100mA, LOW
DROPOUT
VOLTAGE REGULATORS
OCTOBER 6, 2008
LP2950/LP2951
REV. G
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Lead Free, RoHS Compliant Packages:
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Now Available in Lead Free Packaging
UNREGULATED DC
5V @ 00mA
MAX
+
7
FEEDBACK
8
INPUT
OUTPUT
2
SENSE
+
_
FROM
CMOS OR
TTL
80kΩ
ERROR
AMPLIFIER
SHUTDOWN
0 mV
5V TAP
0kΩ
+
0kΩ
+
5
______
ERROR
+
µF
.
.
TO CMOS OR
TTL
_
+
.2V
ERROR DETECTION
COMPARATOR
REFERENCE
GROUND
Rev G
LP2950-5 Low Dropout Linear Regulators
© 2008 Exar Corporation
½
½
½
½
½
≤
≤
µ ≤
≤
≤
½
≤
≤
µ ≤
≤
≤
≤
≤
µ ≤
≤
½
µ
½
½
µ
½
µ
½
½ µ
½
µ
µ
µ
½
µ
½
µ
Rev G
LP2950-5 Low Dropout Linear Regulators
© 2008 Exar Corporation
2
LP2950/51
PARAMETER
CONDITIONS
(Note 2)
8-Pin Versions only (Continued)
LP2951AC
Min. Typ.
Max.
Min.
LP2951C
Typ. Max.
UNITS
Reference Voltage
Temperature
Coefficient
Feedback Pin Bias
Current
Temperature
Coefficient
Error Comparator
Output Leakage
Current
Output Low Voltage
Upper Threshold
Voltage
Lower Threshold
Voltage
Hysteresis
Shutdown Input
Input logic Voltage
Shut down Pin Input
Current
Regulator Output
Current in Shutdown
Thermal
Resistance
θ
JA
Low (Regulator ON)
High (Regulator OFF)
V
S
= 2.4V
V
S
= 30V
(Note 8)
8 Pin SOIC
2.0
20
0.1
50
0.1
ppm/°C
nA/°C
V
OH
= 30V
V
IN
= 4.5V
I
OL
= 400
μA
(Note 7)
(Note 7)
(Note 7)
0.01
150
40
60
75
15
1.3
30
675
3
128. 4
131.9
1
250
40
95
0.01
150
60
75
15
1
250
μA
mV
mV
95
mV
mV
0.7
50
800
10
2.0
1.3
30
675
3
0.7
50
800
10
V
V
μA
μA
μA
°C/W
3 Pin TO-92
°C/W
Note 1:
Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range.
Note 2:
Unless otherwise specified all limits guaranteed for T
J
= 25°C, V
IN
= 6V, I
L
= 100
μA
and C
L
= 1μF. Additional conditions for the 8-pin versions are feedback
tied to 5V tap and output tied to output sense (V
OUT
= 5V) and V
SHUTDOWN
≤0.8V.
Note 3:
Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes i n output voltage due to heating effects are
covered under the specification for thermal regulation.
Note 4:
Line regulation for the LP2951 is tested at I
L
= 1mA. For I
L
= 100
μA
and T
J
= 125°C, line regulation is guaranteed by design to 0.2%. See typical
performance characteristics for line regulation versus temperature and load current.
Note 5:
Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V differential. At
very low values of programmed output voltage, the minimum input supply voltage of 2V (2.3V over temperature) must be taken into account.
Note 6:
V
REF
≤V
OUT
≤(V
IN
- 1V), 2.3
≤V
IN
≤30V,
100μA≤I
L
≤100mA,
T
J
≤T
JMAX
.
Note 7:
Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nomi nal reference voltage measured at 6V input. To
express these thresholds in terms of output voltage change, multiply by the error amplifier gain = V
OUT
/V
REF
= (R
1
+ R
2
)/R
2
. For example, at a programmed output
voltage of 5V, the error output is guaranteed to go low when the output drops by 95 mV x 5V/1.235 = 384 mV. Thresholds remain constant as a percent of V
OUT
as V
OUT
is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.
Note 8:
V
SHUTDOWN
≥2V,
V
IN
≤30V,
V
OUT
=0, Feedback pin tied to 5V Tap.
Note 9:
All typical values are not guaranteed. The value could vary from lot to lot.
Rev G
LP2950-5 Low Dropout Linear Regulators
© 2008 Exar Corporation
3
6
5
OUTPUT VOLTAGE (VOLTS)
INPUT CURRENT (µA)
250
225
GROUND PIN CURRENT (mA)
10
200
175
150
125
100
R
L
= 50k
Ω
4
R
L
=
1
3
R
L
=50kΩ
8
2
1
0
0
1
2
3
4
5
6
INPUT VOLTAGE (VOLTS)
R
L
=
75
50
25
8
0.1
0
0
1
2
3
4
5
6 7
8
9 10
0.01
0.1
1
10
100
INPUT VOLTAGE (VOLTS)
LOAD CURRENT (mA)
Dropout Characteristics
Input Current
Quiescent Current
320
280
GROUND CURRENT (µA)
INPUT CURRENT (mA)
240
200
160
I
L
= 0
I
L
= 1mA
120
80
40
0
0
1
2
3
4
5
6
7
8
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
5
6
16
GROUND CURRENT (mA)
R
L
=50
Ω
V
OUT
= 5V
12
V
IN
= 6V
I
L
= 100mA
8
4
INPUT VOLTAGE (VOLTS)
7
8
9 10
-75 -50 -25
0
25 50 75 100 125 150
INPUT VOLTAGE (VOLTS)
TEMPERATURE (ºC)
Ground Current
16
14
Input Current
190
Ground Current
QUIESCENT CURRENT (µA)
GROUND CURRENT (mA)
12
I
L
=100mA
170
V
IN
=6V
I
L
=100uA
10
8
6
4
2
0
150
130
0
1
2
3
4
5
6
7
8
-75 -50 -25
0
25 50 75 100 125 150
INPUT VOLTAGE
TEMPERATURE (ºC)
Ground Current
Quiescent Current
Rev G
LP2950-5 Low Dropout Linear Regulators
© 2008 Exar Corporation
4
600
I
L
= 100mA
SHORT CIRCUIT CURRENT (mA)
500
170
160
500
DROP-OUT VOLTAGE (mV)
DROP-OUT VOLTAGE (mV)
400
150
140
400
300
~
~
300
200
T
J
= 25ºC
130
120
100
50
0
-75 -50 -25
0
25 50 75 100 125 150
TEMPERATURE (ºC)
I
L
= 100
µA
100
0
100µA
1mA
10mA
100mA
OUTPUT CURRENT
110
110
-75 -50 -25
0
25 50 75 100 125 150
TEMPERATURE (ºC)
Drop-Out Voltage
8
V
OUT
= 5V
Drop-Out Voltage
2.5
T
A
= 125ºC
Short Circuit Current
100
mV
50
mV
INPUT OUTPUT VOLTAGE
VOLTAGE CHANGE
6
COMPARATOR OUTPUT (V)
2.0
SINK CURRENT (mA)
4
HYSTERESIS
0
-50
mV
~
~
8V
6V
4V
0
200
400
TIME(µs)
C
L
= 1
µF
I
L
= 1mA
V
OUT
= 5V
1.5
T
A
= 25ºC
2
0
-2
0
1
PULLUP RESISTOR TO
SEPARATE 5V SUPPLY
1.0
T
A
= -55ºC
0.5
0.0
2
3
4
5
INPUT VOLTAGE (V)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
OUTPUT LOW VOLTAGE (V)
600
800
Error Comparator Output
10
I
O
= 100
µA
OUTPUT IMPEDANCE (OHMS)
LP2951 Comparator Sink Current
90
80
RIPPLE REJECTION (dB)
Line Transient Response
90
80
RIPPLE REJECTION (dB)
5
2
1
0.5
0.2
0.1
0.05
0.02
0.01
10
100
1K
10K
100K
1M
FREQUENCY (Hz)
I
O
= 1mA
I
O
= 100mA
70
I
L
= 0
70
60
50
40
30
I
L
= 1mA
C
L
= 1µF
V
IN
= 6V
V
OUT
= 5V
60
50
40
C
L
= 1
µF
V
IN
= 6V
V
OUT
= 5V
V
OUT
= 5V
C
L
= 1
µF
I
L
= 100
µA
30
20
10
1
20
I
L
= 10mA
10
2
10
3
10
4
10
5
10
6
10
1
10
2
10
3
10
4
10
5
10
6
FREQUENCY (Hz)
FREQUENCY (Hz)
Output Impedance
Ripple Rejection
Ripple Rejection
Rev G
LP2950-5 Low Dropout Linear Regulators
© 2008 Exar Corporation
5
