Overview
The LM2940SX-12/NOPB, produced by Texas Instruments, is a 1-A low dropout voltage regulator. This device is designed to source 1 A of output current with a dropout voltage of typically 0.5 V and a maximum of 1 V over the entire temperature range. It features a quiescent current reduction circuit, which minimizes ground current when the input-output voltage differential exceeds approximately 3 V. This regulator is well-suited for applications requiring high current output and robust protection features, including short-circuit current limit, overvoltage shutdown, and thermal shutdown.
Key Specifications
| Parameter | Test Conditions | Unit | Typical | Minimum | Maximum |
|---|---|---|---|---|---|
| Output Current | - | A | - | - | 1 |
| Dropout Voltage | IOUT = 1 A | V | 0.5 | - | 1 |
| Input Voltage Range | VOUT + 1 V to 26 V | V | - | VOUT + 1 | 26 |
| Output Voltage (12 V Version) | 5 mA ≤ IOUT ≤ 1 A, TJ = 25°C | V | 12 | 11.64 | 12.36 |
| Line Regulation | 50 mA ≤ IOUT ≤ 1 A, TJ = 25°C | mV | 60 | 20 | 120 |
| Load Regulation | 50 mA ≤ IOUT ≤ 1 A, TJ = 25°C | mV | 60 | 20 | 150 |
| Quiescent Current | VIN = VOUT + 5 V, IOUT = 1 A | mA | 30 | 10 | 60 |
| Output Noise Voltage | 10 Hz to 100 kHz, IOUT = 5 mA | µVrms | 360 | 270 | 450 |
| Ripple Rejection | ƒOUT = 120 Hz, 1 Vrms, IOUT = 100 mA | dB | 54 | 48 | 66 |
Key Features
- High Output Current: Capable of sourcing 1 A of output current.
- Low Dropout Voltage: Typically 0.5 V and a maximum of 1 V over the entire temperature range.
- Quiescent Current Reduction: Reduces ground current when the input-output voltage differential exceeds approximately 3 V.
- Short-Circuit Current Limit: Protects against high-load current faults or shorting events.
- Overvoltage Shutdown (OVSD): Disables the output if the input voltage exceeds typically 30 V.
- Thermal Shutdown (TSD): Protects the device from overheating.
- Mirror Image Insertion Protection: Protected from reverse battery installations or two-battery jumps.
- Line and Load Regulation: Ensures stable output voltage under varying input and load conditions.
Applications
- Vehicular Applications: Designed to withstand the harsh conditions of automotive environments, including reverse battery installations and load dump transients.
- Post Regulator for Switching Supplies: Used to regulate the output of switching power supplies to provide a stable and low-noise voltage.
- Logic Power Supplies: Suitable for powering logic circuits that require a stable and regulated voltage.
- Industrial Instrumentation: Used in various industrial applications where high reliability and stability are crucial.
Q & A
- What is the maximum output current of the LM2940SX-12/NOPB?
The maximum output current is 1 A.
- What is the typical dropout voltage of the LM2940SX-12/NOPB?
The typical dropout voltage is 0.5 V.
- What is the input voltage range for the LM2940SX-12/NOPB?
The input voltage range is from VOUT + 1 V to 26 V.
- Does the LM2940SX-12/NOPB have overvoltage protection?
Yes, it has an overvoltage shutdown feature that disables the output if the input voltage exceeds typically 30 V.
- Is the LM2940SX-12/NOPB protected against short-circuit conditions?
Yes, it has an internal current limit circuit to protect against high-load current faults or shorting events.
- What is the quiescent current of the LM2940SX-12/NOPB when the input-output differential is 5 V?
The quiescent current is typically 30 mA when the input-output differential is 5 V.
- Does the LM2940SX-12/NOPB have thermal shutdown protection?
Yes, it has thermal shutdown protection to prevent overheating.
- What are the common applications of the LM2940SX-12/NOPB?
Common applications include vehicular systems, post regulators for switching supplies, logic power supplies, and industrial instrumentation.
- How should the LM2940SX-12/NOPB be laid out on a PCB for optimal performance?
For optimal performance, place CIN and COUT on the same side of the PCB as the LM2940 and as close as possible to the package. Ensure ground connections for CIN and COUT are back to the LM2940 ground pin.
- What is the ripple rejection of the LM2940SX-12/NOPB?
The ripple rejection is typically 54 dB at ƒOUT = 120 Hz, 1 Vrms, and IOUT = 100 mA.
