This Product Selection Guide contains information to help select products in the Optical Sensors - Photo Detectors - CdS Cells category on DigiKey.com
Cadmium sulfide (CdS) photodetectors, also known as photoresistors, light-dependent resistors (LDRs), or photo-conductive cells are high resistance semiconductors that operate as light-controlled variable resistors. The resistance of a photoresistor decreases with increasing incident light intensity. Photoresistors are selected by cell resistance, max voltage, and rise and fall times.
SelectionCharacteristics
Specifications to determine which CdS cell photo detector is right for your application.
Wavelength: The peak wavelength of the sensed light range spectrum.
Voltage - Max: Typically this represents the maximum voltage rating to which a device will meet its given specifications. Exceeding this voltage rating may damage the device and other system components.
Rise Time (Typ): The typical delay between application of light and a sensor’s resistance approaching its final value, under manufacturer-defined test conditions.
Fall Time (Typ): Typical time delay between removal of a test illuminance and recovery of photocell resistance.
Cell Resistance (Min) @ Dark: Specified minimum device resistance under zero-light conditions.
Cell Resistance @ Illuminance: Expected range of photocell resistance (Min ~ Max) at specified incident illuminance level.
Operating Temperature: Recommended operating temperature, typically given in a range or as a maximum. Exceeding these temperatures may affect performance or damage the device and other system components.
Mounting Type: Indicates how the device is attached.
Package/Case: Indicates the type of protective case used on an electronic component to allow easy handling, installation, and protection. This selection was determined to be the closest industry standard applicable to the suppliers device packaging. Typically it is best to check the actual dimensions from the datasheet rather than depend on this terminology when designing your circuit.
Supplier Device Package: This is what the manufacturer calls the package of this device. They are manufacturer specific. It is typically best to use the actual dimensions from the datasheets rather than to go by this terminology when designing your circuit.
ProductExamples
| MFR PART # | PDV-P8104 |
|---|---|
| DIGI-KEY PART # | PDV-P8104-ND |
| MANUFACTURER | Advanced Photonix |
| DESCRIPTION | CdS Cells 520nm 27 ~ 60kOhms @ 10 lux |
| DATASHEET | Click Here |
| MFR PART # | 161 |
|---|---|
| DIGI-KEY PART # | 1528-2141-ND |
| MANUFACTURER | Adafruit Industries LLC |
| DESCRIPTION | PHOTO CELL (CDS PHOTORESISTOR) |
| DATASHEET | Click Here |
MediaLinks
Articles
Light Sensors: An Overview
The Use of Sensors in Commercial Lighting
Articles on CdS Photo Detector Cells