SLVS515D December   2004  – November 2015 TLC5940

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 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Test Parameter Equations
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Serial Interface
      2. 8.3.2 Error Information Output
      3. 8.3.3 TEF: Thermal Error Flag
      4. 8.3.4 LOD: LED Open Detection
      5. 8.3.5 Delay Between Outputs
      6. 8.3.6 Output Enable
      7. 8.3.7 Setting Maximum Channel Current
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operating Modes
      2. 8.4.2 Setting DOT Correction
      3. 8.4.3 Setting Grayscale
      4. 8.4.4 Status Information Output
      5. 8.4.5 Grayscale PWM Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Serial Data Transfer Rate
        2. 9.2.2.2 Grayscale (GS) Data
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Power Dissipation Calculation
  12. 12Device and Documentation Support
    1. 12.1 Community Resources
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

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11 Layout

11.1 Layout Guidelines

  1. Place the decoupling capacitor near the VCC pin and GND plane.
  2. Place the current programming resistor Riref close to IREF pin and IREFGND pin.
  3. Route the GND pattern as widely as possible for large GND currents.
  4. Routing wire between the LED cathode side and the device OUTn pin should be as short and straight as possible to reduce wire inductance.
  5. When several ICs are chained, symmetric placements are recommended.

11.2 Layout Example

TLC5940 layout_slvs515.gif Figure 24. Layout Recommendation

11.3 Power Dissipation Calculation

The device power dissipation must be below the power dissipation rating of the device package to ensure correct operation. Equation 10 calculates the power dissipation of device.

Equation 10. TLC5940 q_pd_lvs515.gif

where

  • VCC: device supply voltage
  • ICC: device supply current
  • VOUT: TLC5940 OUTn voltage when driving LED current
  • IMAX: LED current adjusted by R(IREF) Resistor
  • DCn: maximum dot correction value for OUTn
  • N: number of OUTn driving LED at the same time
  • dPWM: duty cycle defined by BLANK pin or GS PWM value