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 regulators 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 quiescent 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 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
nFully specified for operation over −40ÊC to +125ÊC
nOutput current in excess of 500 mA (400mA for SOT-223 package)
nOutput trimmed for 5% tolerance under all operating conditions
nWide output capacitor ESR range, 0.01Ω up to 5Ω
nInternal short circuit and thermal overload protection
nReverse battery protection
n60V input transient protection
nMirror image insertion protection
Connection Diagram and Ordering Information
TO-220 Plastic Package |
SOT-223 Plastic Package |
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DS100113-24 |
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Front View |
DS100113-25 |
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Front View |
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Order Number LM2937ET-2.5, LM2937ET-3.3, |
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Order Number LM2937IMP-2.5, LM2937IMP-3.3, |
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See NS Package Number T03B |
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See NS Package Number MA04A |
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TO-263 Surface-Mount Package |
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DS100113-27 |
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Side View |
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DS100113-26
Top View
Order Number LM2937ES-2.5, LM2937ES-3.3,
See NS Package Number TS3B
Regulators Voltage 500mA and 400mA 3.3-LM2937 5,.2-LM2937
© 1998 National Semiconductor Corporation |
DS100113 |
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Connection Diagram and Ordering Information (Continued)
Temperature |
Output Voltage |
NSC |
Package |
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Range |
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2.5 |
3.3 |
Package |
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Drawing |
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−40ÊC |
≤ TA ≤ 125ÊC |
LM2937ES-2.5 |
LM2937ES-3.3 |
TS3B |
TO-263 |
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LM2937ET-2.5 |
LM2937ET-3.3 |
T03B |
TO-220 |
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−40ÊC |
≤ TA ≤ 85ÊC |
LM2937IMP-2.5 |
LM2937IMP-3.3 |
MA04A |
SOT-223 |
SOT-223 Package |
L68B |
L69B |
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Markings |
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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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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 |
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Continuous |
26V |
Transient (t £ 100 ms) |
60V |
Internal Power Dissipation (Note 2) |
Internally Limited |
Maximum Junction Temperature |
150ÊC |
Storage Temperature Range |
−65ÊC to +150ÊC |
Lead Temperature Soldering |
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TO-220 (10 seconds) |
260ÊC |
TO-263 (10 seconds) |
230ÊC |
SOT-223 (Vapor Phase, 60 seconds) |
215ÊC |
SOT-223 (Infrared, 15 seconds) |
220ÊC |
ESD Susceptibility (Note 3) |
2 kV |
Operating Conditions(Note 1)
Temperature Range (Note 2) |
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LM2937ES, LM2937ET |
−40ÊC |
£ TA £ 125ÊC |
LM2937IMP |
−40ÊC |
£ TA £ 85ÊC |
Input Voltage Range |
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4.75V to 26V |
Electrical Characteristics(Note 4)
VIN = VNOM + 5V, IOUTmax = 500 mA for the TO-220 and TO-263 packages, IOUTmax=400mA for the SOT-223 package, COUT
= 10 µF unless otherwise indicated. Boldface limits apply over the entire operating temperature range, of the indicated device, all other specifications are for TA = TJ = 25ÊC.
Output Voltage (VOUT) |
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2.5V |
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3.3V |
Units |
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Parameter |
Conditions |
Typ |
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Limit |
Typ |
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Limit |
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Output Voltage |
5 mA £ IOUT £ IOUTmax |
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2.42 |
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3.20 |
V (Min) |
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2.5 |
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2.38 |
3.3 |
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3.14 |
V(Min) |
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2.56 |
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3.40 |
V(Max) |
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2.62 |
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3.46 |
V(Max) |
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Line Regulation(Note 5) |
4.75V £ VIN £ 26V, |
7.5 |
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25 |
9.9 |
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33 |
mV(Max) |
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IOUT = 5 mA |
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Load Regulation |
5 mA £ IOUT £ IOUTmax |
2.5 |
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25 |
3.3 |
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33 |
mV(Max) |
Quiescent Current |
7V £ VIN £ 26V, |
2 |
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10 |
2 |
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10 |
mA(Max) |
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IOUT = 5 mA |
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VIN = (VOUT + 5V), |
10 |
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20 |
10 |
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20 |
mA(Max) |
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IOUT = IOUTmax |
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VIN = 5V, IOUT = IOUTmax |
66 |
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100125 |
66 |
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100125 |
mA(Max) |
Output Noise |
10 Hz±100 kHz, |
75 |
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99 |
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µVrms |
Voltage |
IOUT = 5 mA |
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Long Term Stability |
1000 Hrs. |
10 |
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13.2 |
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mV |
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Short-Circuit Current |
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1.0 |
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0.6 |
1.0 |
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0.6 |
A(Min) |
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Peak Line Transient |
tf < 100 ms, RL = 100W |
75 |
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60 |
75 |
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60 |
V(Min) |
Voltage |
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Maximum Operational |
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26 |
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26 |
V(Min) |
Input Voltage |
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Reverse DC |
VOUT ³ −0.6V, R L = 100W |
−30 |
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−15 |
−30 |
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−15 |
V(Min) |
Input Voltage |
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Reverse Transient |
tr < 1 ms, RL = 100W |
−75 |
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−50 |
−75 |
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−50 |
V(Min) |
Input Voltage |
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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 − T A)/θJA, where 125 is the maximum junction temperature for operation, 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 125ÊC and the electrical specifications do not apply. If the die temperature rises above 150ÊC, the regulator will go into thermal shutdown. The junction-to-ambient thermal resistance θJA is 65ÊC/W, for the TO-220 package, 73ÊC/W for the TO-263 package, and 174ÊC/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 3ÊC/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 kΩ.
Note 4: Typicals are at TJ = 25ÊC 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 |
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