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SN74HC14: Continuous current Vs Source/Sink current specification in practical Application for74HC14

KPA
Prodigy 220 points

Part Number: SN74HC14

Hi,

I am planning to drive LED using 74HC14 which will sink current around 10mA.

The datasheet of 74HC14 does have "continuous current" IO specified for +/-25mA while IOH & IOL is tested for +/-5.2mA in recommended specification.

So what to consider as output driving current capability of the pin, IO or IOH/IOL ?

Is it ok to load the 74HC14 pins for 10mA sinking current for long time of operation ? OR it will degrade the IC with time ?

Regards,

  • 0
    Guru 326780 points

    As long as you stay inside the absolute maximum ratings, the device will not be damaged. So you are allowed to try to sink 10 mA into an output.

    However, the recommended operating conditions limit where correct operation is guaranteed. In particular, when you sink more than 5.2 mA, the VOL specification will be exceeded.

    The specified output impedance is typically 0.15 V / 5.2 mA ≈ 29 Ω. You could simply adjust the current-limiting resistor for the LED by that amount. (The worst-case output impedance is 63 Ω; the resulting reduction in LED current probably does not really matter.)