LP2987, LP2988
SNVS004J –MARCH 1999–REVISED APRIL 2013
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BYPASS CAPACITOR (LP2988)
The capacitor connected to the Bypass pin must have very low leakage. The current flowing out of the Bypass
pin comes from the Bandgap reference, which is used to set the output voltage. Since the Bandgap circuit has
only a few microamps flowing in it, loading effects due to leakage current will cause a change in the regulated
output voltage.
Curves are provided which show the effect of loading the Bypass pin on the regulated output voltage.
Care must be taken to ensure that the capacitor selected for bypass will not have significant leakage current over
the operating temperature range of the application.
A high quality ceramic capacitor which uses either NPO or COG type dielectiric material will typically have very
low leakage. Small surface-mount polypropolene or polycarbonate film capacitors also have extremely low
leakage, but are slightly larger in size than ceramics.
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