TSL235R Light to Frequency Converter

TSL235R Light to Frequency Converter is a high-sensitivity silicon photodiode combined with a current-to-frequency converter that outputs a pulse train with a frequency directly proportional to light intensity. Consequently, this specialized sensor eliminates the need for complex analog-to-digital (ADC) conversion, as a simple microcontroller timer can read the digital output signal directly. The device features a wide dynamic range and provides stable performance across a broad spectrum of visible and near-infrared light. Furthermore, its high-resolution output allows for precise measurement even in low-light conditions. Therefore, you should choose the TSL235R when your project requires an accurate, digital light sensing solution with minimal peripheral circuitry.

Key Features:

• High-Resolution Conversion: The IC converts light intensity to a digital square wave, offering much higher resolution than standard analog photocells.
• Direct Microcontroller Interface: The digital output communicates directly with any digital input pin, simplifying the firmware development process.
• Wide Dynamic Range: This sensor accurately measures light across a range of 1 Hz to 500 kHz, covering several orders of magnitude of irradiance.
• Single-Supply Operation: It operates efficiently on a wide voltage range, ensuring compatibility with both 3.3 V and 5 V logic systems.
• Commendable Stability: The device includes internal temperature compensation to maintain accuracy across varying environmental conditions.

Technical Specifications:

• Supply Voltage (V_DD): 2.7 V to 5.5 V
• Output Frequency Range: 1 Hz to 500 kHz (typical)
• Irradiance Responsivity: ≈ 0.6 kHz/(mW/cm²) at λ_p = 635 nm
• Peak Spectral Response (λ_p): 635 nm (Sensitive from 320 nm to 1050 nm)
• Supply Current (I_DD): Typically 2 mA (≤ 3 mA max)
• Full-Scale Frequency Accuracy: ±20% (Unit-to-unit variation)
• Nonlinearity: ≤ 0.2% at 100 kHz

Mechanical Specifications:

• Package Type: 3-Lead Side-Looker (Plastic Package)
• Lead Finish: Solder Dipped or Tinned
• Lens Type: Clear Plastic Lens for high light transmission
• Durability: Solid-state design provides resistance to mechanical shock and vibration.

Dimensions:

• Package Height: ≈ 4.6 mm
• Package Width: ≈ 4.6 mm
• Package Thickness: ≈ 1.8 mm
• Lead Length: ≈ 13.0 mm
• Pin Pitch: 1.27 mm (Standard for side-looker packages)

Pinout and Wiring:

• Pin 1 (GND): Connect this pin to the common circuit ground (0 V).
• Pin 2 (V_DD): Supply voltage pin; connect to a regulated 2.7 V to 5.5 V source.
• Pin 3 (OUT): Digital square wave output; connect this to a microcontroller interrupt or timer input pin.
• Wiring Tip: Place a 0.1 μF ceramic capacitor close to the V_DD and GND pins to minimize power supply noise.

Datasheet Reference:

• Download ams TSL235R Light to Frequency Converter Datasheet

Commonly Used in:

• Ambient Light Monitoring: Systems that adjust display brightness based on surrounding lighting conditions.
• Educational Robotics: Simple light-following or obstacle-detection sensors for student projects.
• Optical Encoders: Detecting movement or rotation by measuring pulses of light through a slotted disk.

Applications:

• Chemical Analysis: Measuring the clarity or color density of liquids in portable lab equipment.
• Flash Photography: Controlling exposure time by measuring the total light energy delivered.
• Street Light Controllers: Automating the activation of outdoor lighting at dusk and deactivation at dawn.
• Proximity Sensing: Detecting the presence of objects in industrial counting and sorting systems.

Equivalent Models:

• TSL237R: A similar model with higher sensitivity, however, it may require different scaling factors in software.
• TSL230R: A programmable version that allows the user to scale the output frequency electronically.
• TSL245: An infrared-to-frequency converter that shares the same digital output architecture for IR sensing.

Package Includes:

• 1 x TSL235R Light to Frequency Converter (3-Pin Side-Looker)