NSC LP2957ISX, LP2957IS, LP2957IT Datasheet

LP2957/LP2957A 5V Low-Dropout Regulator for µP Applications
General Description
The LP2957 is a 5V micropower voltage regulator with elec­tronic shutdown, error flag, very low quiescent current (150 µA typical at 1 mA load), and very low dropout voltage (470 mV typical at 250 mA load current).
Output can be wired for snap-on/snap-off operation to elimi­nate transitionvoltage states where µP operation may be un­predictable.
Output crowbar (50 mA typical pull-down current) will bring down the output quickly when the regulator snaps off or when the shutdown function is activated.
The part has tight line and load regulation (0.04%typical) and low output temperature coefficient (20 ppm/˚C typical).
The accuracy of the 5V output is guaranteed at room tem­perature and over the full operating temperature range.
The LP2957 is available in the five-lead TO-220 and TO-263 packages.
Features
n 5V output within 1.4%over temperature (A grade) n Easily programmed for snap-on/snap-off output n Guaranteed 250 mA output current n Extremely low quiescent current n Low Input-Output voltage required for regulation n Reverse battery protection n Extremely tight line and load regulation n Very low temperature coefficient n Current and thermal limiting n Error flag signals when output is out of regulation
Applications
n High-efficiency linear regulator n Battery-powered regulator
Package Outline
Bent, Staggered Leads
5-Lead TO-220 (T)
DS011340-16
Top View
Order Number LP2957AIT or LP2957IT
See NS Package Number T05D
Plastic Surface Mount Package
5-Lead TO-263 (S)
DS011340-17
Top View
DS011340-18
Side View
Order Number LP2957AIS or LP2957IS
See NS Package Number TS5B
June 1998
LP2957/LP2957A 5V Low-Dropout Regulator for µP Applications
© 1999 National Semiconductor Corporation DS011340 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.
Operating Junction
Temperature Range −40˚C to +125˚C
Storage Temperature Range −65˚C to +150˚C
Lead Temperature
(Soldering, 5 Seconds) 260˚C Power Dissipation (Note 2) Internally Limited Input Supply Voltage −20V to +30V Shutdown Input
−0.3V to +30V
ESD Rating 2 kV
Electrical Characteristics
Limits in standard typeface are for T
J
=
25˚C, and limits in boldface type apply over the full operating temperature range. Un-
less otherwise specified: V
IN
=
6V, I
L
=
1 mA, C
L
=
2.2 µF, V
SD
=
3V.
Symbol Parameter Conditions Typical
LP2957AI LP2957I
Units
Min Max Min Max
V
O
Output Voltage 5.0 4.975 5.025 4.950 5.050
V(Note 9) 4.940 5.060 4.900 5.100
1mAI
L
250 mA 5.0 4.930 5.070 4.880 5.120
Output Voltage Temperature Coefficient
(Note 3)
20 100 150 ppm/˚C
Line Regulation V
IN
=
6V to 30V 0.03 0.10 0.20
%
0.20 0.40
Load Regulation I
L
=
1mAto250mA
0.04
0.16 0.20 %
I
L
=
0.1 mA to 1 mA
(Note 4)
0.20 0.30
V
IN–VO
Dropout Voltage I
L
=
1 mA 60 100 100 mV
(Note 5) 150 150
I
L
=
50 mA 240 300 300
420 420
I
L
=
100 mA 310 400 400
520 520
I
L
=
250 mA 470 600 600
800 800
I
GND
Ground Pin Current I
L
=
1 mA 150 200 200 µA
(Note 6) 230 230
I
L
=
50 mA 1.1 2 2 mA
2.5 2.5
I
L
=
100 mA 3 6 6
88
I
L
=
250 mA 16 28 28
33 33
I
GND
Ground Pin Current I
L
=
0 130 180 180 µA
in Shutdown (Note 6) V
SD
=
0.4V 200 200
I
GND
Ground Pin Current V
IN
=
4.5V 180 230 230 µA
at Dropout (Note 6) I
L
=
0.1 mA 250 250
I
O
Off-State Output V
IN
=
5.3V 50 30 30 mA
(Sink) Pulldown Current V
O
=
5V, V
SD
=
0.4V 20 20
I
O
Output Leakage I
(SD IN)
1 µA 3 10 10 µA
(Off) in Shutdown V
IN
=
30V, V
OUT
=
0V 20 20
I
LIMIT
Current Limit R
L
=
1 400 500 500 mA
530 530
Thermal Regulation (Note 7)
0.05 0.2 0.2
%
/W
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Electrical Characteristics (Continued)
Limits in standard typeface are for T
J
=
25˚C, and limits in boldface type apply over the full operating temperature range. Un-
less otherwise specified: V
IN
=
6V, I
L
=
1 mA, C
L
=
2.2 µF, V
SD
=
3V.
Symbol Parameter Conditions Typical
LP2957AI LP2957I
Units
Min Max Min Max
e
n
Output Noise Voltage C
L
=
2.2 µF 500 µV
RMS
(10 Hz to 100 kHz) I
L
=
100 mA
C
L
=
33 µF 320
SHUTDOWN INPUT
VSD(ON) Output Turn-On 1.155 1.305 1.155 1.305 V
Threshold Voltage 1.140 1.320 1.140 1.320 HYST Hysteresis 6 mV I
B
Input Bias V
IN(SD)
=
0V to 5V 10 −30 30 −30 30 nA
Current −50 50 −50 50
DROPOUT DETECTION COMPARATOR
I
OH
Output “HIGH” V
OH
=
30V 0.01 1 1 µA
Leakage 22 V
OL
Output “LOW” V
IN
=
4V 150 250 250 mV
Voltage I
O
(COMP)=400 µA 400 400
V
THR
Upper Threshold (Note 8) −240 −320 −150 −320 −150 mV (Max) Voltage −380 −100 −380 −100 V
THR
Lower Threshold (Note 8) −350 −450 −230 −450 −230 mV (Min) Voltage −640 −160 −640 −160 HYST Hysteresis (Note 8) 60 mV
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the de­vice outside of its rated operating conditions.
Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, T
J
(MAX), the junction-to-ambient thermal resistance, θJA,
and the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient temperature is calculated using:
Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The junction-to-ambient thermal resistance of the TO-220 (without heatsink) is 60˚C/W and 73˚C/W for the TO-263. If the TO-263 package is used, the thermal resistance can be reduced by increasing the P.C. board copper area thermally connected to the package: Using 0.5 Square inches of copper area, θ
JA
is 50˚C/W, with 1 square inch of copper
area, θ
JA
is 37˚C/W; and with 1.6 or more square inches of copper area, θJAis 32˚C/W. The junction-to-case thermal resistance is 3˚C/W. If an external heatsink is used, the effective junction-to-ambient thermal resistance is the sum of the junction-to-case resistance (3˚C/W), the specified thermal resistance of the heatsink se­lected, and the thermal resistance of the interface between the heatsink and the LP2957 (see Application Hints).
Note 3: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note 4: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested separately for load regulation in the load ranges
0.1 mA–1 mA and 1 mA–250 mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. Note 5: Dropout voltage is defined as the input to output voltage differential at which the output voltage drops 100 mV below the value measured with a 1V input
to output differential.
Note 6: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground pin current. Note 7: 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 ef-
fects. Specifications are for a 200 mA load pulse at V
IN
=
20V (3W pulse) for T=10 ms.
Note 8: Voltages are referenced to the nominal regulated output voltage. Note 9: When used in dual-supply systems where the regulator load is returned to a negative supply, the output voltage must be diode-clamped to ground.
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Typical Performance Characteristics Unless otherwise specified: V
IN
=
6V, I
L
=
1 mA, C
L
=
2.2 µF, V
SD
=
3V, T
A
=
25˚C
Ground Pin Current
DS011340-19
Ground Pin Current
DS011340-20
Ground Pin Current vs Load
DS011340-21
Ground Pin Current
DS011340-22
Ground Pin Current
DS011340-23
Output Noise Voltage
DS011340-24
Ripple Rejection
DS011340-25
Ripple Rejection
DS011340-26
Ripple Rejection
DS011340-27
Line Transient Response
DS011340-28
Line Transient Response
DS011340-29
Output Impedance
DS011340-30
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Typical Performance Characteristics Unless otherwise specified: V
IN
=
6V, I
L
=
1 mA, C
L
=
2.2 µF,
V
SD
=
3V, T
A
=
25˚C (Continued)
Load Transient Response
DS011340-31
Load Transient Response
DS011340-32
Dropout Characteristics
DS011340-33
Enable Transient
DS011340-34
Enable Transient
DS011340-35
Short-Circuit Output Current and Maximum Output Current
DS011340-36
Thermal Regulation
DS011340-37
Error Output Sink Current
DS011340-38
Dropout Detection Threshold Voltages
DS011340-39
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