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OCTOBER 6, 2008
100mA, LOW DROPOUT VOLTAGE REGULATORS
LP2950/LP2951
REV. G
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Now Available in Lead Free Packaging
UNREGULATED DC
+
7
FEEDBACK
8
INPUT
OUTPUT
FROM
CMOS OR
TTL
SHUTDOWN
+
_
ERROR
AMPLIFIER
80kΩ
0 mV
+
+
0kΩ
_ ERROR DETECTION
+ .2V
COMPARATOR
REFERENCE
2
SENSE
5V TAP
5
______
ERROR
GROUND
5V @ 00mA
MAX
0kΩ
+
µF
.
.
TO CMOS OR
TTL
Rev G
LP2950-51 Low Dropout Linear Regulator
© 2008 Exar Corporation
600
IL= 100mA
500
400
300
~
~
100
50 IL= 100 µA
0
-75 -50 -25 0 25 50 75 100 125 150
TEMPERATURE (ºC)
Drop-Out Voltage
500
400
300
200
TJ = 25ºC
100
0
100µA
1mA 10mA
OUTPUT CURRENT
Drop-Out Voltage
170
160
150
140
130
120
110
100mA
110
-75 -50 -25 0 25 50 75 100 125 150
TEMPERATURE (ºC)
Short Circuit Current
8
VOUT = 5V
6
4
HYSTERESIS
2
0
PULLUP RESISTOR TO
-2 SEPARATE 5V SUPPLY
0 12 3 4
INPUT VOLTAGE (V)
Error Comparator Output
5
2.5 100
mV
2.0
TA = 125ºC
50
mV
0
1.5
1.0
TA = 25ºC
-50
mV ~~
CL= 1 µF
IL= 1mA
VOUT = 5V
8V
TA = -55ºC
0.5 6V
0.0 4V
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0 200 400 600 800
OUTPUT LOW VOLTAGE (V)
TIME(µs)
LP2951 Comparator Sink Current
Line Transient Response
10
IO= 100 µA
5
2 IO= 1mA
1 IO= 100mA
0.5
0.2 VOUT = 5V
CL= 1 µF
0.1
0.05
0.02
0.01
10 100 1K 10K 100K
FREQUENCY (Hz)
Output Impedance
1M
90 90
80
70
IL= 0
60
80
70 IL = 1mA
60
CL= 1µF
VIN= 6V
VOUT = 5V
50 50
40
CL= 1 µF
30 VIN= 6V
VOUT = 5V
20
IL= 100 µA
10 1 10 2 10 3 10 4 10 5 10 6
FREQUENCY (Hz)
Ripple Rejection
40
30
20
10 1
IL = 10mA
10 2 10 3 10 4
FREQUENCY (Hz)
10 5
Ripple Rejection
10 6
Rev G
LP2950-5 Low Dropout Linear Regulators
© 2008 Exar Corporation
+V IN
AUX SHUTDOW
INPUT
ON
OFF
8
SD
+V IN _______ 5
ERROR
LP295
0K Ω.
5 DEGR.EE SHUTDOWN FLAG
V OUT
+
TEMP AS5
SENSOR
-
GND
FB
7
8.2K Ω
EXTERNAL CIRCUIT
PROTECTED FROM
OVER TEMPERATURE
(V+ GOES OFF WHEN
TEMP > 25)
OR
RELAY
20mA
N00
0.µF
+5V
.7mA
8
+V IN
V OUT
LP295
7
FB
OUTPUT
2
GND
0K Ω
N57
MIN VOLTAGE = V
UNREGULATED INPUT
8
IN
0KΩ
V OUT
LP295
27KΩ
2N52
(2)
V TAP
FB
7
2
SENSE
GND
+ .7µF
5V
OUTPUT
LOAD
50mA
TO
00 mA
042408 Rev F
LP2950-51 Low Dropout Linear Regulator
11
© 2008 Exar Corporation