SBVS225B March   2013  – May 2014 TLC5973

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 Handling 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 Pin-Equivalent Input and Output Schematic Diagrams
    2. 7.2 Test Circuits
    3. 7.3 Timing Diagrams
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Grayscale (GS) Control
      2. 8.3.2 EasySet and Shunt Regulator
      3. 8.3.3 No Limit Cascading
      4. 8.3.4 Constant Sink Current Value
      5. 8.3.5 Connector Design
    4. 8.4 Device Functional Modes
      1. 8.4.1 Grayscale (GS) Function (PWM Control)
        1. 8.4.1.1 PWM Control
      2. 8.4.2 One-Wire Interface (EasySet) Data Writing Method
        1. 8.4.2.1 Data Transfer Rate (tCYCLE) Measurement Sequence
        2. 8.4.2.2 Data ‘0’ and Data ‘1’ Write Sequence (Data Write Sequence)
        3. 8.4.2.3 One Communication Cycle End of Sequence (EOS)
        4. 8.4.2.4 GS Data Latch (GSLAT) Sequence
    5. 8.5 Programming
      1. 8.5.1 Controlling Devices Connected in Series
    6. 8.6 Register Maps
      1. 8.6.1 Register and Data Latch Configuration
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 No Internal Shunt Regulator Mode 1
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curve
      2. 9.2.2 No Internal Shunt Regulator Mode 2
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curve
      3. 9.2.3 Internal Shunt Regulator Mode
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Trademarks
    2. 12.2 Electrostatic Discharge Caution
    3. 12.3 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9 Applications and Implementation

9.1 Application Information

The device is a constant sink current LED driver. This device is typically used to minimize wiring cost in applications and also provides no restrictions of cascading multiple devices in series. Furthermore, the device maximum data transfer rate is 3 Mbps and can contribute high-frequency display data change rates. The following design procedures can be used to maximize application design with minimal wiring cost. The device is also a good choice for higher VCC power-supply voltage applications because of the internal shunt regulator included in the device.

9.2 Typical Applications

9.2.1 No Internal Shunt Regulator Mode 1

This application does not use the shunt regulator. However, the device VCC and LED lamp anode voltage can be supplied from the same power supply because only one LED lamp is connected in series.

TLC5973 typ_app1_bvs225.gif Figure 22. No Internal Shunt Regulator Mode 1 Typical Application Circuit

9.2.1.1 Design Requirements

Table 4. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Input voltage range for VCC 3.0 V or LED forward voltage (VF) + 1 V to 5.5 V
SDI voltage range Low level = GND, high level = VCC
SDI data transfer rate 100 kbps to 3 Mbps

9.2.1.2 Detailed Design Procedure

The OUTn (n = 0 to 2) constant output current is set by an external resistor connected between the device IREF and GND pins. Use Equation 1 to calculate the requirements for RIREF.

9.2.1.3 Application Curve

One LED is connected to each output.

TLC5973 Scope_01_SBVS225.gif
VCC = 5 V RIREF = 2.7 kΩ SDI high = 5 V
GS data = 7FFh (50% on duty)
Figure 23. No Internal Shunt Regulator Mode 1 Waveform

9.2.2 No Internal Shunt Regulator Mode 2

This application does not use the shunt regulator. However, the device VCC and LED lamp anode voltage are supplied from different power supplies.

TLC5973 typ_app2_bvs225.gif Figure 24. No Internal Shunt Regulator Mode 2 Typical Application Circuit

9.2.2.1 Design Requirements

Table 5. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Input voltage range for VCC 3.0 V to 5.5 V
Input voltage range for LED lamp LED forward voltage (VF) × the number of LED lamps + 1 V; maximum voltage is 24 V
SDI voltage range Low level = GND, high level = VCC
SDI data frequency 100 kbps to 3 Mbps

9.2.2.2 Detailed Design Procedure

The OUTn (n = 0 to 2) constant output current is set by an external resistor connected between the device IREF and GND pins. Use Equation 1 to calculate the requirements for RIREF.

9.2.2.3 Application Curve

Six LEDs are connected in series to each output.

TLC5973 Scope_02_SBVS225.gif
VCC = 3.3 V VLED = 21 V RIREF = 2.7 kΩ
SDI high = 3.3 V GS data = 7FFh (50% on duty)
Figure 25. No Internal Shunt Regulator Mode 2 Waveform

9.2.3 Internal Shunt Regulator Mode

This application uses the shunt regulator. The device VCC and LED lamp anode voltage are supplied from the same power supply. At least two LED lamps are connected in series.

TLC5973 typ_app3_bvs225.gif Figure 26. Internal Shunt Regulator Mode Typical Application Circuit

9.2.3.1 Design Requirements

Table 6. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Input voltage range for VLED 6 V to 24 V
SDI voltage range Low level = GND, high level = 5.0 V to 6.0 V
SDI data transfer rate 100 kbps to 3 Mbps

9.2.3.2 Detailed Design Procedure

The TLC5973 internally integrates a shunt regulator to regulate VCC voltage. Refer to Figure 27 for an application circuit that uses the internal shunt regulator through a resistor, RVCC. The recommended RVCC value can be calculated by Equation 2.

Equation 2. TLC5973 q_rvcc_bvs225.gif
TLC5973 ai_app_cir_int_shunt_mode_bvs225.gif Figure 27. Internal Shunt Regulator Mode Application Circuit

Table 7 shows the typical resistor value for several VLED voltages. Note that the CVCC value should be 0.1 μF.

Table 7. Resistor Example for Shunt Resistor versus LED Voltage(1)

VLED (V) RVCC (Ω) RESISTOR WATTAGE (W)
9 270 0.04
12 510 0.07
18 1000 0.15
24 1500 0.22
(1) RIREF is at 1.5 kΩ.

9.2.3.3 Application Curves

Six LEDs are connected in series to each output.

TLC5973 Scope_03_SBVS225.gif
VLED = 21 V RIREF = 2.7 kΩ RVCC = 1.2 kΩ
SDI high = 6 V GS data = 7FFh (50% on duty)
Figure 28. Internal Shunt Regulator Mode Waveform 1
TLC5973 Scope_04_SBVS225.gif
VLED = 21 V RIREF = 2.7 kΩ RVCC = 1.2 kΩ
SDI high = 6 V GS data = 7FFh (50% on duty)
Figure 29. Internal Shunt Regulator Mode Waveform 2