Mystery voltage regulator

How do you know it's a regulator?

Tom

By following the PCB traces, I can see that the power input from the

9.5V AC wall wart goes through a full-bridge rectifier (labeled 17 in the picture) and then from the "+" pin on the rectifier to one of the pins on the regulator. When the regulator is in place, the rectifier gets quite hot quite quickly. After removing the regulator from the board, the rectifier no longer gets hot.

The web site on which I found the picture:

describes it as "Voltage Regulator with 5V".

I just found this forum discussion:

I don't understand Polish, but a Google translation at least strengthens the theory that it is a voltage regulator. They refer to it as 4307dv33, which seems to give a few more sensible and very promising hits on Google...

Can you see a voltage rating on a capacitor on the + line?

Tom

There are two large capacitors, both marked:

470 10A 4F8

Would that mean 10V? Capacitors are not normally rated in amps, at least not on the markings.

I can't quite see where the caps are connected, though, since they sit completely in contact with the PCB, hiding the traces.

From a new Google search, I found a Russian forum suggesting the regulator is a TLE 4307 DV33. A further search lead to this:

I took a chance that it is indeed an Infineon TLE 4307 DV33, so I connected 3.3V from a lab supply to where the regulator's output pin would go. It worked! I got a dial tone and correct communication between handset and base. The handset did not charge, though.

Some of the traces are difficult to follow, but it seems they take battery charge power directly off the charge-pump capacitor. That leaves two possibilities. One is to find out which voltage is normally on the charge pump, and then use a separate regulator to drive that. The other, and simplest, option is to find a replacement regulator. My normal suppliers don't list it. Any ideas where to find one?

You are doing some good work. The 3.3 may not be the only output for that regulator. If it were me at this point, I would put in the TLE 4307 DV33.

Tom

According to the data sheet, it is the only *intended* output. It seems the designers are "abusing" the charge pump to provide power to the battery charger.

I will. If I can find one. Mouser lists it, but have 16 weeks delivery and 1200 minimum order. Farnell don't list it. Digikey list it, but have 2500 minimum order.

Any ideas?

See if you can get an "engineering" prototype sample.

--
It\'s an obsolete part, so some of the surplus vultures may have some.
$$$, tho...

Try:

http://www.sierraic.com/pnresults.asp?part=TLE4307&btnsearch=Search

JF