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Q: TPS62262 verus TPS62260 Vout tolerance by 1038028
The d/s for these parts gives a tolerance for the FB pin voltage.
What then is the tolerance on Vout for the fixed output 1V2 device? Is it +/-1.5%?
In that case, what is the tolerance on Vout for the adjustable output version TPS62260, where there are no internal resistors on the FB pin?
I'm trying to sort out what is the tolerance due to the Vref only (applies to both the adj and fixed output versions) and what is the tolerance due to the internal FB divider (applies to fixed output versions only).
The bottom line is this: customer is calculating the Vout tolerance over temperature to make sure he is still in spec. If you use external 1% tol resistor divider for FB, then they can have a tolerance in reality of +/-2.5% over time and temperature. So it would be nice to be able to calculate how much improvement can be achieved if he swapped to the fixed Vout version.
A: Re: TPS62262 verus TPS62260 Vout tolerance by 1090425
Essentially, these parts achieve the same FB voltage accuracy for the adjustable and fixed versions. With the fixed versions, the FB pin is directly connected to Vout and so the tolerance of FB is the tolerance of Vout. That is what the test conditions on the FB accuracy spec mean:
for fixed output voltage versions VFB = VOUT,
So, the fixed voltage versions remove the inaccuracy of the FB resistors from the equation.
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