LM2586T ADJ
LM2586T ADJ - Adjustable Switching Regulator
Overview
The LM2586T ADJ is a monolithic integrated circuit from the LM2586 series, specifically engineered for high-efficiency switching regulator applications. This adjustable version provides designers with flexibility in setting the output voltage to meet specific system requirements. The device is optimized for flyback, step-up (boost), and forward converter topologies, making it suitable for a wide range of power supply designs.
With its integrated architecture, the LM2586T ADJ simplifies power supply design while delivering robust performance. The regulator operates at a fixed frequency of 150 kHz, which provides a good balance between efficiency and component size. The current-mode control architecture ensures excellent line and load regulation characteristics.
Features
- Adjustable output voltage from 1.23V to 60V
- 150 kHz fixed frequency internal oscillator
- Current-mode control architecture
- Integrated soft-start function (typically 10 ms)
- Cycle-by-cycle current limiting
- External shutdown capability
- ±4% output voltage tolerance
- Wide input voltage range: 4V to 40V
- Up to 3A output switch current
- Thermal shutdown protection
- Available in TO-220-5 package
Applications
The LM2586T ADJ is versatile enough for numerous power conversion applications:
- DC-DC boost converters
- Flyback converters
- Forward converters
- Industrial power supplies
- Automotive power systems
- Telecommunications equipment
- Battery charging circuits
- LED driver circuits
- Distributed power systems
Electrical Characteristics
Absolute Maximum Ratings
- Input Voltage: -0.3V to +45V
- Output Switch Voltage: -0.3V to +65V
- Shutdown Pin Voltage: -0.3V to +25V
- Feedback Pin Voltage: -0.3V to +25V
- Operating Junction Temperature: +150°C
- Storage Temperature Range: -65°C to +150°C
Recommended Operating Conditions
- Input Voltage Range: 4V to 40V
- Output Voltage Range: 1.23V to 60V
- Operating Temperature Range: -40°C to +125°C
- Maximum Output Current: 3A (dependent on thermal conditions)
Typical Performance Characteristics
- Switching Frequency: 150 kHz ±10%
- Feedback Voltage: 1.23V ±2%
- Quiescent Current: 11 mA typical
- Shutdown Current: 50 µA typical
- Soft-start Time: 10 ms typical
- Current Limit Threshold: 3.3A typical
- Thermal Shutdown Threshold: 165°C typical
Package Information
TO-220-5 Package Details
The LM2586T ADJ is available in a 5-pin TO-220 package with the following pin configuration:
- Pin 1: Feedback (FB) - Connects to the voltage divider network for output voltage regulation
- Pin 2: Shutdown (SD) - Active high shutdown control (internal pull-down)
- Pin 3: Input (VIN) - Power supply input
- Pin 4: Ground (GND) - Circuit ground
- Pin 5: Output (SW) - Switch output to inductor
Mechanical Specifications
- Package Type: Through-hole mounted
- Number of Pins: 5
- Lead Material: Copper alloy
- Lead Finish: Matte Tin
- Package Dimensions: 10.16mm x 8.89mm x 4.45mm (LxWxH)
- Mounting Style: Vertical or horizontal
- Thermal Resistance (Junction-to-Ambient): 35°C/W
- Thermal Resistance (Junction-to-Case): 3°C/W
Design Considerations
Output Voltage Setting
The output voltage is set using an external resistor divider network connected between the output and the FB pin. The relationship is given by:
VOUT = 1.23V × (1 + R1/R2)
Where R1 is the resistor from output to FB pin, and R2 is the resistor from FB pin to ground.
Inductor Selection
For optimal performance, select an inductor with:
- Current rating exceeding the maximum output current
- Low DC resistance to minimize power loss
- Saturation current at least 30% higher than peak switch current
- Recommended inductance range: 33 µH to 220 µH for most applications
Thermal Management
Proper heat sinking is essential when operating at high currents or high ambient temperatures:
- Use a thermal pad or heatsink for continuous operation above 1A
- Ensure adequate airflow in enclosed designs
- Monitor junction temperature to prevent thermal shutdown
Typical Application Circuit
A basic step-up (boost) converter configuration includes:
- Input capacitor (10 µF to 100 µF ceramic or electrolytic)
- Output capacitor (47 µF to 470 µF low-ESR type)
- Schottky diode (3A, 60V minimum)
- Inductor (selected per design requirements)
- Feedback resistor divider network
- Optional input filter for noise-sensitive applications
