Hex buffer SN7407 pull up resistor value

[manishanand14]

Hello Everyone!

I am feeding 5V pulses and want to convert it to 15 V pulses.Please suggest me the pull up resistor value for 15 V output.
Also please tell me the current rating of the open collector transistor. Is it given in the datasheet?

 

[betwixt]

Typically the maximum current is about 40 mA, the TI data sheet lists it under parameter 'IOL' which is misleading as it does not 'output' any current in high or low logic states. The logic low output voltage does rise as more current is sunk at the output pin though.

The value of the pull-up resistor must be high enough that the 40mA limit is not exceeded, (15/0.04 = >375 Ohms in your case) but it really depends on how much current the following circuits need as the resistor will also be feeding current to them. The maximum resistance can be any practical value, it depends on leakage currents and the load but could easily be > 100K Ohms.

Brian.