TSL25911 Light Sensor

Introduction

We interact with different intensities and strengths of light in our daily activities. Therefore, detecting the amount of ambient light we interact with is very important. There are several ways this light can be detected, and the simplest form of sensor to do such tasks is the Light-Dependent Resistor (LDR). Besides that, many other improved methods exist that can be deployed. Such sensors are used in systems such as smartphones to detect brightness, which is suitable for human use. In your smartphone, you find an icon dabbed auto-brightness control. That is the sensor we are talking about. Such devices measure the system's brightness and control it correctly with the most ambient light. This article will focus on a simple ambient light control sensor built around the TSL259911 microcontroller.

What is the TSL25911 Microcontroller?

The TSL25911 microcontroller is a high-sensitivity light-to-digital converter that transforms light intensity into a digital signal output capable of direct I2C interface. The device combines one broadband photodiode (visible plus infrared) and one infrared-responding photodiode on a single CMOS integrated circuit. Two integrating ADCs convert the photodiode currents into a digital output representing the irradiance measured on each channel. This digital output can be input to a microprocessor where illuminance (ambient light level) in lux is derived using an empirical formula to approximate the human eye response. The TSL2591 supports a traditional level style interrupt that remains asserted until the firmware clears it.

The TSL2511 Light Sensor Module Components

Below are the necessary components for the Circuit:

• 22u Unpolarized capacitor C1, C2 C_0805_2012Metric
• LED Light emitting diode D1 LED_0603_1608Metric
• Conn_01x05_Pin Generic connector, single row, 01x05, script generated J1 JST_EH_B5B-EH-A_1x05_P2.50mm_Vertical UM6K34NTCN R1, R4 TRANS_UM6J1_ROM
• 4.7k Resistor, small US symbol R2, R3, R5, R6 R_0402_1005Metric
• 1k5 Resistor R7 R_0402_1005Metric
• TSL25911FN U1 SON-06-FN_2000X2400_AMS
• AMS1117-3.3 1A Low Dropout regulator, positive, 3.3V fixed output, SOT-223 U2 SOT-223-3_TabPin2

The TSL2511 Light Sensor Module

The module has the following features:

• Adopts TSL25911FN, measures infrared plus visible light.
• Embedded ADC, direct light intensity signal output to I2C interface, less noise jamming.
• High sensitivity up to 188uLux, wide dynamic range up to 600M:1.
• Embedded infrared-responding photodiode allows precise measuring even in a strong infrared noise environment.
• Provides interrupt output with programmable upper and lower thresholds.
• Onboard voltage translator, compatible with 3.3V/5V operating voltage

The TSL2511 Light Sensor Module Pinout

• VCC- Provides power for the module, Connecting to the 5V pin of the Arduino.
• GND- Ground Connected to the Ground pin of the Arduino.
• SCL_EXT-Serial Clock is used to provide a clock pulse for I2C Communication.
• SDA_EXT- Serial Data Used for transferring Data through I2C communication.
• INT– Interrupt Pin.

TSL25911 Sensor Module Circuit Diagram

The power circuit comprises an AMS1117-3.3 LDO voltage regulator, which steps input DC to output 3.3V at 1A, which is necessary to power the primary circuit. It also has a level shifter circuit built around the UM6K34NTCN N-channel MOSFET transistor. The circuit also has several by-pass capacitors.

Where and How Do You Order Such Boards?

Looking at the PCBWay website, I discovered three critical features while ordering your PCB for fabrication and assembly. Through PCBWay, you can order a turkey project where PCBWay supplies the parts, a kit where the customer supplies all the parts or a combo where the customer supplies some parts while PCBWay does the rest. This service depends on the customer's preference, thus making PCBWay one of the most flexible fabrication houses I can always recommend to a friend.

Schematics