Change Notice to the USB 2.0 standard and removed from the USB 3.0 specification in favor of Micro-USB.

But these connectors are still very popular and people and even resellers are confused by the connector variants.

Keyed connectors x ID pin

The later USB Mini mechanical specification defined “keyed” connectors with different shape of the host and client sides. But these newly introduced Mini-AB and Mini-A connectors never reached mass deployment and now they are deprecated in favor of USB-OTG. Most manufacturers use only the Mini-B connectors nowadays (it even seems that Mini-A and Mini-AB connectors are no more in production). Host/client switching is done via the USB OTG logic:

Host devices should connect power to pin 5 only if they detect host cable.

Charging

The correct charging protocol should use USB handshaking. Device should provide two device profiles:

Client and host should do USB power budget handshaking and decide whether the client device should be charged (e. g. connection of a desktop computer to a camera should turn charging on, connection of PDA host to the same camera should not turn charging on). Most manufacturers make their life easier and don't implement USB power budget handshaking before they start to charge. Hopefully, even more host device manufacturers don't implement USB power budget handshaking and always allow maximal current on the pin 1.

So even if charged device does no USB power budget handshaking (and even no USB communication at all) and specification says that charging should not work, the real life is easier and nearly all devices are charged correctly.

Please note that chargers use a non-standard USB wiring:

USB standard does not allow use of USB Mini for charging of devices that support both host and client modes. That prevents short circuits between power lines on pin 1 and potential damage of the device.

Abuse of pin 4

As pin 4 is not used on clients, manufacturers often abuse it. It may provide audio or video signal, extra power, charging etc. Be aware that devices that abuse pin 4 may be damaged by using of a cable that abuses pin 4 in a different way.

Connector variants

USB Mini-A plug (deprecated)

USB Mini-A plug

Connects clients to a host device. Now it is deprecated in favor of USB-OTG. It is physically incompatible with modern USB Mini-OTG hosts!

Designated color: white

Pinout:

  1. Vcc
  2. D-
  3. D+
  4. connect with pin 5
  5. GND

Compatible with:

  • USB Mini-AB receptacle (pre-OTG host)
  • USB Mini-A receptacle (pre-OTG host)

USB Mini-B plug

USB Mini-B plug

It connects to the client device and host devices that support OTG. It's one of the most common connectors. After introduction of OTG it is sometimes called as USB Mini-C.

Designated color: black

Pinout (client):

  1. Vcc
  2. D-
  3. D+
  4. unused
  5. GND

Pinout (OTG host):

  1. Vcc
  2. D-
  3. D+
  4. connect with pin 5
  5. GND

Compatible with:

  • USB Mini-B receptacle (OTG host (optional), OTG client (optional), pre-OTG client)
  • USB Mini-AB receptacle (pre-OTG host, pre-OTG client)

USB Mini-AB receptacle (deprecated)

USB Mini-AB receptacle

Older receptacle capable of both host and client mode. If the ID pin is grounded by the cable, device should switch to the host mode. Now it is deprecated in favor of USB-OTG.

Designated color: gray

Pinout:

  1. Vcc/optional client voltage detection
  2. D-
  3. D+
  4. ID (host cable identification)
  5. GND

Compatible with:

  • USB Mini-A plug (pre-OTG host)
  • USB Mini-B plug (OTG host, OTG client, pre-OTG client)

USB Mini-A receptacle (abandoned)

USB Mini-A receptacle

It was intended for host-only capable devices. It seems that it never reached mass production (fake photo).

Designated color: white

Pinout:

  1. Vcc
  2. D-
  3. D+
  4. ID (optional)
  5. GND

Compatible with:

  • USB Mini-A plug (pre-OTG host)

USB Mini-B receptacle

USB Mini-B receptacle

Connector for client devices and host devices that support OTG. If the ID pin is grounded by the cable, device should switch to the host mode and turn Vcc on. If the client voltage is present, device should switch to the client mode. It's one of the most common connectors. After introduction of OTG it is sometimes called as USB Mini-C.

Designated color: black

Pinout (client):

  1. Vcc
  2. D-
  3. D+
  4. unused
  5. GND

Pinout (OTG host):

  1. Vcc
  2. D-
  3. D+
  4. ID (host cable identification)
  5. GND

Pinout for (OTG host+client):

  1. Vcc/client voltage detection
  2. D-
  3. D+
  4. ID (host cable identification)
  5. GND

Compatible with:

  • USB Mini-B plug (OTG host (optional), OTG client (optional), pre-OTG client)

Note: Optional support means: It is mechanically possible, but the implementation is not mandatory for particular device.