SN74HC595: Output drive current in 3.3V supply

Shuang Feng76

Intellectual 2990 points

Part Number: SN74HC595
Other Parts Discussed in Thread: SN74HCS595, SN74AHC595, SN74LV595A

Hi team,

here we want to check the output drive current in 3.3V supply.

there is only have data for 5V supply as below.

i also see it will decrease in low voltage.

do we have 3.3V Vcc data?

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 243110 points

You can use linear interpolation; see [FAQ] What method is best used for estimating specification values between those given in the datasheet? So you would have about 3.1 mA drive at 3.3 V.

But HC is a very old logic family. More modern devices have 3.3 V specifications, e.g. SN74AHC595 (4 mA) or SN74LV595A (8 mA) . The SN74HCS595 is cheaper with the same specifications as the HC.

0 Shuang Feng76 over 1 year ago in reply to Clemens Ladisch

TI__Intellectual 2990 points

thank you very much.

so that means the logic device could have same drive ability when the power drop from 5V to 3.3V. Due to it is linearity degrade. am i right?

0 Clemens Ladisch over 1 year ago in reply to Shuang Feng76

Guru 243110 points

The FAQ says that the degradation can be assumed to be linear between the specified 2 V and 4.5 V values.

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SN74HC595: Output drive current in 3.3V supply