1858-0044 ?

[jklsadf]

Hi, for V_CE(sat), the requirement for 1858-0044 is listed as V_CE(sat)=0.3V max for I_C=400mA and I_B=8mA from 0 to 50 °C, and V_CE(sat)=0.45V max for I_C=600mA and I_B=12mA (no temperature listed, so only at 25 °C ambient). It's unclear if these are supposed to be pulsed ratings. The h_FE is specified as min 70 and max 400 for I_C=500mA and V_CE=1V. V_BE is specified as 1.2V max for I_C=500mA and V_CE=1V. Power dissipation is listed as 500mW absolute max for each transistor, and I_C as 600mA absolute max (but I'm assuming HP didn't run any of these anywhere near the absolute max, at least not continuously).

Apparently GE and Motorola used to be second sources for 1858-0044, but I have no idea what part numbers. The specs for a 2N2222 aren't as good, but it seems like people have substituted them successfully for some applications. It might be possible to substitute a logic-level nFET as well.

As far as the source, I can't share the source for cross referencing 1858-0044 to CA3138G, since it's not publicly available info. (I probably shouldn't actually be sharing this info, but it's for a long-obsolete part (albeit with specs that are difficult to find modern substitutes for), and hopefully it might be useful to people trying to repair old equipment.)