Slew Rate , Generators Slew Rate and Op Amps Slew Rate DC component

[danny davis]

What are the bad things about a generators slew rate?

What kind of problems can a generators slew rate cause?

When you overload or Draw to much current from a Generator, its causes a slew rate problem , how can you fix this type of problems when there is a current surge or overload on the output of a generator, causing it's slew rate issue?

Op amps don't have a DC offset on the input and output?

When there is a DC offset or DC component on the input, it causes to mess up the OP amps Slew Rate?

 

[sreekumar27]

I think by generators you mean Function Generator?
Slew is not always bad. Practically there can not be any system without slew. low Slew gives a advantage of very less over/under shoots. But slew is very important when working with high speed digital designs like FPGAs and processors. If the slew is less than recommended at input of a digital circuit, the circuit can oscillate or shoot through when signal is traversing through no-logic region (in-between ViL and ViH)
To improve slews you should use a buffer. Preferably a buffer with Schmidt inbuilt. The 74AC series buffers gives you rtr&tf of 3-5ns. 74HC gives ~5-10ns. You choose a correct buffer for require load and slew. When you drive multiple circuits it always good to use different and dedicated buffers to each. If too many destinations are present try tree-replication to increase fan-out.
If you need to support surges driving a circuit use capacitive coupling. Make sure the capacitor is high quality, High Q, low ESR, High frequency type.
I couldn't understand you second last question. However DC offset don't affect slew of a op-amp.

 

[danny davis]

Generator I mean an AC 120 VAC generator that uses a Motor, The generators Motor has a Slew Rate

When you "overload" or a "Current in rush" on the output of the Generators motor, it will slow down the motor and it ramps up / slew rate changes causing a ramping down and up

Why does have a High Slew rate cause over or under shoots?

How can a slew rate cause Oscillations?

 

[sreekumar27]

Sorry I don't know much about motors

High Slew rate cause over or under shoots - The PCB trace or wire or even ICs pin is combination of L, C and R. The values are so small that when signal tr and tf is small they do not affect the signal. Hence signal slews smoothly. When the slew rate is high the high frequency component in signal is dominating and these LCR becomes accountable. The LCR has it own resonance and damping levels. With high slew rates these components resonate and dampen off. The resonance gives raise to overshoot and undershoot

How can a slew rate cause Oscillations - Yes low slew rates can create problems in clocking circuits. You can see many devices will have specifications has max rise time fall time. If slew is not met for this. The device input section will be go to unknown state signal is traveling in region between ViL VoH. internal transistors starts switching ON and OFF or switch on together because the state is undefined. Hence the next circuit will take it as clock edge and create multiple triggers