LM2940 voltage regulator[video+FAQ]: Datasheet, circuit and Equivalent
LM2940 Pinout and Configurations
| Name | NDE | KTT | DCY | NGN | I/O | Description |
| IN | 1 | 1 | 1 | 3 | I | Unregulated input voltage |
| GND | 2 | 2 | 2 | 2 | – | Ground |
| OUT | 3 | 3 | 3 | 5,6 | 0 | Regulated output voltage. |
| GND | 4 | 4 | 4 | 7 | – | Ground |
| N/C | – | – | – | 1,4,8 | – | No connection |
LM2940 Introduction
The LM2940 positive voltage regulator features the ability to source 1A of output current with a dropout voltage of typically 0.5V and a maximum of 1V over the entire temperature range. Furthermore, a quiescent current reduction circuit has been included which reduces the ground current when the differential between the input voltage and the output voltage exceeds approximately 3V.
LM2940: Features
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Dropout Voltage 0.385 V (Typ) at IO = 1A
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Output Current in Excess of 1A
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Output Voltage Trimmed Before Assembly
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Reverse-Battery Protection
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Internal Short-Circuit Current Limit
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Mirror-Image Insertion Protection
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Available in
– Commercial Temperature (0°C to 125°C)
– Extended Temperature (–40°C to 125°C)
LM2940:Applications
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Post Regulator for Switching Supplies
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Logic Power Supplies
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Industrial Instrumentation
LM2940 Equivalent
The equivalent for LM2940 is LM7805.
LM2940 Typical Application
LM2940 Block Diagram
LM2940 Package
LM2940 Manufacturer
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LM2940 Recommended Operating Conditions
LM2940 vs LM7805
The LM7805 is a popular linear voltage regulator because it requires no additional components to operate. It is a very low-cost component.
Because of its characteristics, it reduces the output voltage at the expense of heat dissipation, making it inefficient.
The LM7805 requires a minimum input voltage of 7.3V to function properly. It can handle a maximum current of 1A. Some models can handle up to 1.5A.
It is recommended, and in some cases required, to use capacitors to reduce or eliminate the effects of the frequencies introduced by the other elements of the circuit. They also help to reduce the impact of peak consumption.
While the LM2940 is from a different generation, its pin is still compatible with the LM7805,
It is a Low-dropout (LDO) Linear Regulator that is more efficient than the LM7805. but it will require capacitors.
The main difference between LM2940 and LM7805 is that the maximum output current of LM2940 is 1A. The maximum output current of LM7805 is 1.5A. Others are very close, so if the circuit only requires 1A or below, LM2940 can be used instead of LM7805
What’s more, the 7805 is expending the excess power as heat. This is very lossy especially if your project uses batteries. The other chip is a buck converter so it approaches 90% efficiency by switching so there is no waste heat, that’s why even though LM7805 is cheaper and easier to use but there are still a lot of people who would go for LM2940.
LM2940 & LM7805 Schematic Comparison
LM2940 Schematic LM7805 Schematic
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