SN74HC00: Input voltage

soichiro kikuchi

Prodigy 250 points

Part Number: SN74HC00
Other Parts Discussed in Thread: CD74HC03

Tool/software:

The input voltage is not specified in the Absolute Maximum Rating

Is it only Input clamp current prescribed?

I will consider it from the IBIS model. I have received responses that CD74HC03 model can be used from the following.

IBIS model - Logic forum - Logic - TI E2E support forums

Please tell us about this way of thinking.

1 month ago

0 Clemens Ladisch 1 month ago

Guru 317000 points

Yes, you must limit the input clamping current. For practical purposes, if you do not want a clamping current to flow, stay between GND − 0.5 V and V_CC + 0.5 V.

0 Nikki Dengel 1 month ago

TI__Intellectual 1520 points

Hi Soichiro,

Clemens is correct about the need to stay between GND − 0.5 V and V_CC + 0.5 V.

For your question about the negative voltage, it is simply a convention. Please refer to the below screenshot from Figure 7-8 in the SN74HC00 Datasheet as an illustration of the clamping diodes in the device.

Regards,

Nikki

0 soichiro kikuchi 1 month ago in reply to Clemens Ladisch

Prodigy 250 points

I limit the voltage between GND − 0.5 V and VCC + 0.5 V.

However, questions remain about IBIS model. What does this mean?

Does that mean that 24.13mA flows to the power clamp diode when voltage is -5V?

When the voltage is more than Vcc+0.5V, the current should flow, right?

Why is voltage negative?

+1 Clemens Ladisch 1 month ago in reply to soichiro kikuchi

Guru 317000 points

As far as I can see, the POWER Clamp and GND Clamp tables have been exchanged. Look into the GND Clamp table for what happens when the voltage goes above V_CC.

0 soichiro kikuchi 1 month ago in reply to Clemens Ladisch

Prodigy 250 points

As you said, it seems to be written in the GND clamp.

+1 Nikki Dengel 1 month ago in reply to soichiro kikuchi

TI__Intellectual 1520 points

Hi Soichiro,

We only model the negative side of the power clamp because it's negative relative to VCC. Although we model a very large range of voltages for both the power and ground clamps, that doesn't mean you should operate at those voltages. Stresses beyond those listed under Absolute Maximum Rating may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Condition. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

Regards,

Nikki