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

Package Options

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

1 Features

  • Internal Power-On Reset
  • Active Low Reset
  • Internal Precision Oscillator
  • Variable Dim Rates
    (From 6.25 ms to 1.6 s; 160 Hz to 0.625 Hz)
  • 16 LED Drivers (Multiple Programmable States: ON, OFF, Input, and Dimming at a Specified Rate)
  • 16 Open-Drain Outputs Capable of Driving up to 25 mA per LED

2 Applications

  • Customized Flashing LED Lights for Cellular Phones
  • Portable Applications
  • Digital Cameras
  • Indicator Lamps
  • General Purpose I/O Expander
  • Toys

3 Description

The LP3943 is an integrated device capable of independently driving 16 LEDs. This device also contains an internal precision oscillator that provides all the necessary timing required for driving each LED. Two prescaler registers, along with two PWM registers, provide a versatile duty-cycle control. The LP3943 contains the ability to dim LEDs in SMBUS/I2C applications where it is required, to cut down on bus traffic.

Traditionally, dimming LEDs using a serial shift register such as 74LS594/5 requires a large amount of traffic on the serial bus. The LP3943 instead requires only the setup of the frequency and duty cycle for each output pin; from then on, only a single command from the host is required to turn each individual open drain output to an ON or OFF state, or to cycle a programmed frequency and duty cycle. Maximum output sink current is 25 mA per pin and 200 mA per package. Any ports not used for controlling the LEDs can be used for general purpose input/output expansion.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LP3943 WQFN (24) 4.00 mm × 4.00 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit

LP3943 20079601.gif