Hello all,
I am working on a simple pre amp design with LM4562 and I will appreciate your thoughts and advises on that.
Here are the questions:
1) There is a 47 ohm resistor R16 right at the end of the output stage to isolate it from the cable capacitance.
There is another 47 ohm resistor R15 to limit in-rush current into coupling capacitor C5 which also prevents parasitic capacitance from cabling.
Is there a problem with this figure or in another word should I omit one of them or they are working just fine?
2) The voltage gain I needed for this stage was 2 so I chose 1k ohm for feedback resistors R11 & R14 and the reason for choosing 1k was for noise considerations.
Since the output current of LM4562 is around +/-26mA, I thought there wouldn't be a current issue when generally there is no need for output voltage more than 2 volts to drive any amplifier.
Is it safe to stay with 1k resistors?
I am working on a simple pre amp design with LM4562 and I will appreciate your thoughts and advises on that.
Here are the questions:
1) There is a 47 ohm resistor R16 right at the end of the output stage to isolate it from the cable capacitance.
There is another 47 ohm resistor R15 to limit in-rush current into coupling capacitor C5 which also prevents parasitic capacitance from cabling.
Is there a problem with this figure or in another word should I omit one of them or they are working just fine?
2) The voltage gain I needed for this stage was 2 so I chose 1k ohm for feedback resistors R11 & R14 and the reason for choosing 1k was for noise considerations.
Since the output current of LM4562 is around +/-26mA, I thought there wouldn't be a current issue when generally there is no need for output voltage more than 2 volts to drive any amplifier.
Is it safe to stay with 1k resistors?
The LM4562 can drive 600 ohms, so this circuit will work ok.
You can remove R15.
You can remove R15.
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What in-rush current? The other side of C5 is normally high impedance. Taking 22k leak and 22k load, say 10k total load and 14V starting voltage, there is at-most 1.4mA of in-rush. Modern chips supply 10mA-50mA without complaint. Not a problem.
If you expect momentary shorts, modern chips usually won't blow-up if you try to suck more. (As opposed to the ancient '709, which said it withstood momentary shorts, but my slow-shorts usually killed one.)
Sending high level into a short "could" wear-down a chip, but that's probably years. And not much resistance needed to tame that.
If you have shorts on one output in a multi-channel live situations, the supply spikes can dirty-up other channels' signals. There are guides for such extreme abuse but nobody here does that.
Of course there are , I just cropped the part I had questions with