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PDF LR8801 Data sheet ( Hoja de datos )
| Número de pieza | LR8801 | |
| Descripción | Low Dropout 150mA Linear Regulator | |
| Fabricantes | LRC | |
| Logotipo |  |
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LESHAN RADIO COMPANY, LTD.
Low Dropout
150mA Linear Regulator
LR8801
DESCRIPTION
The LR8801 is a low-noise, low-dropout linear
regulator. It operates from a 2.7V to 6.5V input
voltage and regulates the output voltage with
2% accuracy at 2.5V, 2.85V or 3.3V. The
internally set output voltage may be overridden
with an external resistor divider from 1.25V to
5V.
The LR8801 can supply up to 150mA of load
current. The LR8801 features thermal overload
protection and is available in a 5-pin TSOT23-5
package.
FIXED VOLTAGE PART NUMBERS
Part Number
Output Voltage
LR8801DJ –2.5
LR8801DJ –2.85
LR8801DJ –3.3
2.5V
2.85V
3.3V
EVALUATION BOARD REFERENCE
Board Number Output*
Dimensions
LR8801DJ-00A 2.85V 2.0”X x 2.0”Y x 0.4”Z
*
Default output voltage adjustable from 1.25V to 5.0V using an
external resistor divider.
FEATURES
• Low 100mV Dropout at 100mA Output
• 2% Accurate Output Voltage
• Fixed Output Voltage Options of 2.5V,
2.85V or 3.3V
• Adjustable Output Voltage from 1.25V to 5V
using an External Resistor Divider
• Up to 6.5V Input Voltage
• High PSRR
o 70dB at 1KHz
o 30dB at 1MHz
• Better Than 0.001%/mA Load Regulation
• Stable With Low-ESR Output Capacitor
• Low 125µA Ground Current
• Internal Thermal Protection
APPLICATIONS
• 802.11 PC Cards
• Mobile Handset PLL Power
• Audio Codec Power
TYPICAL APPLICATION
VIN
2.7V to 6.5V
1 IN
OUT 5
LR8801DJ-X.X
VIN 3 EN GND FB 4
EN (Pin3)
2
may be connected
to IN (Pin 1) directly
R1
The sum of
R2
R1 and R2
should not
exceed 100k
OUTPUT
1.5V to 5V
VDROPOUT vs ILOAD
160
140
120
100
80
60
40
20
0
0 20 40 60 80 100 120 140 160
ILOAD (mA)
1/7
1 page  
APPLICATION INFORMATION
SETTING THE OUTPUT VOLTAGE
The fixed output voltage of the LR8801DJ 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
⎜⎛
⎝
1.222V
10kΩ
⎟⎞
⎠
= 10.41kΩ
You can select a standard 10.5k (±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.
LESHAN RADIO COMPANY, LTD.
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.
5/7
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| Páginas | Total 7 Páginas | |
| PDF Descargar | [ Datasheet LR8801.PDF ] | |
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