Component Identification

[Hendrik]

Hello,

I am trying to repair an IR remote control. The device is about 17 years old.
The component in question has a SOT-89-3 package with "AA P76" markings.

Pin 1 is input of a voltage divider (12k & 1k)
Pin 2 is Vout feeding an Atmel microcontroller capable of up to 5.5V input
Pin 3 is Vin

Vin is fed by 4xAAA batteries in series at about 6V.

All my research led me to these voltage detectors: https://product.torexsemi.com/en/system/files/series/xc61f.pdf
But the pinout does not match and I can't find any more suitable ic from these markings.

When manually feeding 4.2V at Pin2 and 6V at Vin the remote control is functional.

Anyone knows what type of component this is? I have never seen or used a Voltage Detectors (if thats what it is) but from the position it would make sense I guess.


Kind regards,
Hendrik

[jwet]

Its a high beta PNP transistor being used to manage power.  The uP can run on any voltage from 3-6V- no regulator is required, this PNP just lets battery current flow when a button is pressed or when the unit is active.  The diode D15 is used to allow the uP to keep power on after a button is touched, etc.

The designator T?  is a designator for a transistor, not an IC.  Its a PNP transistor that is used as a power switch.  The transistor is a bit grunty because the LED's draw some real currents.  Pin 1 is the base, pin 2 is the collector and pin 3 is the emitter.  Normally the base is pulled up with the 12k.   When any button is pressed,- T2 (an NPN) is turned on and pulls on the 1K, R29 to sink current turning the PNP on.  Some thing with a beta of 50-100 and an Ic max of 500 mA peak, you can measure.  Package is SOT-89-3.  Shouldn't be hard, look at Digikey, Mouser, Farnell, etc.

[amyk]

BCX51?

[Hendrik]

Thank you guys for the help. I wasn't so aware of the T designator for bipolar transistors, more used to Q.
I still have some PNP power transistors from an e-bike display repair: https://www.lcsc.com/datasheet/C41375139.pdf that seem to work good so far.

[jwet]

The T? thing for transistors is sort of an Asian consumer electronics thing- it was also used in old european stuff. The US's  Q? designator is sort of a strange letter for this- don't know the story.