NSC LP4951CMX, LP4951CM Datasheet
LP4950C-5V and LP4951C
Adjustable Micropower Voltage Regulators
General Description
The LP4950C and LP4951C are micropower voltage regulators with very low quiescent current (75µA typ.) and very
low dropout voltage (typ. 40mV at light loads and 380mV at
100mA). They are ideally suited for use in battery-powered
systems. Furthermore, the quiescent current of the
LP4950C/LP4951C increases only slightly in dropout, prolonging battery life.
The LP4950C in the popular 3-pin TO-92 package is pin
compatible with older 5V regulators. The 8-lead LP4951C is
available in a plastic surface mount package and offers
additional system functions.
One such feature is an error flag output which warns of a low
output voltage, often due to falling batteries on the input. It
may be used for a power-on reset. A second feature is the
logic-compatible shutdown input which enables the regulator
to be switched on and off. Also, the part may be pin-strapped
for a 5V output or programmed from 1.24V to 29V with an
external pair of resistors.
Careful design of the LP4950C/LP4951C has minimized all
contributions to the error budget. This includes a tight initial
tolerance (.5% typ.), extremely good load and line regulation
(.05% typ.) and a very low output voltage temperature coefficient, making the part useful as a low-power voltage reference.
Features
n High accuracy 5V guaranteed 100mA output
n Extremely low quiescent current
n Low dropout voltage
n Extremely tight load and line regulation
n Very low temperature coefficient
n Use as Regulator or Reference
n Needs only 1µF for stability
n Current and Thermal Limiting
LP4951C versions only
n Error flag warns of output dropout
n Logic-controlled electronic shutdown
n Output programmable from 1.24 to 29V
Block Diagram and Typical
Applications
LP4950C LP4951C
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20052801
September 2002
LP4950C-5V and LP4951C Adjustable Micropower Voltage Regulators
© 2002 National Semiconductor Corporation DS200528 www.national.com
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Input Supply Voltage −0.3 to +30V
SHUTDOWN Input Voltage,
Error Comparator Output
Voltage, (Note 9)
−0.3 to +30V
FEEDBACK Input Voltage −1.5 to +30V
(Note 9) (Note 10)
Power Dissipation Internally Limited
Junction Temperature (T
J
) +150˚C
Ambient Storage Temperature −65˚ to +150˚C
Soldering Dwell Time, Temperature
Wave
Infrared
Vapor Phase
4 seconds, 260˚C
10 seconds, 240˚C
75 seconds, 219˚C
ESD TBD
Operating Ratings (Note 1)
Maximum Input Supply Voltage 30V
Junction Temperature Range
(Note 8)
LP4950C, LP4951C −40˚C to 125˚C
Electrical Characteristics (Note 2)
Parameter
Conditions
(Note 2)
LP4950CZ
Units
LP4951CM
Tested Design
Typ Limit Limit
(Note 3) (Note 4)
Output Voltage T
J
= 25˚C 5.0 5.1 V max
4.9 V min
−25˚C ≤ T
J
≤ 85˚C 5.15 V max
4.85 V min
Full Operating 5.2 V max
Temperature Range 4.8 V min
Output Voltage 100 µA ≤ I
L
≤ 100 mA 5.24 V max
T
J
≤ T
JMAX
4.76 V min
Output Voltage
Temperature Coefficient
(Note 12) 150 ppm/˚C
Line Regulation
(Note 14)
6V ≤ V
IN
≤ 30V (Note 15) 0.04 0.2 % max
0.4 % max
Load Regulation
(Note 14)
100µA ≤ I
L
≤ 100mA 0.1 0.2 % max
0.3 % max
Dropout Voltage
(Note 5)
I
L
= 100µA 50 80 mV max
150 mV max
I
L
= 100mA 380 450 mV max
600 mV max
Ground Current I
L
= 100µA 75 150 µA max
170 µA max
I
L
= 100mA 8 15 mA max
19 mA max
Dropout Ground Current V
IN
= 4.5V 110 200 µA max
I
L
= 100µA 230 µA max
Current Limit V
OUT
= 0 160 200 mA max
220 mA max
Thermal Regulation (Note 13) 0.05 0.2 %/W max
Output Noise, C
L
= 1µF 430 µV rms
10 Hz to 100 kHz C
L
= 200µF 160 µV rms
C
L
= 3.3µF (Bypass = 0.01µF
Pins 7 to 1 (LP4951C)
100 µV rms
LP4950C-5V and LP4951C
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Electrical Characteristics
LP4951C
Parameter Conditions (Note 2) Typ Tested
Limit (Note
3)
Desgin
Limit (Note
4)
Units
8-PIN VERSIONS ONLY
Reference Voltage 1.235 1.285 V max
1.295 V max
1.185 V min
1.165 Vmin
Reference Voltage (Note 7) 1.335 V max
1.135 V min
Feedback Pin Bias
Current
20 40 nA max
60 nA max
Reference Voltage
Temperature Coefficient
(Note 12) 50 ppm/˚C
Feedback Pin Bias
Current Temperature
Coefficient
0.1 nA/˚C
Error Comparator
Output Leakage Current VOH = 30V 0.01 1 µA max
2 µA max
Output Low Voltage V
IN
= 4.5V
I
OL
= 400µA
150 250 mV max
400 mV max
Upper Threshold Voltage (Note 4) 60 40 mV min
25 mV min
Lower Threshold Voltage (Note 6) 75 95 mV max
140 mV max
Hysteresis (Note 6) 15 mV
Shutdown Input
Input Logic Voltage 1.3 V
Low (Regulator ON) 0.7 V max
High (Regulator OFF) 2.0 V min
Shutdown Pin Input
Current
V
SHUTDOWN
= 2.4V 30 50 µA max
100 µA max
V
SHUTDOWN
= 30V 450 600 µA max
750 µA max
Regulator Output Current
in Shutdown
(Note 11) 3 10 µA max
20 µA max
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device
is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical
Characteristics tables.
Note 2: Unless otherwise specified all limits guaranteed for V
IN
=6V,IL= 100µA and CL= 1µF. Limits appearing in boldface type apply over the entire junction
temperature range for operation. Limits appearing in normal type apply for T
A=TJ
= 25˚C. Additional conditions for the 8-pin versions are FEEDBACK tied to V
TAP
,
OUTPUT tied to SENSE (V
OUT
= 5V), and V
SHUTDOWN
≤ 0.8V.
Note 3: Guaranteed and 100% production tested.
Note 4: Guaranteed but not 100% production tested. These limits are not used to calculate outgoing AQL levels.
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: Comparator thresholds are expressed in terms of a voltage differential at the Feedback terminal below the nominal reference voltage measured at V
IN
=
6V. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = V
OUT/VREF
= (R1 + R2)/R2.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/1.235V = 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 7: V
REF
≤ V
OUT
≤ (VIN− 1V), 2.3V ≤ VIN≤ 30V, 100µA ≤ IL≤ 100mA, TJ≤ T
JMAX
.
Note 8: The junction-to-ambient thermal resistances are as follows: 180˚C/W and 160˚C/W for the TO-92 package with 0.40 inch and 0.25 inch leads to the printed
circuit board (PCB) respectively, 160˚C/W for the molded plastic SOP (M). The above thermal resistances for the M package apply when the package is soldered
directly to the PCB.
LP4950C-5V and LP4951C
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Electrical Characteristics (Continued)
Note 9: May exceed input supply voltage.
Note 10: When used in dual-supply systems where the output terminal sees loads returned to a negative supply, the output voltage should be diode-clamped to
ground.
Note 11: V
SHUTDOWN
≥ 2V, VIN≤ 30V, V
OUT
= 0, Feedback pin tied to V
TAP
.
Note 12: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 13: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation
effects. Specifications are for a 50 mA load pulse at V
IN
= 30V (1.25W pulse) for T = 10ms.
Note 14: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the specification for thermal regulation.
Note 15: Line regulation for the LP4951C is tested at 150˚C for I
L
= 1 mA. For IL= 100µA and TJ= 125˚C, line regulation is guaranteed by design to 0.2%. See
Typical Performance Characteristics for line regulation versus temperature and load current.
Connection Diagrams
TO-92 Plastic Package (Z) Surface-Mount Package (M)
20052802
Bottom View
20052826
Top View
Ordering Information
Package Output Voltage Temperature
5.0V
TO-92 (Z) LP4950CZ-5.0 −40˚C
<
T
J
<
125˚C
M (M08A) LP4951CM −40˚C
<
T
J
<
125˚C
LP4950C-5V and LP4951C
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Typical Performance Characteristics
Quiescent Current Dropout Characteristics
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20052828
Input Current Input Current
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Output Voltage vs. Temperature of 3
Representative Units Quiescent Current
20052831
20052832
LP4950C-5V and LP4951C
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