What is the maximum output current of a logic gate at 5V VCC?

[TheRedDevil18]

Hi, I have this logic gate
http://www.ti.com/lit/ds/symlink/sn54hc32.pdf

I am using 5V as my VCC. In the datasheet it says that the output current at 6V is 5.2mA. My question is, Is that the max current that it can output ?

 

[Jony130]

My question is, Is that the max current that it can output ?

For sure not.
http://www.nxp.com/documents/user_manual/HCT_USER_GUIDE.pdf (page 34)
You can drawn more current but Voh voltage will drop bellow Vih (High-level input voltage ), so the next gate will not be able to properly recognize the logic state at his input.

 

[TheRedDevil18]

For sure not.
http://www.nxp.com/documents/user_manual/HCT_USER_GUIDE.pdf (page 34)
You can drawn more current but Voh voltage will drop bellow Vih (High-level input voltage ), so the next gate will not be able to properly recognize the logic state at his input.

Ok, is there any way to know by how much it might drop ?, I am feeding it to the base of a transistor

 

[Jony130]

How much base current do you need? Also if you drive a BJT base only then you do not have to worry about VIh any more because the BJT is not a logic circuit so you do not have to meet the logic level regiments. Also we can find in datasheet the info that Io_max = 20mA
https://en.wikipedia.org/wiki/Logic_level#Logic_voltage_levels

 

[TheRedDevil18]

How much base current do you need? Also if you drive a BJT base only then you do not have to worry about VIh any more because the BJT is not a logic circuit so you do not have to meet the logic level regiments. Also we can find in datasheet the info that Io_max = 20mA
https://en.wikipedia.org/wiki/Logic_level#Logic_voltage_levels

Assuming the output voltage from the ic is 5V which I used to calculate my base resistance. The current would be about 5.5mA

 

[Jony130]

No worries here the gate will survive this.
As we can see from this characteristic

The voltage drop across the gate output will not be larger than 0.8V and typically it will be around 0.3V.

 

[TheRedDevil18]

No worries here the gate will survive this.
As we can see from this characteristic
View attachment 98723

The voltage drop across the gate output will not be larger than 0.8V and typically it will be around 0.3V.

Thanks, So I can assume the output voltage from the gate and hence the voltage to the base of my transistor will be about 4.7V ?

Also, from the same datasheet, how much current does the ic draw when one of the pins is held high ?, I want to calculate a pull up resistor to ensure that the pin gets close to 5V as possible. I read around and they about 5k to 10k should be fine

 

[Jony130]

So I can assume the output voltage from the gate and hence the voltage to the base of my transistor will be about 4.7V ?

Yes.

Also, from the same datasheet, how much current does the ic draw when one of the pins is held high ?

The current consumption will depend on the load resistance. Because CMOS circuit in static do not burned any power. Only the load will consume power from power supply.

Also, from the same datasheet, how much current does the ic draw when one of the pins is held high ?, I want to calculate a pull up resistor to ensure that the pin gets close to 5V as possible. I read around and they about 5k to 10k should be fine

Do you really want to put a pull-up resistor at the gate output? Why ?

 

[TheRedDevil18]

Yes.

The current consumption will depend on the load resistance. Because CMOS circuit in static do not burned any power. Only the load will consume power from power supply.

Do you really want to put a pull-up resistor at the gate output? Why ?

I wanted to create a NOT gate using a transistor. But I don't need it now because I have an ic for it

 

[CWatters]

Can I suggest you post a sketch of this bit of your finished circuit?