SN74ALS240/244/245: Vcc=0V

toshi-e2e

Hi all,

When Vcc=0V and output pins are pulled up to 5V with 330-ohm register, what does happen to IC?
I understand that SN74ALS240/244/245 do not have the function of power-off output disable.

How does an electric current from an output pin float down a circuit inside of the IC?

Thanks in advance.
Regards,
Toshi

over 8 years ago

0 Clemens Ladisch over 8 years ago

Guru 256100 points

Figure 12 of the Advanced Schottky application report shows an ALS output:

A current could flow through D3 and R3.

0 ShreyasRao over 8 years ago in reply to Clemens Ladisch

TI__Guru 56750 points

Thank you , Clemens for your valuable inputs on this .
Not advisable to have higher voltage than Vcc on the outputs . This device family doesn't have Ioff protection circuitry which would allow higher voltage on the inputs and outputs when Vcc =0.

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SN74ALS240/244/245: Vcc=0V