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drjohsmith
- Joined Dec 13, 2021
- 1,662
The requirment on power for a chip , is dependent upon the chip and usage.
It's a great part of circuit design, trying to optimise performance , whils minimising risk, and maximising profit.
Most all chips are dc powered, and most all will require some form of local filtering ,.
The filtering does two things, smother out any noise on the incoming supply so the chip sees quieter supplies, and on noisy chips, stops their noise radiating out onto the board power system.
All tend to be some sort of low pass filter, ranging from just putting a ceramic capacitor on each chip, relying upon the impedance of the power plane to form the low pass filter, through to rc low pass filterers , lc low pass filters up to full rlc and active filters,
The art is deciding what to do, dependent upon what the current and voltages are, what noise is on the power plane, and what noise the power pins if the ic need ,
Very little of this ever defined, the chip data sheet often has limits and psrr numbers for analog power pins.
My one advice, is trying to debug problems caused by bad filtering are very very hard to track down !
It's called HARDware cause it's not easy!
It's a great part of circuit design, trying to optimise performance , whils minimising risk, and maximising profit.
Most all chips are dc powered, and most all will require some form of local filtering ,.
The filtering does two things, smother out any noise on the incoming supply so the chip sees quieter supplies, and on noisy chips, stops their noise radiating out onto the board power system.
All tend to be some sort of low pass filter, ranging from just putting a ceramic capacitor on each chip, relying upon the impedance of the power plane to form the low pass filter, through to rc low pass filterers , lc low pass filters up to full rlc and active filters,
The art is deciding what to do, dependent upon what the current and voltages are, what noise is on the power plane, and what noise the power pins if the ic need ,
Very little of this ever defined, the chip data sheet often has limits and psrr numbers for analog power pins.
My one advice, is trying to debug problems caused by bad filtering are very very hard to track down !
It's called HARDware cause it's not easy!
