Hi there I need an alternative component to Ricoh RN5RF50AA as i seem only to be able to purchase a minimum of 3000 of these. Not bothered about the pinouts matching as i’ll make up a small pcb for it and hardwire that to the location of the bad component on the main pcb. However if anyone knows of a direct match in SOT23-5 format that would be perfect? The component is marked “50” “504” or “50B” (shown at IC13 on the photo) I believe, and that led me to the Ricoh IC which is used as a PNP power transistor base driver to derive 5-6v from a 9v supply. pins 1 & 5 Gnd, pin 4 feds transitor base, pin 3 on collector of transistor, pin 2 emitter. Many thanks all
As possible alternates, you could try Nisshinbo RN5RF50AA-TR-Fe or Nisshinbo RN5RF50BA-TR-FE, but from what I see stock is limited.
Good luck!
Many thanks but that’s exactly what I’m asking for an alternative to rn5rf as these can only be ordered 3000 at a time on a real 
I’m sorry, I found no small quantity alternate for the RN5RF50AA.
That’s not a bad shout on initial glance.I’ll check it out. To all I assume I could use any 5v regulator to drive the PNP base?
Not really. The reference device and the 1662-2678-1-ND suggested would be properly classified as linear regulator controllers, which are devices designed to drive an external transistor to perform a linear voltage regulation function. The suggested alternative device got improperly classified among the “linear regulators” which are devices that integrate the pass transistor, rather than being designed to drive an external one.
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I’ve now received the alternative component thanks for the help BUT this component enable requires a HIGH as opposed to a LOW on the enable pin, how would I achieve that? Datasheet it says link to the Vin to the CE pin but will this work please?
Also i was rethinking the circuit application, so the original RN5RF voltage regulated via a PNP transistor, with various other features, over current etc. Is there any reason, if only to get the circuit working, i couldnt simply use 5voltage voltage regulator such as L7805ACV to derrive the 5V VCC from the Vdd of 9volts please?
If this helps here is the enable min typ max voltage values. Seems to me these are back to front in the datasheet, surely a Low is less than 0.3v and a high in minimum 2.4v but it shows this…
A pull-up resistor and N-channel FET with sufficiently low threshold should do. One could also buy an inverter should one care to go that route.
That’s how one ensures the device will operate in the case where the control signal is unused. Very typical practice.
Specs for the original don’t seem to exotic, so there’s a fair chance that could work as a duct-tape fix.