LM2940S-5.0 Basics
The LM2940S-5.0 is a positive voltage regulator capable of delivering up to 1 A of output current, with a typical dropout voltage of 0.5 V and a maximum of 1 V across the entire temperature range. It features a quiescent current reduction circuit that minimizes ground current when the voltage difference between the input and output exceeds about 3 V. As a result, with 1 A of output current and a 5 V differential, the quiescent current is only 30 mA. Higher quiescent currents occur only when the regulator is in dropout mode, where the input-output voltage difference is less than or equal to 3 V.
LM2940S-5.0 Pin Configuration
IN: Input voltage pin. Connect this to the input voltage source (greater than 5V).
GND: Ground pin. This should be connected to the system ground.
OUT: Output voltage pin. This provides the regulated output of 5.0V.
GND: Another ground pin. Often there are multiple ground pins to facilitate easier connections.
N/C (No Connect): This pin is not connected and can be left unconnected.
LM2940S-5.0 Symbol
LM2940S-5.0 Footprint
LM2940S-5.0 3D Model
LM2940S-5.0 Functional Block Diagram
LM2940S-5.0 Specification
| Specification | Value |
| Output Voltage (Max) | 26 V |
| Output Voltage (Min) | 5V |
| Output Current | 1 A |
| Voltage Dropout (Max) | 1V @ 1A |
| Quiescent Current | 10 mA |
| Supply Current (Max) | 15 mA |
| Temperature Range | -40°C ~ 125°C |
| Package Type | TO-263-4, D2PAK (3 Leads + Tab), TO-263AA |
| Input Voltage Range | Up to 26 V |
| PSRR | 64dB (120Hz) |
LM2940S-5.0 Typical Application Circuit
The LM2940S voltage regulators feature the ability to source 1 A of output current with adropout voltage of typically 0.5 V and a maximum of 1 V over the entire temperature range. The output capacitor, COUT, must have a capacitance value of at least 22 µF with an ESR of at least 100 mΩ, but no more than 1 Ω.
The minimum capacitance value and the ESR requirements apply across the entire expected operating ambient temperature range.
LM2940S-5.0 Features
Input Voltage Range = 6 V to 26 V
Dropout Voltage Typically 0.5 V at IOUT = 1 A
Output Current in Excess of 1 A
Output Voltage Trimmed Before Assembly
Reverse Battery Protection
Internal Short Circuit Current Limit
Mirror Image Insertion Protection
P + Product Enhancement Tested
LM2940S-5.0 Applications
Post Regulator for Switching Supplies
Logic Power Supplies
Industrial Instrumentation
How to Use LM2940S-5.0?
First, gather the LM2940S-5.0 chip, the required power supply, output capacitor, input capacitor, and necessary connecting wires.
Next, connect the positive terminal of the power supply to the input pin (IN) of the LM2940S-5.0, and the negative terminal to pin (GND). Connect a 0.1μF capacitor between the input pin and ground. Then, connect the output pin (OUT) of the LM2940S-5.0 to the load you need to power, while also connecting a 22μF capacitor between the output pin and ground to ensure stable output. Note: The GND pin must be connected to the circuit's common ground.
Once everything is connected, power the circuit and use a multimeter to measure the output voltage, ensuring it is stable at 5V.
FAQs
What is the LM2940S-5.0 used for?
The LM2940S-5.0 is a positive voltage regulator designed to provide a stable output voltage of 5V. It is commonly used in power supply circuits for various electronic devices.
How do I connect the LM2940S-5.0 in a circuit?
To connect the LM2940S-5.0, connect the input pin (IN) to the power supply's positive terminal, the ground pin (GND) to the circuit ground, and the output pin (OUT) to the load.
What capacitors should I use with the LM2940S-5.0?
It is recommended to use a 0.1μF capacitor at the input and a 22μF capacitor at the output to ensure stable operation.
