SN74HCT04A: SN74HCT04A

Aradhyasambhu Satpathy

Part Number: SN74HCT04A

Hi all,

As per the datasheet of SN74HCT04A, the Max. Value of VIL = 0.8 V which means the output should not go high till the input voltage goes below 0.8 V.

But when I am simulating using the spice model in TINA - TI, my output is going from high to low when my input is going above 2.5 V and the output is going from low to high when the input is going below 2.5 V.

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 272970 points

V_IL is the maximum voltage at which the input reads a low level. V_IH is the minimum voltage at which the input reads a high level. All voltages between V_IL and V_IH are invalid and do not guarantee any specific logic level.

The actual switching threshold is somewhere between V_IL and V_IH. In the simulation, it is at 2.5 V, but real devices are likely to behave differently.

0 Chad Crosby over 4 years ago in reply to Clemens Ladisch

TI__Expert 6680 points

Hi,

Clemens is correct, we simply have our models switch at around 1/2 VCC.

Thanks!

Chad Crosby

0 Aradhyasambhu Satpathy over 4 years ago in reply to Chad Crosby

Intellectual 540 points

But I need to chose my component based on VIL. Is there any way I can tweak my .cir file to put 0.8 V instead of 2.5 V.

0 Chad Crosby over 4 years ago in reply to Aradhyasambhu Satpathy

TI__Expert 6680 points

Hi,

The VIL max spec simply means that 0.8V is the guaranteed highest voltage that our device will recognize as a logic LOW. Due to process variations and other operating conditions, some devices may recognize 1V or even 1.2V as a logic LOW. However, we guarantee that for every device, regardless of operating conditions or manufacturing process variations, our device will recognize 0.8V and lower as LOW.

Our devices do not switch at the VIL and VIH specs, they switch somewhere in between.

Thanks!

Chad Crosby

Logic

Logic forum

SN74HCT04A: SN74HCT04A