cd74hct4067-Q1 usage

Srikanth R

Other Parts Discussed in Thread: CD74HCT4067-Q1

Hi,

I want to know two things about this IC:

1. is it ok to connect VCC to 5V and S0-S3 to signals at 3.3V?

2. Is it ok to drive a solenoid of 62ohm & 5V rating through this device where i/p is connected to 5V and o/p to solenoid (as On resistance is 70 ohm and max current rating is 50mA)?

Regards

Srikanth

over 9 years ago

0 ShreyasRao over 8 years ago

TI__Guru 57780 points

Hi Srikanth,

I will review and reply on this .

0 ShreyasRao over 8 years ago in reply to ShreyasRao

TI__Guru 57780 points

Hi Srikanth,
The HCT works with 3.3V signals on Select lines.
The abs max output source or sink current is 25mA beyond which the functioning is not guaranteed and the 50mA is the continuous current through Vcc /Gnd . I would recommend to stay well below this to have good reliability.

0 ShreyasRao over 8 years ago

TI__Guru 57780 points

Srikanth ,
yes, you can remove the level shifter.
It is mentioned in the datasheet in the recommended operating conditions section .

0 Srikanth R over 8 years ago in reply to ShreyasRao

Expert 2650 points

Hi,

Minimum input high voltage requirement at 4.5V Vcc is given as 3.15V. At 5V of Vcc it may be more!

Keeping in account the tolerance level of regulators, in some cases I may not get 3.3V. So, it may be safe to go ahead with the levelshifter. What do you suggest?

Thanks
Srikanth

0 ShreyasRao over 8 years ago in reply to Srikanth R

TI__Guru 57780 points

I am not sure where are you looking at but here is the datasheet for CD74HCT4067-Q1 .

In the recommended conditions , you can see Vih and Vil .Although , assuming the variation from regulators shouldn't be more than 0.1V , if you are concerned ,there is no harm in having a buffer accepting TTL inputs.

0 Srikanth R over 8 years ago in reply to ShreyasRao

Expert 2650 points

Hi

I have mistakenly looked at HC type instead of HCT type. For HCT min. high level input is 2V at 4.5V Vcc. So, it should work without level shiter

Thanks

0 Srikanth R over 8 years ago in reply to Srikanth R

Expert 2650 points

Hi, is it ok to connect inputs without connecting Vcc to this IC?

Thanks

0 ShreyasRao over 8 years ago in reply to Srikanth R

TI__Guru 57780 points

Hi Srikanth ,

This is not recommended , since there are ESD diodes present internal to device which can turn on and potentially damage the device.

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cd74hct4067-Q1 usage