cathode for HP91

[Katie Wasserman]

(07-30-2015 06:29 AM)isanchez Wrote:  - 1820-1629, integrated circuit , cathode driver

I have replaced it from a working 97 and works fine.

Could you please tell me if there exists an equivalent reference available to buy?

Unfortunately there is not an equivalent chip. The cathode driver is also the keyboard scanner and the low battery detection chip, it's relatively complicated and would be difficult to replace with anything other than a programmed microcontroller. (The project that I described here implicitly describes how the scanning works using the RCD and STR control lines.)