Hello,
We're trying to do some error analysis on the LP2950-50LPRE3 and having trouble interpreting the line regulation parameter from the datasheet. Our main question is whether line regulation should be expressed as %/V as in the Section 6.5 electrical characteristics or whether it should be an absolute percentage.
Line regulation is specified as %/V in Section 6.5, while Load regulation is specified as an absolute percentage.
However, in the front matter and in Section 7.1, both line regulation and load regulation are listed together as absolute percentages.
Also please confirm the text from Section 7.1 are incorrect: these should be 0.03 and 0.04 typical, not 0.3 and 0.4 typical.
Figure 30 shows output voltage change due to line regulation. Input voltage in Figure 30 seems to vary from 6V to 30V, so we're guessing this is the 5V version of the LP2950 due to the Vin condition in Section 6.5, even though Figure 30 doesn’t say which regulator version it applies to.
The slope of the line is approximately 4.5mV / 24V = 187.5µV/V. If line regulation is really in %/V units, this is 0.00375%/V for the 5V regulator—almost an order of magnitude below the typical line regulation value from Section 6.5. If line regulation is really in absolute percentage units, this is 0.09% for the 5V regulator, which is at least between the 0.03% typical value and the 0.2% maximum value at 25°C.
Thanks very much, Keith
