Need a SSR to connect to RS-232 and draw under 10mA

[ElectroNewby]

Good day ppl,

I'm trying to find a SSR to plug into a RS-232 that provides 12Vdc.
From what I could find on RS-232 drivers, the cheap ones with ICs have a max of 10mA.
I was looking at the SSL1D101JD, but I'd really like if someone in the know could confirm that at 12Vdc it will only draw 4mA:

Long story short, it's to use with a Toshiba T1000 UPS and monitor a low-battery alarm.
They say not to use the RS-232 for remote contacts (because they sell a 3-400$ module to do that) but connecting a 12V 10mA relay works perfectly with pin 9 and 8 here:

Pin 9 (12Vdc) → A1 → A2 → Pin 8 (low batt). When the low batt occurs, pin 8 becomes linked to pin 5 (with a certain resistance though, I don't know why and if it matters... 128 Ohm between pin 8 et 5).
Anyway, the 12V 10mA relay works, but I don't want to burn anything in the long run so I'm really trying to find a solution under 10mA.

Thank you so much for your help !

 

[tumbleweed]

It has an input resistance of 1250 ohms, so with 12V, that'll pull pretty close to 10mA.
You could add an external resistor, just make sure you end up with > 3V across the control input and at least 4mA.

 

[rjenkinsgb]

It should be fine.

I'd read the Not "Dry contact purposes" etc. as a warning that the outputs cannot be interconnected with any other powered equipment.

(A "dry contact" is such as a set of relay contacts that have no electrical connections, so can be used to switch external power & signas).

Running the SSR LED between it's own 12V and signal pin is fine, that's using it as intended.

 

[tumbleweed]

Running the SSR LED between it's own 12V and signal pin is fine, that's using it as intended.

Isn't that doing exactly what it tells you not to do (use external power)?

The RS232 connector has a 12VDC output... why wouldn't you use that to power the SSR LED along with the Low Battery Output?

 

[plouf]

cpc1017 i use a lot , it is activated with 1ma in its led so a 10kohm resistor in series will fully activate it

dependict what and how you want to activate a simple PC817 could also work but almost certain will need to drive a transistor in its output

 

[crutschow]

The SSR input impedance is 1250Ω and the input SSR diode voltage is likely about 1.2V for the usual IR control input LED, so the input current at 12V would be about (12V - 1.2V) / 1.25k = 8.64mA.

If you wanted to lower than some (to say 5mA) you could add a 909Ω resistor in series with the input.

 

[rjenkinsgb]

The RS232 connector has a 12VDC output...

= The units own power??

 

[tumbleweed]

= The units own power??

Yes, that way you're using the RS232 unit's 12V and common to power the input LED of the SSR.
"Pin 9 (12Vdc) → A1 → A2 → Pin 8 (low batt). When the low batt occurs, pin 8 becomes linked to pin 5 (Common)"

 

[rjenkinsgb]

Isn't that doing exactly what it tells you not to do (use external power)?

Sorry, but that just confused things completely; there is no other 12V "power" in the equation, between the UPS and the SSR, so I don't understand your comment there.

 

[tumbleweed]

I think perhaps I misunderstood what you meant when you said "Running the SSR LED between it's own 12V and signal pin is fine", taking the "it's own 12V" to mean using something other than the 12V available on pin 9 of the RS232 interface connector.

My bad.

 

[Tony Stewart]

Why RS-232? and not just a logic level, LED and piezo alarm.