LP3995ILD-1.6 National Semiconductor, LP3995ILD-1.6 Datasheet - Page 12

• Manufacturer Part Number: LP3995ILD-1.6
• Description: Micropower 150mA CMOS Voltage Regulator with Active Shutdown
• Manufacturer: National Semiconductor

www.national.com
Application Hints
The types of capacitors best suited for the noise bypass
capacitor are ceramic and film. High quality ceramic capaci-
tors with NPO or COG dielectric typically have very low
leakage. Polypropolene and polycarbonate film capacitors
are available in small surface-mount packages and typically
have extremely low leakage current.
Unlike many other LDO’s, the addition of a noise reduction
capacitor does not effect the transient response of the de-
vice.
ENABLE OPERATION
The LP3995 may be switched ON or OFF by a logic input at
the ENABLE pin, V
device on. When the enable pin is low, the regulator output is
off and the device typically consumes 3 nA. If the application
does not require the shutdown feature, the V
be tied to V
To ensure proper operation, the signal source used to drive
the V
specified turn-on/off voltage thresholds listed in the Electrical
Characteristics section under V
FAST TURN OFF AND ON
The controlled switch-off feature of the device provides a fast
turn off by discharging the output capacitor via an internal
FET device. This discharge is current limited by the RDSon
of this switch. Fast turn-on is guaranteed by control circuitry
EN
input must be able to swing above and below the
IN
to keep the regulator output permanently on.
EN
. A high voltage at this pin will turn the
IL
(Continued)
and V
IH
.
EN
pin should
12
within the reference block allowing a very fast ramp of the
output voltage to reach the target voltage.
micro SMD MOUNTING
The micro SMD package requires specific mounting tech-
niques which are detailed in National Semiconductor Appli-
cation Note AN-1112.
Referring to the section Surface Mount Technology (SMT)
Assembly Considerations, it should be noted that the pad
style which must be used with the 5 pin package is NSMD
(non-solder mask defined) type.
For best results during assembly, alignment ordinals on the
PC board may be used to facilitate placement of the micro
SMD device.
micro SMD LIGHT SENSITIVITY
Exposing the micro SMD device to direct sunlight will cause
incorrect operation of the device. Light sources such as
halogen lamps can affect electrical performance if they are
situated in proximity to the device.
Light with wavelengths in the red and infra-red part of the
spectrum have the most detrimental effect thus the fluores-
cent lighting used inside most buildings has very little effect
on performance. Tests carried out on a micro SMD test
board showed a negligible effect on the regulated output
voltage when brought within 1 cm of a fluorescent lamp. A
deviation of less than 0.1% from nominal output voltage was
observed.