NSC LM2937ET-2.5, LM2937ES-2.5, LM2937ESX-2.5, LM2937IMPX-2.5 Datasheet
LM2937-2.5, LM2937-3.3
400mA and 500mA Voltage Regulators
General Description
The LM2937-2.5 and LM2937-3.3 are positive voltage regulators capable of supplying up to 500 mA of load current.
Both regulators are ideal for converting a common 5V logic
supply, orhigherinput supply voltage, to the lower 2.5V and
3.3V supplies to power VLSI ASIC’s and microcontrollers.
Special circuitry has been incorporated to minimize the quiescent current to typically only 10 mA with a full 500 mAload
current when the input to output voltage differential is greater
than 5V.
The LM2937 requires an output bypass capacitor for stability. As with most regulators utilizing a PNP pass transistor,
the ESR of this capacitor remains a critical design parameter, but the LM2937-2.5 and LM2937-3.3 include special
compensation circuitry that relaxes ESR requirements. The
LM2937 is stable for all ESR ratings less than 5Ω. This allows the use of low ESR chip capacitors.
The regulators are also suited for automotive applications,
with built in protection from reverse battery connections,
two-battery jumps and up to +60V/−50V load dump transients. Familiar regulator features such as short circuit and
thermal shutdown protection are also built in.
Features
n Fully specified for operation over −40˚C to +125˚C
n Output current in excess of 500 mA (400mA for
SOT-223 package)
n Output trimmed for 5%tolerance under all operating
conditions
n Wide output capacitor ESR range, 0.01Ω up to 5Ω
n Internal short circuit and thermal overload protection
n Reverse battery protection
n 60V input transient protection
n Mirror image insertion protection
Connection Diagram and Ordering Information
TO-220 Plastic Package
DS100113-24
Front View
Order Number LM2937ET-2.5, LM2937ET-3.3,
See NS Package Number T03B
SOT-223 Plastic Package
DS100113-25
Front View
Order Number LM2937IMP-2.5, LM2937IMP-3.3,
See NS Package Number MA04A
TO-263 Surface-Mount Package
DS100113-26
Top View
DS100113-27
Side View
Order Number LM2937ES-2.5, LM2937ES-3.3,
See NS Package Number TS3B
February 1998
LM2937-2.5, LM2937-3.3 400mA and 500mA Voltage Regulators
© 1998 National Semiconductor Corporation DS100113 www.national.com
Connection Diagram and Ordering Information (Continued)
Temperature
Range
Output Voltage NSC Package
2.5 3.3 Package
Drawing
−40˚C ≤ T
A
≤ 125˚C LM2937ES-2.5 LM2937ES-3.3 TS3B TO-263
LM2937ET-2.5 LM2937ET-3.3 T03B TO-220
−40˚C ≤ T
A
≤ 85˚C LM2937IMP-2.5 LM2937IMP-3.3 MA04A SOT-223
SOT-223 Package
Markings
L68B L69B
The small physical size of the SOT-223 package does not allow sufficient space to provide the complete device part number. The actual devices will be labeled with
the package markings shown.
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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 Voltage
Continuous 26V
Transient (t ≤ 100 ms) 60V
Internal Power Dissipation (Note 2) Internally Limited
Maximum Junction Temperature 150˚C
Storage Temperature Range −65˚C to +150˚C
Lead Temperature Soldering
TO-220 (10 seconds) 260˚C
TO-263 (10 seconds) 230˚C
SOT-223 (Vapor Phase, 60 seconds) 215˚C
SOT-223 (Infrared, 15 seconds) 220˚C
ESD Susceptibility (Note 3) 2 kV
Operating Conditions(Note 1)
Temperature Range (Note 2)
LM2937ES, LM2937ET −40˚C ≤ T
A
≤ 125˚C
LM2937IMP −40˚C ≤ T
A
≤ 85˚C
Input Voltage Range 4.75V to 26V
Electrical Characteristics(Note 4)
V
IN
=
V
NOM
+ 5V, I
OUTmax
=
500 mA for the TO-220 and TO-263 packages, I
OUTmax
=
400mA for the SOT-223 package, C
OUT
=
10 µF unless otherwise indicated. Boldface limits apply over the entire operating temperature range, of the indicated
device, all other specifications are for T
A
=
T
J
=
25˚C.
Output Voltage (V
OUT
) 2.5V 3.3V Units
Parameter Conditions Typ Limit Typ Limit
Output Voltage 5 mA ≤ I
OUT
≤ I
OUTmax
2.42 3.20 V (Min)
2.5 2.38 3.3 3.14 V(Min)
2.56 3.40 V(Max)
2.62 3.46 V(Max)
Line Regulation(Note 5) 4.75V ≤ V
IN
≤ 26V, 7.5 25 9.9 33 mV(Max)
I
OUT
=
5mA
Load Regulation 5 mA ≤ I
OUT
≤ I
OUTmax
2.5 25 3.3 33 mV(Max)
Quiescent Current 7V ≤ V
IN
≤ 26V, 2 10 2 10 mA(Max)
I
OUT
=
5mA
V
IN
=
(V
OUT
+ 5V), 10 20 10 20 mA(Max)
I
OUT
=
I
OUTmax
V
IN
=
5V, I
OUT
=
I
OUTmax
66 100125 66 100125 mA(Max)
Output Noise 10 Hz–100 kHz, 75 99 µVrms
Voltage I
OUT
=
5mA
Long Term Stability 1000 Hrs. 10 13.2 mV
Short-Circuit Current 1.0 0.6 1.0 0.6 A(Min)
Peak Line Transient t
f
<
100 ms, R
L
=
100Ω 75 60 75 60 V(Min)
Voltage
Maximum Operational 26 26 V(Min)
Input Voltage
Reverse DC V
OUT
≥ −0.6V, R
L
=
100Ω −30 −15 −30 −15 V(Min)
Input Voltage
Reverse Transient t
r
<
1 ms, R
L
=
100Ω −75 −50 −75 −50 V(Min)
Input Voltage
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
outside of its rated Operating Conditions.
Note 2: The maximum allowable power dissipation at any ambient temperature is P
MAX
=
(125 − T
A
)/θJA, where 125 is the maximum junction temperature for op-
eration, T
A
is the ambient temperature, and θJAis the junction-to-ambient thermal resistance. If this dissipation isexceeded,thedietemperaturewillriseabove125˚C
and the electrical specifications do not apply. If the die temperature rises above 150˚C, the regulator will go into thermal shutdown. The junction-to-ambient thermal
resistance θ
JA
is 65˚C/W, for the TO-220 package, 73˚C/W for the TO-263 package, and 174˚C/W for the SOT-223 package. When used with a heatsink, θJAis the
sum of the device junction-to-case thermal resistance θ
JC
of 3˚C/W and the heatsink case-to-ambient thermal resistance. If the TO-263 or SOT-223 packages are
used, the thermal resistancecanbereducedbyincreasingtheP.C.boardcopperareathermallyconnectedtothepackage (see Application Hints for more information
on heatsinking).
Note 3: ESD rating is based on the human body model, 100 pF discharged through 1.5 kΩ.
Note 4: Typicals are at T
J
=
25˚C and represent the most likely parametric norm.
Note 5: The minimum input voltage required for proper biasing of these regulators is 4.75V. Below this level the outputs will fall out of regulation. This effect is not
the normal dropout characteristic where the output falls out of regulation due to the PNP pass transistor entering saturation. If a value for worst case effective input
to output dropout voltage is required in a specification, the values should be 2.37V maximum for the LM2937-2.5 and 1.6V maximum for the LM2937-3.3.
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