L4978 2A Step Down Switching Regulator IC DIP-8

L4978 2A Step Down Switching Regulator IC DIP-8 is a powerful, monolithic integrated circuit designed to operate as a high-efficiency step-down (buck) switching regulator, providing a precise and stable DC output voltage. This device incorporates all the essential active functions, including a 2A switch, oscillator, reference, and protection circuitry, simplifying the design of highly reliable DC/DC converters. The L4978, available in the user-friendly DIP-8 package, can accept a wide range of input voltages. Consequently, it finds extensive use in industrial and automotive applications where high current delivery and thermal efficiency are critical. Therefore, designers frequently select this IC to create compact and efficient power supply solutions for microcontrollers and dedicated load circuits.

Key Features:

• High Output Current: The integrated power switch delivers a guaranteed continuous output current of up to 2 A, supporting medium-power applications.
• Wide Input Voltage Range: The IC accepts input voltages ranging from 5.5 V up to 55 V, making it versatile for 12 V, 24 V, and 48 V battery systems.
• Adjustable Output Voltage: You can easily program the output voltage from 3.7 V to 50 V using an external resistor divider, offering great flexibility.
• High Switching Frequency: Features an internally fixed switching frequency of 100 kHz, which allows for the use of smaller external inductive components.
• Comprehensive Protection: The device includes essential safety features like current limit, thermal shutdown, and saturation protection, guaranteeing robust operation.
• Synchronization Capability: Allows for external synchronization of the switching frequency, thereby controlling noise in sensitive systems.

Technical Specifications:

• Type: Non-Isolated Step-Down Switching Regulator
• Maximum Output Current (I_OUT): 2 A
• Input Voltage Range (V_IN): 5.5 V to 55 V
• Switching Frequency (f_SW): 100 kHz (Fixed)
• Output Voltage Range (V_OUT): 3.7 V to 50 V (Adjustable)
• Reference Voltage (V_REF): 1.27 V ± 2%
• Operating Junction Temperature: −40°C to +150°C

Mechanical Specifications:

• Package Style: DIP-8 (Through-Hole)
• Mounting: Through-Hole Technology (THT)
• Heat Dissipation: The package allows for heat sinking via external PCB copper planes, maximizing thermal performance.
• Lead Material: Tinned Copper Alloy

Dimensions:

• Body Length (DIP-8): ≈ 9.8 mm
• Body Width (DIP-8): ≈ 6.4 mm
• Pin Pitch (Between pins): 2.54 mm (0.1 inch)
• Row Spacing (Between rows): 7.62 mm (0.3 inch)
• Weight: ≈ 0.5 g

Pinout and Wiring:

• Pin 1 (E/A): Error Amplifier Output/Compensation. Connect the compensation network here to stabilize the feedback loop.
• Pin 2 (Feedback): Connect to the center of the output voltage divider network to sense the output voltage.
• Pin 3 (Sync/V_REF): Synchronization Input or Reference Voltage Output (1.27 V). Use this pin to synchronize the IC to an external clock.
• Pin 4 (GND): Ground connection. Crucially, ensure a solid connection for the power ground path.
• Pin 5 (Supply V_S): Input voltage supply (V_IN).
• Pin 6 (Collector): Output switch transistor collector. Connect the catch diode cathode and inductor here.
• Pin 7 (Osc. Output): Oscillator ramp output. Use this pin for external synchronization if needed.
• Pin 8 (Inhibit): Shutdown pin. Pulling this pin low disables the regulator.

Datasheet Reference:

• Download STMicroelectronics L4978 Datasheet

Commonly Used in:

• Industrial Power Supplies: Converting high DC bus voltages (24 V to 48 V) down to standard logic or control voltages.
• Automotive Electronics: Stepping down the vehicle battery voltage (12 V/24 V) for various on-board systems.
• Battery Chargers: As the primary DC/DC stage for efficient charging circuits.
• Distributed Power Systems: Generating local regulated voltages on power distribution boards.

Applications:

• Microcontroller Power Rails: Creating 5 V or 3.3 V rails from unregulated high-voltage inputs.
• High-Efficiency Power Conversion: Replacing bulky and inefficient linear regulators in 2 A load applications.
• Pre-regulator Stages: Providing a stable, intermediate voltage for subsequent low-current linear regulators.
• LED Lighting Drivers: Supplying the constant voltage required for high-power LED arrays.

Equivalent Models:

• LM2576 Series: A comparable line of simple, 3A step-down switching regulators, however, the L4978 often offers a wider V_IN range.
• LT1074: Another classic high-current switching regulator often used for similar buck converter applications.
• MC34063 (High-Current Variants): While more basic, certain high-current implementations of the MC34063 can offer functionality similar to the L4978.

Package Includes:

• 1 x L4978 2A Step Down Switching Regulator IC DIP-8