Datasheet of XRU8871

[triss64738]

Hi,

During the holidays, my dad asked me to fix an old device of his. There doesn't seem to be any visible damage (eg. leaking caps or corrosion on the PCB), so I wanted to check if all the ICs on it are still functioning correctly. However, for many of these chips I can't find any documentation whatsoever. (The device is from '93, one part bears a datecode marking of the 49th week of 1992). One of these unknown chips is an XRU8871 (photo attached below), which, according to this page, was manufactured by ST. (I also already tried contacting ROHM, to no avail, and I've also just posted a question on the TI E2E forum as TI and NS are also listed as manfuacturers.) Does anyone happen to know anything about this chip?

Thanks

Photo of the chip:

(FYI, the big chip on the bottom is an HMCS400-series 4-bit microcontroller.)

[Tesla DeLorean · Accepted solution]

Some kind of answer phone/fax ?

DTMF decoder? BU8874 Similar

https://www.mouser.com/datasheet/2/348/rohm_semiconductor_rohms30191-1-1742744.pdf

https://www.sourcengine.com/download-datasheet/BU8871-DX-1446373736

Can you identify any of the power and signal pins, might pin things down a little.

Perhaps it's something like this?

https://components101.com/ics/XPT8871-audio-amplifier-ic-pinout-datasheet-circuit

[triss64738]

Yeah it's a phone answering device (Panasonic Easa-Phone, KX-TI450M is the part number on the PCB). Pins 2 and 4 are connected to GND, pin 8 seems to be VCC. That rules out the XPT8871. Pins 5, 6 and 7 are connected to the MCU. Pin 3 is connected to a xtal, and pin 1 goes way off. So I think the BU8874 sounds right, thanks!