SN74LVC2G07: Schematic verification

Hi Irfan,

Based on this schematic, I'm concerned because I do not see any pull-up resistors on the output. SN74LVC2G07 is an open-drain output device, so it needs to have a pull-up resistor to 1.8V if you want to high-level output to be 1.8V.  [FAQ] What's the difference between logic output types (push-pull, open-drain, 3-state)? 

Irfan Shaikh said:

So the buffer input is 1.8V from PS FPGA and output will be 1.8 right? 

Output depends on the pull-up voltage on the output of the device. If you want 1.8V at output, you either need a push-pull device, or you need a pull-up resistor to a 1.8V rail. If you would prefer a push-pull device, take a look at SN74AUP3G34.

Irfan Shaikh said:

So can the PWM directly connected to the PWM which is internally PU and connected to 5V input

You can connect the output of the SN74LVC2G07 to 5V via a pull-up resistor if you want a 5V output from this device, but you need to use a resistor large enough to ensure that the current does not exceed the device's IOK of +/- 50mA. Take a look at https://e2e.ti.com/support/logic-group/logic/f/logic-forum/936385/faq-can-you-pull-up-an-open-drain-output-to-a-higher-voltage-than-the-device-s-supply-vcc-voltage/3458615#3458615 for more information.

Regards,

Nikki

Hi Nikki,

Based on this schematic, I'm concerned because I do not see any pull-up resistors on the output
------> Sorry for that , i have given the PU option of 4.7K pulled to the same Voltage what is given for the Fan i.e. 5V.

So the input 1.8V PWM signal is not related to the output, instead the PU resistor defines its voltage?
Is this correct what i said?

You can connect the output of the SN74LVC2G07 to 5V via a pull-up resistor if you want a 5V output from this device, but you need to use a resistor large enough to ensure that the current does not exceed the device's IOK of +/- 50mA.
-------> Could you suggest a resistor value?

Also if i am not using one input the i should connect it to the GND right?

Regards,
Irfan