SNVS500C July   2007  – November 2016 LP5524

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 LED Driver Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 LED
      2. 7.3.2 LED Headroom Voltage
      3. 7.3.3 LED Outputs
      4. 7.3.4 PWM Brightness Control
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable Mode
      2. 7.4.2 ISET Pin
  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 Recommended External Components
          1. 8.2.2.1.1 Input Capacitor, CIN
          2. 8.2.2.1.2 Current Set Resistor, RISET
      3. 8.2.3 Application Curves
  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 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 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 LP5524 device provides an easy-to-use solution for driving up to 4 indicator LEDs.

8.2 Typical Application

LP5524 typ_app_snvs500.gif Figure 5. LP5524 Typical Application

8.2.1 Design Requirements

For typical LED-driver applications, use the parameters listed in Table 1.

Table 1. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Minimum input voltage 2.7 V
ISET resistance 34 kΩ
Output current 60 mA
Maximum LED Vƒ 2.625 V

8.2.2 Detailed Design Procedure

8.2.2.1 Recommended External Components

8.2.2.1.1 Input Capacitor, CIN

Although not required for normal operation, a capacitor can be added to VIN to reduce line noise. TI recommends using a surface-mount multi-layer ceramic capacitor (MLCC). MLCCs with a X7R or X5R temperature characteristic are preferred.

Table 2. List Of Recommended External Components

PARAMETER VALUE UNIT TYPE
CIN VDD bypass capacitor 100 nF Ceramic, X7R or X5R
RISET Current set resistor for 15.9-mA LED current 32.4 kΩ 1%
LEDs User defined

8.2.2.1.2 Current Set Resistor, RISET

If other than 5 mA current is required, RISET resistor can be used to adjust the current. For a 15.9-mA current a 32.4 kΩ resistor is required. Accuracy of the resistor directly effects to the accuracy of the LED current. TI recommends accuracy of 1% or better.

Equation 2. IDX = 515 / RISET (Amps)

Table 3. Recommended E96 Series (1% Tolerance) Current Set Resistors

RISET (kΩ) IDX (mA) RISET (kΩ) IDX (mA)
169 3.0 34.0 15.1
127 4.1 32.4 15.9
102 5.0 30.1 17.1
84.5 6.1 28.7 17.9
73.2 7.0 26.7 19.3
64.9 7.9 25.5 20.2
56.2 9.2 24.3 21.2
51.1 10.1 23.2 22.2
46.4 11.1 22.1 23.3
42.2 12.2 21.5 24.0
39.2 13.1 20.5 25.1
36.5 14.1

8.2.3 Application Curves

LP5524 30007629.png
Figure 6. PWM Response (Both Channels)
LP5524 30007627.png
Figure 7. PWM Response (Single Channel)