SLVS569F January   2005  – August 2015 LM2575

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Feedback Connection
      2. 7.3.2 ON/OFF Input
      3. 7.3.3 Fault Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation Mode
      2. 7.4.2 Standby Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Input Capacitor (CIN)
        2. 8.2.2.2  Output Capacitor (COUT)
        3. 8.2.2.3  Catch Diode
        4. 8.2.2.4  Inductor
        5. 8.2.2.5  Output Voltage Ripple and Transients
        6. 8.2.2.6  Feedback Connection
        7. 8.2.2.7  ON/OFF Input
        8. 8.2.2.8  Grounding
        9. 8.2.2.9  Reverse Current Considerations
        10. 8.2.2.10 Buck Regulator Design Procedure
        11. 8.2.2.11 Inductor Selection Guide
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • N|16
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7 Detailed Description

7.1 Overview

The LM2575 provides all the active functions needed for a step-down (buck) switching regulator in an integrated circuit. The wide input-voltage range is 4.75 V to 40 V. The output voltage is programmable by two external resistors. No external frequency compensation is needed. The integrated switch is capable of delivering 1 A of load current, with excellent line and load regulation. The fixed 52-kHz output has cycle-by-cycle current limiting, and thermal shutdown. In addition, a manual shutdown is available through an external ON/OFF pin.

The LM2575 is characterized for operation over the virtual junction temperature range of –40°C to 125°C.

7.2 Functional Block Diagram

LM2575 fbd_lvs569.gif

7.3 Feature Description

7.3.1 Feedback Connection

FEEDBACK must be connected between the two programming resistors. Again, both of these resistors must be in close proximity to the regulator, and each must be less than 100 kΩ to minimize noise pickup.

7.3.2 ON/OFF Input

ON/OFF should be grounded or be a low-level TTL voltage (typically < 1.6 V) for normal operation. To shut down the LM2575 device and place in standby mode, a high-level TTL or CMOS voltage should be supplied to this pin. ON/OFF must not be left open and safely can be pulled up to VIN with or without a pullup resistor.

7.3.3 Fault Protection

In the event of an output short or an overload condition, self-protection features lower the oscillator frequency to approximately 18 kHz and the minimum duty cycle from 5% to approximately 2%. The resulting output voltage drops to approximately 40% of its nominal value, causing the average power dissipated by the IC to lower.

7.4 Device Functional Modes

7.4.1 Normal Operation Mode

When a low-level TTL or CMOS voltage is applied to the ON/OFF pin, the device will provide an output voltage.

7.4.2 Standby Mode

When a high-level TTL or CMOS voltage is applied to the ON/OFF pin, the device enters standby mode, drawing a typical quiescent current of 50 µA. The internal output switch will be turned off.