SN74HC573A-Q1: If some unused channel input and output pins are floating, will it influence other used channels?

Johnny Guo

Expert 4910 points

Part Number: SN74HC573A-Q1

Hi, team,

In SN74HC573-Q1 datasheet, unused input pin is recommend to tied to VCC or GND.

But if some unused channel input and output pins are floating, will it influence other used channels?

Thanks.

Johnny

over 6 years ago

0 Clemens Ladisch over 6 years ago

Guru 316510 points

The primary effect of a floating input is a very high cross current that flows through that pin's input transistors. However, this current goes through V_CC and GND, so the voltage drop induced there can affect other gates.

Furthermore, if the floating voltage is near the threshold, it can induce oscillations, and the current spikes from all those switching transistors certainly will affect the entire device.

0 Dylan Hubbard over 6 years ago in reply to Clemens Ladisch

TI__Mastermind 45725 points

Hi Johnny,

Don't forget to check out our FAQs as you might find your answer there and get a quicker response. Here is an FAQ that relates to your question, let me know if you have any further questions.

https://e2e.ti.com/support/logic/f/151/t/737694?tisearch=e2e-sitesearch&keymatch=faq%3Atrue

0 Johnny Guo over 6 years ago in reply to Clemens Ladisch

TI__Expert 4910 points

Thanks Clemens.

0 Johnny Guo over 6 years ago in reply to Dylan Hubbard

TI__Expert 4910 points

Dylan,

Thanks for reminding.

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SN74HC573A-Q1: If some unused channel input and output pins are floating, will it influence other used channels?