The explanation of capacitance loading

[ee_montoya]

capacitance loading

A very elementary question. What does it mean when we say, this can drive a capacitance of 20 pF. can someone explain the physical meaning.

 

[IanP]

Re: capacitance loading

It means that this "driver" can charge and discharge a capacitance in requested period of time, which is usually very, very short ..
A mosfet transistor is a good example of capacitive load. If you want the rising and falling edges of an impulse to be very sharp you have to ensure that a driver connected to the mosfet's gate can within nanoseconds charge or dischrge the capacitive load of the gate. Longer switching time - more energy wasted as heat..

 

[EEHardware]

capacitance loading

i think what IanP said is good explain,capacitance loading is current driver

 

[ee_montoya]

Re: capacitance loading

thanks ! now feels definitely better. i had come across this, a sensor chip output is connected to an A/D converter. the sensor chip spec says it can max drive a load capacitance of 20 pf and the a/d converter says its input capacitance is 7 pf. and the pcb traces will add some capacitances. so there isnt any problem in here as far as the sensor driving the a/d converter inputs ?

 

[IanP]

Re: capacitance loading

You should be within safety margin with these given values.
Just, where possible, try to keep traces short and direct.

 

[pyth2004]

Re: capacitance loading

larger capacitance loading means longer time to charge up the cap., thus slower the frequency response. Similarly, smaller cap. loading requires lesser time to charge up result in faster frequency response.

Hope this can help you