SN74LV4040A: How to interpret "Support Mixed-Mode Voltage Operation on All Ports"

Fan Yi

Part Number: SN74LV4040A

Hi,

I'm trying to interpret the feature statement in the datasheet claiming that "Support Mixed-Mode Voltage Operation on All Ports".

Does it mean the port could work with 5V signal stress even its power supply is 3.3V?

Thanks.

over 7 years ago

0 Fan Yi over 7 years ago

Intellectual 280 points

I tend to use this part with 5V signal on its CLK port meanwhile with 3.3V signal on its CLR and Qx ports.
If it is possible, which VCC level would you recommend, 5V or 3.3V?
Thanks.

0 Emrys Maier over 7 years ago in reply to Fan Yi

TI__Guru* 97396 points

Hi Fan,
If you want the device to output 3.3V, then the supply must be 3.3V. The inputs of this device can be 5V with a 3.3V supply.

0 Fan Yi over 7 years ago in reply to Emrys Maier

Intellectual 280 points

Thanks Emrys.
Following statements still confuse me
"Typical VOLP (Output Ground Bounce)<0.8 V at VCC = 3.3 V, TA = 25°C"
and
"Typical VOHV (Output VOH Undershoot)>2.3 V at VCC = 3.3 V, TA = 25°C"
Does it mean in worst case the VOL could be as bad as 0.7V and VOH as bad as 2.4V?
It seems not to be a feature, but a flaw.

0 Emrys Maier over 7 years ago in reply to Fan Yi

TI__Guru* 97396 points

Hi Fan,

Perhaps the statement is confusing because you are not familiar with the term "Ground Bounce."

There is a great applications report on the topic of multiple output switching located here:

Simultaneous-Switching Performance of TI Logic Devices

Logic

Logic forum

SN74LV4040A: How to interpret "Support Mixed-Mode Voltage Operation on All Ports"