EV8801DJ-00A 查看數據表（PDF） - Monolithic Power Systems
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EV8801DJ-00A Datasheet PDF : 7 Pages
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MP8801 – LOW DROPOUT, 150mA LINEAR REGULATOR
APPLICATION INFORMATION
SETTING THE OUTPUT VOLTAGE
The fixed output voltage of the MP8801DJ is set
to 2.5V, 2.85V or 3.3V, depending on the
internal resistor divider (Figure 1). You can also
adjust the output voltage by using an external
resistor divider (R1 and R2 in Figure 2).
However, the sum of R1 and R2 should not
exceed 100kΩ in order to minimize the impact
of the internal resistor divider. For an accurate
output-voltage setting, use 10kΩ (±1%) for the
low-side resistor R2 of the voltage divider, while
the high-side resistor R1 can be determined by
the equation:
R1
=
R2
×
⎜⎜⎝⎛
VOUT −
VFB
VFB
⎟⎟⎠⎞
Where VFB is the OUT feedback threshold
voltage equal to 1.222V.
Example: For 2.5V Output
R1 = 2.5V − 1.222V = 10.41kΩ
⎜⎛ 1.222V ⎟⎞
⎝ 10kΩ ⎠
You can select a standard 10.5kΩ (±1%)
resistor for R1.
The following table lists the selected R1 values
for some typical output voltages:
Table 1—Adjustable Output Voltage R1 Values
VOUT (V)
1.25
1.5
1.8
2
2.5
2.8
3
3.3
4
5
R1 (Ω)
232
2.26k
4.75k
6.34k
10.5k
13k
14.7k
16.9k
22.6k
30.9k
R2 (Ω)
10k
In Figures 3 and 4, C2 is added for an improved
transient response.
INPUT CAPACITOR SELECTION
For proper operation, place a ceramic capacitor
(C1) between 1µF and 10µF of dielectric type
X5R or X7R between the input pin and ground.
Larger values in this range will help improve
line transient response at the drawback of
increased size.
OUTPUT CAPACITOR SELECTION
For stable operation, use a ceramic capacitor
(C3) of type X5R or X7R between 1µF and
10µF. Larger values in this range will help
improve load transient response and reduce
noise with the drawback of increased size.
Output capacitors of other dielectric types may
be used, but are not recommended as their
capacitance can deviate greatly from their rated
value over temperature.
To improve load transient response, add a
small ceramic (X5R, X7R or Y5V dielectric)
100nF feed forward capacitor in parallel with
R1. The feed forward capacitor is not required
for stable operation.
MP8801 Rev. 1.7
www.MonolithicPower.com
5
10/3/2006
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
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