SNVS256D Novmeber   2003  – November 2016 LP3943

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
    6. 6.6 I2C Interface (SCL and SDA Pins) Timing Requirements
    7. 6.7 Typical Characteristic
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
    5. 7.5 Programming
      1. 7.5.1 I2C Data Validity
      2. 7.5.2 I2C START and STOP Conditions
      3. 7.5.3 Transferring Data
      4. 7.5.4 Auto Increment
    6. 7.6 Register Maps
      1. 7.6.1 Binary Format for Input Registers (Read-only)—Address 0x00 and 0x01
      2. 7.6.2 Binary Format for Frequency Prescaler and PWM Registers — Address 0x02 to 0x05
      3. 7.6.3 Binary Format for Selector Registers — Address 0x06 to 0x09
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Reducing IQ When LEDs are OFF
      3. 8.2.3 Application Curve
    3. 8.3 System Examples
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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8 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.

8.1 Application Information

The LP3943 is a 16-channel LED controller which has 16 low-side current switches. Each switch can control the LED current in its respective LED or LEDs by modulating its duty cycle and frequency.

8.2 Typical Application

LP3943 20079601.gif Figure 10. LP3943 Typical Application

8.2.1 Design Requirements

For typical RGB LED light-driver applications, use the parameters listed in Table 14.

Table 14. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Minimum input voltage 2.3 V
Typical output voltage 5 V
Output current 20 mA

8.2.2 Detailed Design Procedure

8.2.2.1 Reducing IQ When LEDs are OFF

In many applications, the LEDs and the LP3943 share the same VDD, as shown in Figure 10. When the LEDs are off, the LED pins are at a lower potential than VDD, causing extra supply current (ΔIQ). To minimize this current, consider keeping the LED pins at a voltage equal to or greater than VDD.

LP3943 20079614.png Figure 11. Methods to Reduce IQ When LEDs are in OFF State

8.2.3 Application Curve

LP3943 D001_SNVS256.gif Figure 12. Typical LED Switch Resistance

8.3 System Examples

LP3943 20079615.gif Figure 13. LP3943 With 5-V Booster
LP3943 20079616.gif Figure 14. LP3943 Driving RGB LED as a Flash