LP5952TL-1.5/NOPB National Semiconductor, LP5952TL-1.5/NOPB Datasheet - Page 12

• Manufacturer Part Number: LP5952TL-1.5/NOPB
• Description: IC REG LDO 1.5V 350MA 5MICROSMD
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LP5952TL-1.5/NOPB

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.5V
• Voltage - Input: Up to 4.5V
• Voltage - Dropout (typical): 0.088V @ 350mA
• Number Of Regulators: 1
• Current - Output: 350mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 5-MicroSMD
• For Use With: LP5952TL-1.5EV - BOARD EVALUATION LP5952TL-1.5
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Other names: LP5952TL-1.5TR

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INPUT CAPACITOR
If the LP5952 is used stand alone, an input capacitor at V
required for stability. It is recommended that a 1.0µF capacitor
be connected between the LP5952 power voltage input pin
V
without limit).
This capacitor must be located a distance of not more than 1
cm from the V
Any good quality ceramic, tantalum, or film capacitor may be
used at the input.
A capacitor at V
ply does not exceed 5cm.
If the device is used in the typical application as post regulator
after a DC-DC regulator, no input capacitors are required at
all as the capacitors of the DC-DC regulator (C
are sufficient if both components are mounted close to each
other and a proper GND plane is used. If the distance between
the output capacitor of the DC-DC regulator and the V
of the LP5952 is larger than 5cm, it's recommended to add
the mentioned input capacitor at V
Important: Tantalum capacitors can suffer catastrophic fail-
ures due to surge current when connected to a low-
impedance source of power (like a battery or a very large
capacitor). If a tantalum capacitor is used at the input, it must
be guaranteed by the manufacturer to have a surge current
rating sufficient for the application.
The ESR (Equivalent Series Resistance) of the input capac-
itor should be in the range of 3mΩ to 300mΩ. The tolerance
and temperature coefficient must be considered when select-
ing the capacitor to ensure the capacitance will remain
470nF over the entire operating temperature range.
OUTPUT CAPACITOR
The LP5952 is designed specifically to work with very small
ceramic output capacitors. A ceramic capacitor (dielectric
types X7R, Z5U, or Y5V) in the 2.2µF range (up to 10µF) and
with an ESR between 3mΩ to 300mΩ is suitable as C
the LP5952 application circuit.
This capacitor must be located a distance of not more than
1cm from the V
ground.
It is also possible to use tantalum or film capacitors at the
device output, V
sons of size and cost (see the section Capacitor Character-
istics).
CAPACITOR CHARACTERISTICS
The LP5952 is designed to work with ceramic capacitors on
the output to take advantage of the benefits they offer. For
capacitance values in the range of 1µF to 4.7µF, ceramic ca-
pacitors are the smallest, least expensive and have the lowest
ESR values, thus making them best for eliminating high fre-
quency noise. The ESR of a typical 1µF ceramic capacitor is
in the range of 3mΩ to 40mΩ, which easily meets the ESR
requirement for stability for the LP5952.
For both input and output capacitors, careful interpretation of
the capacitor specification is required to ensure correct device
operation. The capacitor value can change greatly, depend-
ing on the operating conditions and capacitor type.
In particular, the output capacitor selection should take ac-
count of all the capacitor parameters, to ensure that the
specification is met within the application. The capacitance
can vary with DC bias conditions as well as temperature and
frequency of operation. Capacitor values will also show some
decrease over time due to aging. The capacitor parameters
IN
and ground (this capacitance value may be increased
IN
BATT
pin and returned to a clean analogue ground.
OUT
OUT
, but these are not as attractive for rea-
is not required if the distance to the sup-
pin and returned to a clean analogue
IN
.
IN
and C
OUT
IN
OUT
IN
pin
in
is
≥
)
12
are also dependant on the particular case size, with smaller
sizes giving poorer performance figures in general. The ex-
ample shows a typical graph comparing different capacitor
case sizes in a Capacitance vs. DC Bias plot. As shown in the
graph, increasing the DC Bias condition can result in the ca-
pacitance value falling below the minimum value given in the
recommended capacitor specifications table (0.47/1.5µF in
this case). Note that the graph shows the capacitance out of
spec for the 0402 case size capacitor at higher bias voltages.
It is therefore recommended that the capacitor manufactur-
ers’ specifications for the nominal value capacitor are con-
sulted for all conditions, as some capacitor sizes (e.g. 0402)
may not be suitable in the actual application.
The ceramic capacitor’s capacitance can vary with tempera-
ture. The capacitor type X7R, which operates over a temper-
ature range of -55°C to +125°C, will only vary the capacitance
to within ±15%. The capacitor type X5R has a similar toler-
ance over a reduced temperature range of -55°C to +85°C.
Many large value ceramic capacitors, larger than 1µF are
manufactured with Z5U or Y5V temperature characteristics.
Their capacitance can drop by more than 50% as the tem-
perature varies from 25°C to 85°C. Therefore X7R is recom-
mended over Z5U and Y5V in applications where the ambient
temperature will change significantly above or below 25°C.
Tantalum capacitors are less desirable than ceramic for use
as output capacitors because they are more expensive when
comparing equivalent capacitance and voltage ratings in the
1µF to 4.7µF range.
Another important consideration is that tantalum capacitors
have higher ESR values than equivalent size ceramics. This
means that while it may be possible to find a tantalum capac-
itor with an ESR value within the stable range, it would have
to be larger in capacitance (which means bigger and more
costly) than a ceramic capacitor with the same ESR value. It
should also be noted that the ESR of a typical tantalum will
increase about 2:1 as the temperature goes from 25°C down
to -40°C, so some guard band must be allowed.
NO-LOAD STABILITY
The LP5952 will remain stable and in regulation with no ex-
ternal load. This is an important consideration in some cir-
cuits, for example CMOS RAM keep-alive applications.
FIGURE 4. Graph Showing A Typical Variation In
Capacitance vs DC Bias
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