pt5109 China Resources Powtech (Shanghai) Co., Ltd, pt5109 Datasheet - Page 7

• Manufacturer Part Number: pt5109
• Description: High-psrr 300ma Ldo
• Manufacturer: China Resources Powtech (Shanghai) Co., Ltd

APPLICATION INFORMATION
INPUT CAPACITOR
An input capacitor of ≥ 1.0μF is required between the
PT5109 V
located within 1cm distance from V
connected to a clear ground. A ceramic capacitor is
recommended although a good quality tantalum or film
may be used at the input. However, a tantalum
capacitor can suffer catastrophic failures due to surge
current when connected to a low impedance power
supply (such as a battery or a very large capacitor).
There is no requirement for the ESR on the input
capacitor, but tolerance and temperature coefficient
must be considered in order to ensure the capacitor
work within the operation range over the full range of
temperature and operating conditions.
OUTPUT CAPACITOR
In applications, it is important to select the output
capacitor to keep the PT5109 in stable operation. The
output capacitor must meet all the requirements
specified in the following recommended capacitor table
over all conditions in applications. The minimum
capacitance for stability and correct operation is 0.6μF.
The capacitance tolerance should be ±30% or better
over
recommended capacitor type is X7R to meet the full
device temperature specification.
The capacitor application conditions also include
DC-bias,
operation will result if the capacitance drops below
minimum specified value (see the next section
Capacitor Characteristics).
The PT5109 is designed to work with very small
ceramic output capacitors. A 1.0μF capacitor (X7R type)
with ESR type between 0 and 400mΩ is suitable in the
PT5109 applications. X5R capacitors may be used but
have a
other capacitor types (Y5V, Z6U) that may be used,
selection relies on the range of operating conditions and
China Resources Powtech (Shanghai) Limited
PT5109_DS Rev EN_2.0
Capacitance
ESR
Recommended Output Capacitor (C
the
narrow temperature range. With these and
IN
frequency
and GND pin. This capacitor must be
operation
TYP
1.0
and
temperature
MIN
0.6
0
temperature.
MAX
400
10
range.
IN
OUT
pin and
Unstable
)
Unit
mΩ
μF
The
WWW.CRPOWTECH.COM
temperature range for a specified application.
It may also be possible to use tantalum or film
capacitors at the output, but these are not as good for
reasons of size and cost.
It is also recommended that the output capacitor be
located within 1cm from the output pin and return to a
clean ground wire.
CAPACITOR CHARACTERISTICS
The PT5109 is designed to work with ceramic capacitor
on the output to take advantage of the benefit they offer:
for capacitor values from 1.0μF to 4.7uF range, ceramic
capacitors are the smallest, least expensive and have the
lowest ESR values (which is good for eliminating high
frequency noise). The ESR of a typical 1uF ceramic
capacitor is in the range of 20mΩ to 40mΩ that easily
satisfies the ESR requirement for stability by the
PT5109.
For
understanding the capacitor specifications is required to
ensure correct device operation. The capacitor value
can change greatly because of the operating condition
and capacitor type. In particular the output capacitor
selection should take account of all the capacitor
parameters to ensure that the specification is satisfied
for the application. Capacitor values can vary with DC
bias conditions, temperature, and frequency of
operation. Capacitor values will also demonstrate some
decrease over time due to aging. The capacitor
parameters are also dependant on the particular case
size with smaller size giving poorer performance
figures on general.
As an example, the following figure shows a typical
graph showing a comparison of capacitor case sizes in
Capacitance vs. DC Bias plot. As shown in the graph,
as a result of the DC bias condition the capacitance
value may drop below the minimum capacitance value
given in the recommended capacitor table. It is also
recommended
specification for the normal value
consulted for all conditions as some capacitor sizes may
not be suitable in the actual application.
both
High-PSRR 300mA LDO
input
that
and
the
output
capacitor
PT5109
capacitors
capacitor are
manufacture’s
careful
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