L4975 (L4975A) 5A Switching Regulator IC
The L4975 / L4975A is a high-efficiency monolithic step-down (buck) switching regulator IC capable of delivering up to 5A of output current with exceptional performance and reliability. Developed by STMicroelectronics, this regulator integrates an internal power transistor, control circuitry, and full protection features — offering a complete DC-DC converter solution in a single chip.
Operating at a fixed 100 kHz switching frequency, the L4975A provides fast transient response, low ripple, and excellent output voltage regulation. It supports an adjustable output voltage range from 5.1V to 40V, and can operate with input voltages up to 46V, making it a versatile solution for industrial, automotive, and embedded power supply systems.
The L4975A operates using pulse-width modulation (PWM) control to regulate the output voltage by varying the duty cycle of an internal NPN power transistor. The switching action drives an external inductor and diode to step down the input voltage efficiently.
An integrated error amplifier, oscillator, and PWM comparator ensure tight voltage regulation even under varying load conditions. Built-in soft-start, thermal shutdown, and overcurrent protection make the IC robust and dependable in demanding applications.
The remote inhibit function allows the device to be controlled by logic signals, enabling smart power management in microcontroller-based systems.
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Features:-
- 5a Output Current
- 5.1v To 40v Output Voltage Range
- 0 To 90% Duty Cycle Range
- Internal Feed-Forward Line Regulation
- Internal Current Limiting
- Precise 5.1v ± 2% On Chip Reference
- Reset And Power Fail Functions
- Soft Start
- Input/Output Sync Pin
- Under Voltage Lock Out With Hysteretic Turn-On
- Pwm Latch For Single Pulse Per Period
- Very High Efficiency
- Switching Frequency Up To 500khz
- Thermal Shutdown
- Continuous Mode Operation
Specifications:-
| Symbol | Parameters | Values | Units |
| V9 | Input Voltage | 55 | V |
| V9 | Input Operating Voltage | 50 | V |
| V7 | Output DC Voltage | -1 | V |
| Output Peak Voltage at t = 0.1µs f = 200KHz | -7 | ||
| I7 | Maximum Output Current | Internally Limited | |
| V6 | Bootstrap Voltage | 65 | V |
| Bootstrap Operating Voltage | V9 + 15 | ||
| V3, V12 | Input Voltage at Pins 3, 12 | 12 | V |
| V4 | Reset Output Voltage | 50 | V |
| I4 | Reset Output Sink Current | 50 | mA |
| V5, V10, V11, V13 | Input Voltage at Pin 2,7,9,10 | 7 | V |
| I5 | Reset Delay Sink Current | 30 | mA |
| I10 | Error Amplifier Output Sink Current | 1 | A |
| I12 | Soft Start Sink Current | 30 | mA |
| Ptot | Total Power Dissipation at Tcase < 90°C | 30 | W |
| Tj, Tstg | Junction and Storage Temperature | -40 to 150 | °C |
Applications
- Industrial power supplies and automation systems
- Automotive DC-DC converters
- Embedded system power regulation
- Battery chargers and adapters
- Telecommunication and instrumentation equipment
- Microcontroller or digital circuit power sources
*Product image for illustration purposes only, actual product may vary.









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