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National Semiconductor
National Semiconductor

LM2937-3.3 Datasheet

400mA and 500mA Voltage Regulators


LM2937-3.3 Datasheet Preview


February 1998
LM2937-2.5, LM2937-3.3
400mA and 500mA Voltage Regulators
General Description
The LM2937-2.5 and LM2937-3.3 are positive voltage regu-
lators capable of supplying up to 500 mA of load current.
Both regulators are ideal for converting a common 5V logic
supply, or higher input 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 qui-
escent current to typically only 10 mA with a full 500 mA load
current when the input to output voltage differential is greater
than 5V.
The LM2937 requires an output bypass capacitor for stabil-
ity. As with most regulators utilizing a PNP pass transistor,
the ESR of this capacitor remains a critical design param-
eter, 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 5. This al-
lows 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 tran-
sients. 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, 0.01up to 5
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
SOT-223 Plastic Package
DS100113-24
Front View
Order Number LM2937ET-2.5, LM2937ET-3.3,
See NS Package Number T03B
DS100113-25
Front View
Order Number LM2937IMP-2.5, LM2937IMP-3.3,
See NS Package Number MA04A
TO-263 Surface-Mount Package
Top View
DS100113-26
Order Number LM2937ES-2.5, LM2937ES-3.3,
See NS Package Number TS3B
DS100113-27
Side View
© 1998 National Semiconductor Corporation DS100113
www.national.com
Page 1

Connection Diagram and Ordering Information (Continued)
Temperature
Range
−40˚C TA 125˚C
−40˚C TA 85˚C
SOT-223 Package
Markings
Output Voltage
2.5 3.3
LM2937ES-2.5
LM2937ET-2.5
LM2937IMP-2.5
L68B
LM2937ES-3.3
LM2937ET-3.3
LM2937IMP-3.3
L69B
NSC
Package
Drawing
TS3B
T03B
MA04A
Package
TO-263
TO-220
SOT-223
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.
www.national.com
2
Page 2

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
Transient (t 100 ms)
Internal Power Dissipation (Note 2)
Maximum Junction Temperature
Storage Temperature Range
Lead Temperature Soldering
TO-220 (10 seconds)
26V
60V
Internally Limited
150˚C
−65˚C to +150˚C
260˚C
TO-263 (10 seconds)
SOT-223 (Vapor Phase, 60 seconds)
SOT-223 (Infrared, 15 seconds)
ESD Susceptibility (Note 3)
230˚C
215˚C
220˚C
2 kV
Operating Conditions(Note 1)
Temperature Range (Note 2)
LM2937ES, LM2937ET
−40˚C TA 125˚C
LM2937IMP
Input Voltage Range
−40˚C TA 85˚C
4.75V to 26V
Electrical Characteristics(Note 4)
V=IN10=µVFNuOnMle+ss5Vot,hIeOrUwTimseaxin=di5c0a0temd.ABfoolrdtfhaeceTOlim-2i2ts0
and TO-263 packages, IOUTmax=400mA for the
apply over the entire operating temperature
SOT-223
range, of
package, COUT
the indicated
device, all other specifications are for TA = TJ = 25˚C.
Output Voltage (VOUT)
Parameter
Conditions
2.5V
Typ Limit
3.3V
Typ Limit
Units
Output Voltage
5 mA IOUT IOUTmax
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)
Load Regulation
Quiescent Current
Output Noise
4.75V VIN 26V,
IOUT = 5 mA
5 mA IOUT IOUTmax
7V VIN 26V,
IOUT = 5 mA
VIN = (VOUT + 5V),
IOUT = IOUTmax
VIN = 5V, IOUT = IOUTmax
10 Hz–100 kHz,
7.5 25 9.9 33 mV(Max)
2.5 25 3.3 33 mV(Max)
2 10 2 10 mA(Max)
10 20 10 20 mA(Max)
66
100125
66
100125
mA(Max)
75 99 µVrms
Voltage
Long Term Stability
IOUT = 5 mA
1000 Hrs.
10 13.2
mV
Short-Circuit Current
Peak Line Transient
Voltage
tf < 100 ms, RL = 100
1.0 0.6 1.0 0.6 A(Min)
75 60 75 60 V(Min)
Maximum Operational
26 26 V(Min)
Input Voltage
Reverse DC
Input Voltage
Reverse Transient
Input Voltage
VOUT −0.6V, RL = 100
tr < 1 ms, RL = 100
−30 −15 −30 −15 V(Min)
−75 −50 −75 −50 V(Min)
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 PMAX = (125 − TA)/θJA, where 125 is the maximum junction temperature for op-
eration, TA is the ambient temperature, and θJA is the junction-to-ambient thermal resistance. If this dissipation is exceeded, the die temperature will rise above 125˚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 θJA 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, θJA is the
sum of the device junction-to-case thermal resistance θJC of 3˚C/W and the heatsink case-to-ambient thermal resistance. If the TO-263 or SOT-223 packages are
used, the thermal resistance can be reduced by increasing the P.C. board copper area thermally connected to the package (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 k.
Note 4: Typicals are at TJ = 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.
3 www.national.com
Page 3
Part Number LM2937-3.3
Manufactur National Semiconductor
Description 400mA and 500mA Voltage Regulators
Total Page 11 Pages
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