Connect power + peripheral to tablet with one MicroUSB

I have a tiny TV tuner pluggable into Android devices to watch public TV; MicroUSB plug. I have a charger with MicroUSB plug. I have an old tablet that can either play TV from the tuner until battery runs out (~1 hour) or charge from the charger. Either-or.

I guess the device I need should be trivial, likely some kind of cable with two MicroUSB sockets marked 'data' and 'power', and one USB plug. But I don't even know what it would be called to look it up to buy.

I'm not asking for recommendation of a specific model/brand, just the name of such a gizmo.