How does one find what base current to use in simulating a phototransistor?

Question

I wish to use LTspice to simulating a phototransistor (LPT80), so I downloaded the model but I have not found information on the base current to use?

And how do I relate the base current to daylight?

Is there a better way to know than trial and error? eg -1mA does turn it on and 0A does turn it off.

That diagram looks wrong. Shouldn't the current be going into the Base? — Bruce Abbott, Nov 12, 2020 at 3:33
Yes, it is as I'm using negative current. It is just a test circuit. :) — Geoff, Nov 12, 2020 at 6:15

analogsystemsrf · Accepted Answer · 2020-11-12 03:26:13Z

1

Photodiodes are typically spec'd at 0.5 amp per watt of photon flux.

So work from that concept.

answered Nov 12, 2020 at 3:26

analogsystemsrf

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\$\begingroup\$ Interesting, so is that "0.5A" collector emitter current "per watt of photon flux"? Do you have any reference? \$\endgroup\$
– Geoff
Nov 12, 2020 at 6:01
\$\begingroup\$ Photodiodes don't have collector current. (Reference any photodiode datasheet). Since a phototransistor's base region is the photodiode. take that as 0.5A/watt of base current. \$\endgroup\$
– user_1818839
Nov 12, 2020 at 14:39

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