SLVSEB3A June   2018  – January 2019 TLC6946 , TLC6948

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Schematic of TLC6948 With 48-Multiplexing
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin 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 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Pin Equivalent Input and Output Schematic Diagrams
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Built-In 16Kb Display Memory (SRAM)
      2. 9.3.2  GCLK Dual-Edge Operation
      3. 9.3.3  Programmable Constant-Sink Channel Current
        1. 9.3.3.1 Global Brightness Control (BC)
        2. 9.3.3.2 Select RIREF for a Given BC
      4. 9.3.4  Grayscale (GS) Function (PWM Control)
      5. 9.3.5  Serial Data Interface
      6. 9.3.6  LED-Open Detection (LOD)
      7. 9.3.7  Caterpillar Removal
      8. 9.3.8  Precharge FET
      9. 9.3.9  Thermal Shutdown
      10. 9.3.10 IREF Resistor Short Protection (ISP)
    4. 9.4 Device Functional Modes
      1. 9.4.1 Normal Operating Mode
      2. 9.4.2 Power-Save Mode (PSM)
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedures
        1. 10.2.2.1 Power Supply Voltage
        2. 10.2.2.2 Channel Current and Brightness Control
        3. 10.2.2.3 SCLK and GCLK Frequency
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Examples
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Related Links
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Community Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

9.3.3.2 Select RIREF for a Given BC

The maximum current per channel, IOLCmax, is determined by resistor RIREF, placed between the IREF and GND pins. The voltage on IREF is typically 0.8 V. RIREF can be calculated by Equation 1.

Equation 1. TLC6946 TLC6948 BCEquation.gif

where

  • VIREF is the internal reference voltage on IREF (0.8 V)
  • IOLCmax is the maximum current for each channel
  • Gain is the current gain at BC = 7E (See Table 1)

RIREF must be between 1.02 kΩ and 10.7 kΩ in order to hold the channel sink current IOLC between 25 mA (typical) and 0.3 mA (typical). Otherwise, the output may be unstable.

Table 2. Maximum Constant Current vs External Resistor RIREF

IOLCmax (mA) RIREF (kΩ, typical)
25 1.02
20 1.28
15 1.71
10 2.56
5 5.12
2.4 10.7