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Reference Design for a number of LED Ring Lighting Patterns

Description

This reference design enables human-machine interface scenarios by having an LED ring that utilizes two LP5024 LED drivers to produce vivid lighting patterns. Design helps you to resolve common challenges for end equipment with complicated lighting patterns and constant voltage supply. This design may also adjust LP5024 brightness with analog dimming without impacting the sunlight pattern contrast ratio on dynamic ambient light sense.

Features:

  • Vivid Lighting Patterns With 12-Bit, 29-kHz PWM Dimming Through and I2C Interface
  • Ultra-Low Standby Current Down to 10 uA With Automatic Power Saving Mode
  • Programmable Banks (R/G/B) for Easy Software Charge of Each Color
  • Dynamically Adjusts Brightness on Ambient Light Sense

Applications:

  • Smart Speaker (With Voice Assist)
  • Appliances User Interface and Connectivity Modules
  • Video Doorbell
  • Electronic Smart Lock
  • STB and DVR
  • WLAN/WIFI Access Point
  • Virtual- and Augmented-Reality Headsets and Glasses
  • Printers
  • Video Game Console
  • Home Theater-in-a-Box (HTiB)

  1. System Description

This may be the design guide for that Various LED Ring Lighting Patterns Reference Design, making the vivid lightings pattern on the LED ring with 2 LP5024 devices. In this reference design, LP5024 linear LED drivers are used to drive 16 RGB LED modules with constant current control. OPT3001 senses the ambient light dynamically. The MSP432P401R LaunchPad sends the control signal to regulate LP5024 analog current and generate the various lighting patterns.

1.1 Key System Specifications

Table 1. Key System Specifications

PARAMETER SPECIFICATIONS
Input voltage range 3 V to five.5 V
Output current 8 mA/channel maximum
LED number 16 RGB
LED type 19-337/R6 GHBHC-A01/2T
Lighting pattern style 7
Analog dimming control range 1% to 100 %

 

2. System Overview

2.1 Block Diagram

Figure 1. TIDA-050011 Block Diagram

2.2 Design Considerations

In this reference design, two 24-channel, 12-bit, PWM ultralow-quiescent-current, I2C RGB LED drivers (LP5024) are utilized to drive a 16-RGB-LED module with constant current control and smooth dimming effect. The LP5024 devices improve the consumer experience in color mixing and brightness control for live effects and coding efforts. The optimized performance for RGB LEDs makes the LP5024 an excellent fit for human-machine interaction applications. OPT3001 senses the ambient light dynamically. The MSP432P401R LaunchPad sends the control signal to regulate LP5024 analog current and create the various lighting patterns.

Several considerations are taken into consideration with this particular design:

  • LED map (ring) for meeting the advantages of popular human-machine interaction style.
  • LED size, numbers and also the diffuse design for meeting lighting pattern uniformity.
  • Analog dimming within the difference ambient light lux without losing dimming resolution in lighting pattern.

These considerations affect most human-machine interaction end equipment with night and day vision designs in some manner, however the designer must decide the particular considerations to take into account for a specific design.

2.3 Highlighted Products

The following highlighted products are utilized in this reference design. The important thing features for selecting the devices for this reference design are outlined within the following subsections. For the complete details of the highlighted devices, make reference to their respective product data sheets.

2.3.1 LP5024-24-CHANNEL, 12-Bit, PWM Ultralow-Quiescent-Current, 12 RGB LED Diver

The LP5024 system is an 24-channel constant current-sink LED driver. The LP5024 device increases the user experience colored mixing and brightness control, from both live effects and coding efforts. The optimized performance for RGB LEDs causes it to be a potential choice for human-machine-interaction applications.

The LP5024 device controls each LED output having a 12-bit PWM resolution at 29-kHz switching frequency, which will help acquire a smooth dimming effect and eliminates audible noise. The independent color mixing and brightness control registers result in the software coding straightforward. When targeting fade-in, fadeout type breathing effect, the worldwide R, G, B bank control reduces the microcontroller loading significantly. The LP5024 device also implements a PWM phase-shifting function in lowering the input power budget when LEDs turn on simultaneously.

2.3.2 SimoleLink MSP432P401R LaunchPad Development Kit

The SimpleLink MSP-EXP432P401R LaunchPad development kit enables someone to develop high-performance applications that benefit from low-power operation. This kit features the MSP432P401R LaunchPad, with a 48-MHz Arm Cortex-M4F, 80-μA/MHz active power and 660-nA RTC operation, 14-bit 1- MSPS differential SAR ADC, and AES256 accelerator. All pins of the MSPEXP432P401R device are fanned out for simple access. These pins allow it to be easy to connect 20-pin and 40pin BoosterPack modules that add more functionality including Bluetooth low energy, Wi-Fi wireless connectivity, and much more.

2.3.3 OPT3001 Digital Ambient Light Sensor (ALS) with High-Precision Human-Eye Response

The OPT3001 is a sensor that measures the concentration of visible light. The spectral response of the sensor tightly matches the photopic response of the human eye and includes significant infrared rejection.

The OPT3001 is a single-chip lux meter, measuring the intensity of light as visible by the human eye. The precision spectral response and powerful IR rejection from the device enables the OPT3001 to accurately meter the intensity of light as seen by the eye no matter source of light. The strong IR rejection also helps with maintaining high accuracy when industrial design requires mounting the sensor under dark glass for aesthetics. The OPT3001 is made for systems that create light-based experiences for humans, as well as an ideal preferred alternative to photodiodes, photoresistors, or any other ambient light sensors with less human eye matching and IR rejection.

Measurements can be made from 0.01 lux up to 83 k lux without manually selecting full-scale ranges by using the built-in, full-scale setting feature. This capability allows light measurement on the 23-bit effective dynamic range.

2.4 System Design Theory

Two 24-channel, 12-bit, PWM ultralow-quiescent-current, I2C RGB LED drivers (LP5024) are utilized to drive a 16-RGB-LED module with constant current control and a smooth dimming effect. OPT3001 senses the ambient light dynamically. The MSP432P401R LaunchPad sends the PWM control signal to regulate LP5024 analog current and refresh the LP5024 device registers to create the various lighting patterns.

2.4.1 Power Design Theory

The LEDs (VLED) are powered by the external DC power directly or 3.3 V in the MSP432P401R LaunchPad through J8 ( VINSEL ).

The 3.3-V blue and green LEDs, which forward voltage may use separate power from the red LED because the red LED forward voltage is 1.8 V. The lower input voltage for the red LED cuts down on the power dissipation in the LED driver. J7 may be the configuration jumper.

LP5024 supports 1.8-V, 3.3-V, and 5-V I2C communication logic leves, which means the difference power rail can be used in VCC, I2C interface and VLED. The device is also configured through J1, J2, and J3.

Figure 2. Power Design

2.4.2 LED Deign

16 RGB LED modules were placed because the LED rings for that popular human-machine interaction style. This design uses two LP5024 devices.

Figure 3. LED Design

2.4.2.1 LED Current

The maximum current of every LED is 8 mA.

The constant-current value (ISET) of 24 channels is set by a single external resistor, RIREF. The value of RIREF could be calculated by Equation 1.

VIREF

RIREF=KIREF ×

ISET

where:

  • KIREF = 105
  • VIREF = 0.7 V (1)

The maximum current of every LED is 8 mA.

Select R4, R5, R6, R7 with a value of 5.1 kOhm.

2.4.2.2 LP5024 Analog Dimming Circuit Design

The source current of IREF pin determines the LP5024 constant-current value (ISET). The input PWM signal filters it as DC voltage with a large capacitor. The IREF is calculated from equations based on the schematic.

 

where

  • K = R5 / (R4 + R5)
  • D is duty cycle of the PWM Make R4 = R5, then K = Half.

Ioutx K IREF u VIREF uD

R4 u 1 D

2.4.3 OPT3001 Design

Use the OPT3001 typical application to measure ambient light lux. Make sure that the C1 capacitor is positioned near to the VDD pin.

Figure 5. OPT3001 Design

2.4.4 Relation Between Pattern Brightness and Ambient Light Lux

When lux is 0, the minium brightness is 1%. When lux is higher than 2000, the utmost brightness is 100%. When the lux is between 0 and 2000, the brightness includes a linear relation with the lux.

Courtesy: www.ti.com