SLVS765B October   2008  – September 2015 TLC5925

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: VDD = 3 V
    6. 6.6  Electrical Characteristics: VDD = 5.5 V
    7. 6.7  Power Dissipation and Thermal Impedance
    8. 6.8  Timing Requirements
    9. 6.9  Switching Characteristics: VDD = 3 V
    10. 6.10 Switching Characteristics: VDD = 5.5 V
    11. 6.11 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Constant Current
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Turning on the LEDs
      2. 9.1.2 Propagation Delay Times
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Adjusting Output Current
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  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

Package Options

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

9 Application and Implementation

NOTE

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.

9.1 Application Information

9.1.1 Turning on the LEDs

To turn on an LED connected to one of the outputs of the device, the output must be pulled low. To do this, the SDI signal must let the device know which outputs should be activated. Using the rising edge of CLK, the logic level of the SDI signal latches the desired state of each output into the shift register. Once this is complete, the LE signal must be toggled from low to high then back to low. Once /OE is pulled down, the corresponding outputs will be pulled low and the LEDs will be turned on. The below diagram shows outputs 0, 3, 4, 5, 10, 13, and 15 being activated.

TLC5925 t_normal_mode_lvs765.gif Figure 6. Timing Diagram

9.1.2 Propagation Delay Times

TLC5925 clk_to_out7_lvs765.gif Figure 7. CLK to OUT7
TLC5925 oe_to_out7_lvs765.gif Figure 9. OE to OUT7
TLC5925 oe_to_out1_lvs765.gif Figure 8. OE to OUT1

9.2 Typical Application

TLC5925 TLC5925_Typical.jpg

9.2.1 Design Requirements

For the following design procedure, the input voltage (VDD) is between 3 V and 5.5 V.

9.2.2 Detailed Design Procedure

9.2.2.1 Adjusting Output Current

TLC5925 sets IOUT based on the external resistor Rext. Users can follow the below formulas to calculate the target output current IOUT,target in the saturation region:

IOUT,target = (1.21 V / Rext) × 18, where Rext is the external resistance connected between R-EXT and GND.

Therefore, the default current is approximately 26 mA at 840 Ω and 13 mA at 1680 Ω.

9.2.3 Application Curve

The default relationship after power on between IOUT,target and Rext is shown in Figure 10.

TLC5925 g_iout_rext_lvs765.gif Figure 10. Default Relationship Curve Between IOUT,target and Rext After Power Up