SBVS241 April   2014 TLC5954

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 Output Current Calculation
      2. 8.3.2 Status Information Data (SID)
      3. 8.3.3 LED Open Detection (LOD)
      4. 8.3.4 LED Short Detection (LSD)
      5. 8.3.5 Noise Reduction
    4. 8.4 Device Functional Modes
      1. 8.4.1 Maximum Constant Sink Current
      2. 8.4.2 Global Brightness Control (BC) Function: Sink Current Control
      3. 8.4.3 Constant-Current Output On or Off Control
      4. 8.4.4 Power-Save Mode
    5. 8.5 Register Maps
      1. 8.5.1 Register and Data Latch Configuration
        1. 8.5.1.1 Common Shift Register
        2. 8.5.1.2 Output On or Off Data Latch
        3. 8.5.1.3 Maximum Current Control (MC), Global Brightness Control (BC), and Function Control (FC) Data Latch
  9. 9 Applications 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 Step-by-Step Design Procedure
        2. 9.2.2.2 Maximum Current (MC) Data
        3. 9.2.2.3 Global Brightness Control (BC) Data
        4. 9.2.2.4 On or Off Data
        5. 9.2.2.5 Other Control Data
        6. 9.2.2.6 Grayscale Control
      3. 9.2.3 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 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

9 Applications and Implementation

9.1 Application Information

The device is a 48-channel, constant sink current, LED driver. This device is typically connected in series to drive many LED lamps with only a few controller ports. Output current control data and on or off control data can be written from the SIN input pin. The on or off timing can be controlled by the BLANK signal. Also, the LED open and short error flag can be read out from the SOUT output pin.

9.2 Typical Application

In this application, the device VCC and LED lamp anode voltages are supplied from different power supplies.

ai_typ_app_sbvs241.gifFigure 37. Typical Application Circuit (Multiple Daisy-Chained Devices)

9.2.1 Design Requirements

For this design example, use the following as the input parameters.

Table 11. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
VCC input voltage range 3.0 V to 3.6 V
LED lamp (VLED) input voltage range Maximum LED forward voltage (VF) + 0.4 V (knee voltage)
SIN, SCLK, LAT, and BLANK voltage range Low level = GND, high level = VCC

9.2.2 Detailed Design Procedure

9.2.2.1 Step-by-Step Design Procedure

To begin the design process, a few parameters must be decided upon. The designer needs to know the following:

  • Maximum output constant-current value for all colors of the LED ramp.
  • Maximum LED forward voltage (VF).
  • Current ratio of red, green, and blue LED lamps for the best white balance.
  • Is the LED open detect (LOD) function used? If so, which detection level (0.20 V, 0.30 V, 0.40 V, 0.50 V, or 0.60 V) is used?
  • Is the LED short detect (LSD) function used? If so, which detection level (50% VCC, 70% VCC, or 90% VCC) is used?

9.2.2.2 Maximum Current (MC) Data

There are a total of three bits of MC data that set the output current of all constant-current outputs (OUTXn). Select the MC data to be greater than the target LED ramp current if the output current is reduced white balanced by the global brightness control data and write the data with other control data.

9.2.2.3 Global Brightness Control (BC) Data

There are a total of three sets of 7-bit BC data for the red, green, and blue LED ramp. Select the BC data for the best white balance of the red, green, and blue LED ramp and write the data with other control data.

9.2.2.4 On or Off Data

There are a total of 48 bits of on or off data for the on or off control of each output. Select the on or off data of the LED lamp on or off status control and write the data.

9.2.2.5 Other Control Data

There are a total of 8 bits of control data to set the function mode for the status information data (SID) load control, LOD voltage setting, LSD voltage setting, and power save mode (PSM) explained in the Device Functional Modes section. Write the 8-bit control data for the appropriate operation of the display system with MC and BC data as the control data.

9.2.2.6 Grayscale Control

All constant-current outputs are controlled by the BLANK pin logic level. When BLANK is GND, all constant-current outputs are turned on except that the output is set to 0 in the 48-bit output on-off data latch. When BLANK is VCC, all outputs are forced off. The LED lamp grayscale can be controlled by the BLANK low pulse duration.

9.2.3 Application Curves

One LED connected to each output. BLANK low pulse duration = 40 ns.

figure38_sbvs241.gif
MCX = 5 BCX = 7Fh VLED = 4.2 V
VCC = 3.3 V SIDLD = LODVLT = LSDVLT = PSMODE = 0
Figure 38. OUTR0 Output Current Waveform
figure40_sbvs241.gif
MCX = 5 BCX = 7Fh VLED = 4.2 V
VCC = 3.3 V SIDLD = LODVLT = LSDVLT = PSMODE = 0
Figure 40. OUTB0 Output Current Waveform
figure39_sbvs241.gif
MCX = 5 BCX = 7Fh VLED = 4.2 V
VCC = 3.3 V SIDLD = LODVLT = LSDVLT = PSMODE = 0
Figure 39. OUTG0 Output Current Waveform