SLVSCU0 November   2015 TPS92690-Q1

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  Current Regulators
      2. 7.3.2  Peak Current Mode Control
      3. 7.3.3  Switching Frequency and Synchronization
      4. 7.3.4  Current Sense and Current Limit
      5. 7.3.5  Average LED Current
      6. 7.3.6  Precision Reference (VREF)
      7. 7.3.7  Low-Level Analog Dimming
      8. 7.3.8  Soft-Start and Shutdown
      9. 7.3.9  VCC Regulator and Start-Up
      10. 7.3.10 Overvoltage Protection (OVP)
      11. 7.3.11 Input Undervoltage Lockout (UVLO)
      12. 7.3.12 PWM Dimming
      13. 7.3.13 Control Loop Compensation
      14. 7.3.14 Thermal Shutdown
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Inductor
      2. 8.1.2 LED Dynamic Resistance
      3. 8.1.3 Output Capacitor
      4. 8.1.4 Input Capacitor
      5. 8.1.5 MOSFET Selection
      6. 8.1.6 Recirculating Diode
    2. 8.2 Typical Applications
      1. 8.2.1 Basic Topology Schematics
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Operating Point
          2. 8.2.1.2.2  Switching Frequency
          3. 8.2.1.2.3  Average LED Current
          4. 8.2.1.2.4  Inductor Ripple Current
          5. 8.2.1.2.5  Output Capacitance
          6. 8.2.1.2.6  Peak Current Limit
          7. 8.2.1.2.7  Loop Compensation
          8. 8.2.1.2.8  Input Capacitance
          9. 8.2.1.2.9  NFET
          10. 8.2.1.2.10 Diode
          11. 8.2.1.2.11 Input UVLO
          12. 8.2.1.2.12 Output OVLO
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Simplified Application
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1  Operating Point
          2. 8.2.2.2.2  Switching Frequency
          3. 8.2.2.2.3  Average LED Current
          4. 8.2.2.2.4  Inductor Ripple Current
            1. 8.2.2.2.4.1 Minimum Inductor Value
            2. 8.2.2.2.4.2 Inductor Ripple Current
            3. 8.2.2.2.4.3 RMS Inductor Current
          5. 8.2.2.2.5  LED Ripple Current
            1. 8.2.2.2.5.1 Output Capacitor
            2. 8.2.2.2.5.2 Output Capacitor RMS Current
          6. 8.2.2.2.6  Peak Current Limit
          7. 8.2.2.2.7  Loop Compensation
            1. 8.2.2.2.7.1 Compensation Capacitor
            2. 8.2.2.2.7.2 RHP Zero
            3. 8.2.2.2.7.3 Output Capacitor Pole
          8. 8.2.2.2.8  Input Capacitance
          9. 8.2.2.2.9  NFET
            1. 8.2.2.2.9.1 Maximum Average NFET Current
            2. 8.2.2.2.9.2 RMS Transistor Current
          10. 8.2.2.2.10 Diode
            1. 8.2.2.2.10.1 Maximum Average Diode Current
          11. 8.2.2.2.11 Output OVLO
          12. 8.2.2.2.12 Input UVLO
          13. 8.2.2.2.13 Soft-Start
          14. 8.2.2.2.14 PWM Dimming Method
          15. 8.2.2.2.15 Analog Dimming Method
  9. 9 Power Supply Recommendations
    1. 9.1 Bench Supply Current Limit
  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

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

10 Layout

10.1 Layout Guidelines

The performance of any switching regulator depends as much upon the layout of the PCB as the component selection. Following a few simple guidelines maximizes noise rejection and minimizes the generation of EMI within the circuit.

Discontinuous currents are the most likely to generate EMI, therefore care should be taken when routing these paths. In the boost regulator, the discontinuous current flows through the output capacitor (CO), D1, Q1, and RLIM (if used). These loops should be kept as small as possible and the connections between all the components should be short and thick to minimize parasitic inductance. In particular, the switch node (where L1, D1 and Q1 connect) should be just large enough to connect the components. To minimize excessive heating, large copper pours can be placed adjacent to the short current path of the switch node.

The RT, COMP, CSP, IS, IADJ, ILIM, and SYNC pins are all high-impedance inputs which couple external noise easily. Therefore, the loops containing these nodes should be minimized whenever possible.

In some applications the LED or LED array can be far away (several inches or more) from the TPS92690, or on a separate PCB connected by a wiring harness. When an output capacitor is used and the LED array is large or separated from the rest of the regulator, the output capacitor should be placed close to the LEDs to reduce the effects of parasitic inductance on the AC impedance of the capacitor.

10.2 Layout Example

TPS92690-Q1 Layout_slvsbk3.gif Figure 25. Layout Recommendation