Supply current of linear LED driver IC when LEDs off?

[eem2am]

What is the supply current of the following linear LED driver IC when REXT = 1K and all LEDs are OFF.?

(REXT is the LED current setting resistor)

LED DRIVER = STP16C596 DATASHEET:-
http://www.datasheetcatalog.org/datasheet2/a/0sth3q6zylj9i17uxwhkdjd3ijwy.pdf

..page 4 of the datasheet only gives supply current for when REXT = 470R and 250R.

 

[alexan_e]

Yes the datasheet gives only rating for 470R=5.5mA and 250R=10.1 but it is a linear relation

470*5.5mA is 2.585v
250*10.5mA is 2.625v

so if you calculate with a mean value of 2.6v/1k=2.6mA

Alex

 

[eem2am]

Thankyou,

I see that the linear relation does look the most likely thing.......

-but then however, if it really was linear over all values of REXT, then i thought they would have put a graph showing it thus.

-So I am not convinced that its linear over all values of REXT.

 

[FvM]

There are two possible answers, depending on your intention:

- If you want to know the expectable current, Alex' calculation is pretty reasonable. You can make it even more exact by considering the third REXT = open point, and get 2.2 mA and an nearly perfect linear relation.
- If you want to read a guaranteed maximum current from the datasheet, e.g. for a power supply dimensioning, all calculations and estimations are void. The only validated assumption is, that the current will be below the specified maximum current for REXT = 470R.