UNISONIC TECHNOLOGIES CO., LTD LR2125

UNISONIC TECHNOLOGIES CO., LTD
LR2125
LINEAR INTEGRATED CIRCUIT
300mA SELECTABLE
FIXED/ADJUSTABLE LOW
DROPOUT LINEAR REGULATOR

DESCRIPTION
As a low dropout linear regulator, the UTC LR2125 only needs low
input voltage (2.8~6V) and can deliver current to 300mA for setting
the output voltage.
The UTC LR2125 is an ideal for being used in such
battery-powered equipments notebook, personal computer and
cellular phone. Its typical dropout voltage is 230mV at loading current
300mA.
For setting the output voltage, the UTC LR2125 has two output
voltage operation modes: fixed mode senses the output voltage on
VOUT, ADJ mode needs two resistors as a voltage divider.
To protect itself against current over-loads and over
temperature, the LR2125 has current limit and thermal shutdown
functions.

FEATURES
* Operating Voltage: 2.8~6V
* Low Voltage Dropout
* Output Current Guaranteed 300mA
* For Setting Output Voltage Two Modes
– Fixed mode :Fixed Output Voltage 1~5V
– ADJ mode: Adjustable Output Voltage 0.8~5.5V
* Internal Current Limit Protection
* With Soft-Start
* Internal thermal Protection
* Work stably with Low ESR Ceramics Capacitor

ORDERING INFORMATION
Ordering Number
LR2125G-xx-AF5-R
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Copyright © 2015 Unisonic Technologies Co., Ltd
Package
SOT-25
Packing
Tape Reel
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LR2125
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LINEAR INTEGRATED CIRCUIT
MARKING INFORMATION
PACKAGE
VOLTAGE CODE
SOT-25
12: 1.2V
18: 1.8V
25: 2.5V
33: 3.3V
AD: ADJ

PIN CONFIGURATION

PIN DESCRIPTION
PIN NO
PIN NAME
1
SHDN
2
3
4
GND
VIN
VOUT
5
SET
MARKING
DESCRIPTION
Control pin for shutdown
Logic High: enable
Logic Low: shutdown
Ground
Voltage supply
Output pin
When this pin is connected to ground, turns to fixed output voltage operation.
When this pin is connected to an external resistor divider, turns to adjustable output
voltage mode operation.
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LR2125

LINEAR INTEGRATED CIRCUIT
BLOCK DIAGRAM
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LR2125
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LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATING (TA = 25°С, Unless otherwise specified)
PARAMETER
VIN Supply Voltage (VIN to GND)
SHDN
SYMBOL
VIN
VSHDN
Input Voltage ( SHDN to GND)
RATINGS
-0.3 ~ +6.5
UNIT
V
-0.3 ~ +6.5
V
Power Dissipation
PD
380
mW
Junction Temperature
TJ
-40~ +125
°С
Storage Temperature
TSTG
-65 ~ +150
°С
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.

RECOMMENDED OPERATING CONDITIONS
PARAMETER
VIN Supply Voltage
Output Voltage
VOUT Output Current
Input Capacitor
Output Capacitor
Junction Temperature

SYMBOL
VIN
VOUT
IOUT
CIN
COUT
TOPR
RATINGS
2.8 ~ 6
0.8 ~ 5.5
0 ~ 300
0.22 ~ 100
1.5 ~ 33
-40 ~ +85
UNIT
V
V
mA
μF
μF
°С
ELECTRICAL CHARACTERISTICS
(VIN = VOUT+1V (min VIN=2.8V), IOUT=0~300mA, CIN = 1μF, COUT = 2.2μF, TA = 25°С, unless otherwise specified)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN TYP MAX UNIT
Output Voltage
VOUT
0.8
5.5
V
Input Voltage
VIN
2.8
6
V
Line Regulation
∆VOUT
∆VIN × VOUT
△VOUT%/△VIN, IOUT=10mA
-0.07
+0.07
%/V
Load Regulation
∆VOUT
∆IOUT × VOUT
△VOUT%/△IOUT
-0.4
+0.4
%/A
+2
%
0.8
0.816
V
135
230
170
45
160
500
160
360
300
0.4
μA
mV
mV
dB
μVRMS
mA
V
V
1
μA
Output Voltage Accuracy
Reference Voltage
VREF
Quiescent Current
IQ
Dropout Voltage
VD
Power Supply Ripple Rejection Ratio
Output Voltage Noise
Current Limit
Shutdown Threshold
Shutdown Supply Current
PSRR
eN
ILIMIT
VIH
VIL
IOFF
VOUT Discharge MOSFET RDS(ON)
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
SET Input Threshold for
Fixed/Adjustable Output Voltage Mode
SET Input Bias Current
Soft-Start Interval
Fixed output voltage, IOUT=10mA
-2
Measured on SET, VIN=2.8V,
0.784
IOUT=10mA
IOUT =10mA ~300mA
VOUT = 2.5V, IOUT = 300mA
VOUT = 3.3V, IOUT = 300mA
f = 10kHz, IOUT = 300mA
f = 80Hz ~ 100KHz, IOUT = 300mA
400
1.6
SHDN = Low, VIN = 6V
0.1
SHDN = Low
60
Ω
160
40
°С
°С
100
mV
TSHDN
DTSHDN
-100
TSS
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650
100
60
nA
μs
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION
Input Capacitor
Value:
Larger than 1µF, at least a 1µF ceramic capacitor
Place:
Be placed near the VIN very closely
Purpose and Advantage Description:
To prevent the input rail from dropping, this capacitor can provide surge current as while as the circuit’s stepping
load transients.
Output Capacitor
Value:
Larger than 2.2µF
Place:
Be placed at the load and near the GND pin very closely.
Purpose and Advantage Description:
Mainly make sure the circuit’s operating stability. And the large value capacitor also can reduce noise and improve
transient response. Additionally, it can affect power on issue.
COUT(max) = 87  (0.55 -
0.1155
)
VOUT
Output Capacitor,COUT(µF)
Maximum Output Capacitor’s Value (µF) and the Output Voltage (V)’s Value’s Relationship
Maximum Output Capacitor’s Changing Over VOUT.
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LINEAR INTEGRATED CIRCUIT
TYPICAL APPLICATION CIRCUITS
For Fixed Output Voltage Mode
For Adjustable Output Voltage Mode
VOUT = 0.8 × (1+
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R1
)
R2
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TYPICAL CHARACTERISTICS
Quiescent Current vs. Output Current
Output Voltage vs. Input Voltage
3.0
180
IOUT=0mA
Quiescent Current, IQ(µA)
Output Voltage,VOUT (V)
2.5
2.0
IOUT=300mA
1.5
1.0
0.5
0
0
1
2
3
4
5
160
140
VIN=4.5V
100
80
60
6
VIN=5.5V
120
0
Input Voltage,VIN (V)
Dropout Voltage,VDROP(mV)
150
100
IOUT=0mA
1
2
3
4
150
200
250
300
Dropout Voltage vs. Output Current
IOUT=300mA
0
100
300
200
50
50
Output Current, IOUT(mA)
Quiescent Current vs. Input Voltage
250
Quiescent Current,IQ(µA)

LINEAR INTEGRATED CIRCUIT
5
6
250
200
150
100
50
0
0
50
100
150
200
250
Input Voltage,VIN(V)
Output Current,IOUT(mA)
Line Transient
Load Transient
CIN=1µF,COUT=2.2µF,
300
VIN=3.0V,CIN=1µF,COUT=2.2µF
VOUT
VIN
VOUT
CH1:VIN,1V/div,DC
CH2:VOUT,20mV/div,AC
Time:100µs/div
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IOUT
CH2:VOUT,50mV/div,AC
CH3:IOUT,200mA/div,DC
Time:100µs/div
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LINEAR INTEGRATED CIRCUIT
TYPICAL CHARACTERISTICS(Cont.)
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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