SPX3819M5-L-1-5 Datasheet, PDF (7/12 Pages) Exar Corporation – GENERAL DESCRIPTION

SPX3 8 1 9
500m A Low -Noise LDO Volt age Regulat or
Fig. 15 Output Noise vs Bypass Capacitor Value IL = 10mA,
10Hz - 100kHz
Fig. 16 Line Transient Response for 3.3V Device
Fig. 17 Load Transient Response for 3.3V Device
APPLICATION INFORMAT ION
but the same stability often can
be obtained
The SPX3819 requires an output capacitor for
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device stability. Its value depends upon the
With the SPX3819 adjustable version, the
application circuit. In general, linear regulator
minimum value of output capacitance is a
stability decreases with higher output
function of the output voltage. The value
currents. In applications where the SPX3819 is
decreases with higher output voltages, since
sourcing less current, a lower
output
closed loop gain is increased.
capacitance may be sufficient. For example, a
regulator outputting
only 10mA, requires
TYPICAL A PPLICATIONS CI RCUITS
approximately half the capacitance as the
same regulator sourcing 150mA.
A 10nF capacitor on the BYP pin will
significantly reduce output noise, but it may
Bench testing is the best method for
be left unconnected if the output noise is not a
determining the proper type and value of the
major concern. The SPX3819 start - up speed is
capaci tor since the high frequency
inversely proportional to the size of the BYP
characteristics of electrolytic capacitors vary
capacitor. Applications re quiring a slow
widely, depending on type and manufacturer.
rampup of the output voltage should use a
$ KLJK TXDOLW\ eleNjctr)olyticDOXPlaLrgQerXCPBYP. However, if a rapid turn - on is
capacitor works in most application
circuits,
necessary, the BYP capacitor can be omitted.
© 2012 Exar Corporation
7/ 12
Rev. 2.0.0