LM3914.....How fast is it?

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Alec_t

Joined Sep 17, 2013
14,407
I can find nothing in the Nat Semi / TI datasheet about the speed of response of the IC to changes in the input signal at pin 5. I have a possible application in mind where the input is an audio signal and the ten outputs drive circuitry other than LEDs, so flicker and eye response are not an issue. Anyone have any info on timing constraints for this handy IC?
 

Irving

Joined Jan 30, 2016
4,047
Just done a quick test with a LM3914-1 I happened to have lying around.

5v supply, 1k Iled current set gives about 3.5v swing on 220R load resistors

Max useful freq input 100kHz, but LED 'on' times may be compromised.
At 10kHz:
Square wave input 0 - 4.75v. Dot Mode.
Rising edge to LED0 OFF, 500nS, rise time, 1.5v->5v 100nS
Rising edge to LED10 ON, 4.6uS, fall time, 5v->1.5v 200nS

Falling edge to LED0 ON, 2.3uS. fall time, 5v -> 1.5v 200nS
Falling edge to LED10 OFF, 500nS, rise time 1.5v -> 5v, 100nS
 
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