SLDS156B March   2009  – July 2015 TLC59108


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (continued)
  6. Pin Configuration and Functions
  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 Requirements
    7. 7.7 Typical Characteristics
  8. Parameter Measurement Information
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Open-Circuit Detection
      2. 9.3.2 Overtemperature Detection and Shutdown
      3. 9.3.3 Power-On Reset
      4. 9.3.4 External Reset
      5. 9.3.5 Software Reset
      6. 9.3.6 Individual Brightness Control With Group Dimming/Blinking
    4. 9.4 Device Functional Modes
    5. 9.5 Programming
      1. 9.5.1 Characteristics of the I2C Bus
        1. Bit Transfer
        2. Start and Stop Conditions
      2. 9.5.2 System Configuration
      3. 9.5.3 Acknowledge
      4. 9.5.4 Device Address
      5. 9.5.5 Regular I2C Bus Slave Address
      6. 9.5.6 LED All Call I2C Bus Address
      7. 9.5.7 LED Sub Call I2C Bus Address
      8. 9.5.8 Software Reset I2C Bus Address
      9. 9.5.9 Control Register
    6. 9.6 Register Maps
      1. 9.6.1 Register Descriptions
        1.  Mode Register 1 (MODE1)
        2.  Mode Register 2 (MODE2)
        3.  Brightness Control Registers 0 to 7 (PWM0 to PWM7)
        4.  Group Duty Cycle Control Register (GRPPWM)
        5.  Group Frequency Register (GRPFREQ)
        6.  LED Driver Output State Registers (LEDOUT0, LEDOUT1)
        7.  I2C Bus Subaddress Registers 1 to 3 (SUBADR1 to SUBADR3)
        8.  LED All Call I2C Bus Address Register (ALLCALLADR)
        9.  Output Gain Control Register (IREF)
        10. Error Flags Registers (EFLAG)
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Driver Output
        1. Constant Current Output
        2. Adjusting Output Current
      2. 10.1.2 TLC59108 and TLC59108F Differences
    2. 10.2 Typical Application
      1. 10.2.1 Parallel Outputs
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curve
      2. 10.2.2 Multiple Devices
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Examples
  13. 13Device and Documentation Support
    1. 13.1 Community Resources
    2. 13.2 Trademarks
    3. 13.3 Electrostatic Discharge Caution
    4. 13.4 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

10 Application and Implementation


Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

10.1 Application Information

10.1.1 Driver Output Constant Current Output

In LED display applications, TLC59108 provides nearly no current variations from channel to channel and from device to device. While IOUT ≤ 100 mA, the maximum current skew between channels is less than ±3% and less than ±6% between devices. Adjusting Output Current

TLC59108 scales up the reference current (Iref) set by the external resistor (Rext) to sink the output current (Iout) at each output port. The following formulas can be used to calculate the target output current IOUT,target in the saturation region:

Equation 1. VREXT = 1.26 V × VG
Equation 2. Iref = VREXT/Rext, if another end of the external resistor Rext is connected to ground
Equation 3. IOUT,target = Iref × 15 × 3CM – 1

Where Rext is the resistance of the external resistor connected to the REXT terminal, and VREXT is the voltage of REXT, which is controlled by the programmable voltage gain (VG), which is defined by the Configuration Code. The Current Multiplier (CM) determines that the ratio IOUT,target/Iref is 15 or 5. After power on, the default value of VG is 127/128 = 0.992, and the default value of CM is 1, so that the ratio IOUT,target/Iref = 15. Based on the default VG and CM.

Equation 4. VREXT = 1.26 V × 127/128 = 1.25 V
Equation 5. IOUT,target = (1.25 V/Rext) × 15
TLC59108 TLC59108-IOUT-2x2plot.gifFigure 21. IOUT vs VOUT

10.1.2 TLC59108 and TLC59108F Differences

The TLC59108 and TLC59108F are similar devices with the difference being the output structure. The TLC59108 has 8 constant-current outputs while the TLC59108F has 8 open drain outputs. The REXT is used to program the current on the TLC59108 for all channels. The in-line resistors on the OUT pins are used in conjunction with the VLED to set the currents on each TLC59108F channel. Since the resistors are unique for each output, the currents can be set by output by changing the resistor value.

TLC59108 app_1dr_lds156.gifFigure 22. TLC59108 One Driver
TLC59108 app_1dr_lds162.gifFigure 23. TLC59108F One Driver

10.2 Typical Application

10.2.1 Parallel Outputs

The TLC59108 outputs can be wired in parallel to increase the current per LED string.

TLC59108 app_par_lds156.gifFigure 24. Parallel Channels Design Requirements

Set the LED current to 50 mA while the IREF register is at the default value (CG = 0.992). Detailed Design Procedure

The goal of this design is to set the LED current to 50 mA. Because there are two outputs in parallel, the LED current should actually be set to 25 mA. With the IREF register at the default value:

Equation 6. IOUT,target = ( 1.25 V / REXT ) × 15

Using this equation, the appropriate REXT is calculated to be 750 Ω. Application Curve

TLC59108 D001_SLDS156.gifFigure 25. LED Current vs REXTResistor

10.2.2 Multiple Devices

This drawing is an example of using the TLC59108 in a system requiring up to 48 LED strings. The TLC59108 drivers share a single I2C bus. The address pins are set high or low to enable the drivers to be independently accessed (all can be written in parallel through the ALLCALLADR function). The REXT pins are each tied to ground through a programming resistor. Since the devices are independent the resistors on the REXT pins can be of different values allowing multi-color displays.

TLC59108 app_6dr_lds156.gifFigure 26. Six Drivers