SNVSB12B November   2017  – May 2021 LM73605-Q1 , LM73606-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Characteristics
    7. 7.7 Switching Characteristics
    8. 7.8 System Characteristics
    9. 7.9 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Synchronous Step-Down Regulator
      2. 8.3.2  Auto Mode and FPWM Mode
      3. 8.3.3  Fixed-Frequency Peak Current-Mode Control
      4. 8.3.4  Adjustable Output Voltage
      5. 8.3.5  Enable and UVLO
      6. 8.3.6  Internal LDO, VCC_UVLO, and BIAS Input
      7. 8.3.7  Soft Start and Voltage Tracking
      8. 8.3.8  Adjustable Switching Frequency
      9. 8.3.9  Frequency Synchronization and Mode Setting
      10. 8.3.10 Internal Compensation and CFF
      11. 8.3.11 Bootstrap Capacitor and VBOOT-UVLO
      12. 8.3.12 Power-Good and Overvoltage Protection
      13. 8.3.13 Overcurrent and Short-Circuit Protection
      14. 8.3.14 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Active Mode
        1. 8.4.3.1 CCM Mode
        2. 8.4.3.2 DCM Mode
        3. 8.4.3.3 PFM Mode
        4. 8.4.3.4 Fault Protection Mode
  9. 9 Layout
    1. 9.1 Layout Guidelines
      1. 9.1.1 Layout For EMI Reduction
      2. 9.1.2 Ground Plane
      3. 9.1.3 Optimize Thermal Performance
    2. 9.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Receiving Notification of Documentation Updates
    5. 10.5 Support Resources
    6. 10.6 Support Resources
    7. 10.7 Trademarks
    8. 10.8 Electrostatic Discharge Caution
    9. 10.9 Glossary

Package Options

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

9.2 Typical Application

The LM73605-Q1/6-Q1 only a few external components to perform high-efficiency power conversion, as shown in Figure 9-1.

GUID-0A583D3A-CB44-40B9-921E-780B449FA234-low.gif Figure 9-1 LM73605-Q1/6-Q1 Basic Schematic

The LM73605-Q1/6-Q1 also many practical features to meet a wide range of system design requirements and optimization, such as UVLO, programmable soft-start time, start-up tracking, programmable switching frequency, clock synchronization, and a power-good flag. Note that for ease of use, the feature pins do not require an additional component when not in use. They can be either left floating or shorted to ground. Please refer to the Section 6 for details.

A comprehensive schematic with all features utilized is shown in Figure 9-2.

GUID-AC0A3B4A-FBA3-4411-ADBE-E1FC219B5F75-low.gif Figure 9-2 LM73605-Q1/6-Q1 Comprehensive Schematic with All Features Utilized

The external components must fulfill not only the needs of the power conversion, but also the stability criteria of the control loop. The LM73605-Q1/6-Q1 optimized to work with a range of external components. For quick component selection, Table 9-1 can be used.

Table 9-1 Typical Component Selection
fSW (kHz) VOUT (V) L (µH) COUT (µF)(1) RFBT (kΩ) RFBB (kΩ) RT (kΩ)
350 1 2.2 500 100 OPEN 115
500 1 1.5 400 100 OPEN 78.7 or open
1000 1 0.68 200 100 OPEN 39.2
2200 1 0.47 100 100 OPEN 17.4
350 3.3 4.7 200 100 43.5 115
500 3.3 3.3 150 100 43.5 78.7 or open
1000 3.3 1.8 88 100 43.5 39.2
2200 3.3 1.2 44 100 43.5 17.4
350 5 6.8 120 100 25 115
500 5 4.7 88 100 25 78.7 or open
1000 5 3.3 66 100 25 39.2
2200 5 2.2 44 100 25 17.4
350 12 15 66 100 9.1 115
500 12 10 44 100 9.1 78.7 or open
1000 12 6.8 22 100 9.1 39.2
350 24 22 40 100 4.3 115
500 24 15 30 100 4.3 78.7 or open
(1) All the COUT values are after derating. Add more when using ceramics.