5549 5MM LDR Photosensitive Resistor
When the surrounding light increases, the resistance across the sensor’s terminals decreases, allowing easy detection of brightness levels. Conversely, in darkness, the resistance rises significantly. This behavior makes the LDR light sensor a staple in modern electronics for tasks such as light measurement, motion detection, and automation.
Constructed using two Cadmium Sulphide (CdS) photo-conductive cells, this sensor exhibits a spectral response similar to that of the human eye. Its resistance drops rapidly with increasing light intensity, providing quick response and reliable output. Common applications include smoke detection, automatic lighting control, batch counting, and burglar alarm systems.
5549 5MM LDR Photosensitive Resistor
Available:In Stock
- Product SKU: KG1051
₹ 5
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Specification
Description
5549 5MM LDR Photosensitive Resistor
The 5549 5MM LDR Photosensitive Resistor is a high-quality LDR sensor that changes its resistance according to the intensity of ambient light falling on its surface. This LDR photoresistor (Light Dependent Resistor) is ideal for both indoor and outdoor light-sensing applications — from automatic streetlights to indoor night lamps.When the surrounding light increases, the resistance across the sensor’s terminals decreases, allowing easy detection of brightness levels. Conversely, in darkness, the resistance rises significantly. This behavior makes the LDR light sensor a staple in modern electronics for tasks such as light measurement, motion detection, and automation.
Constructed using two Cadmium Sulphide (CdS) photo-conductive cells, this sensor exhibits a spectral response similar to that of the human eye. Its resistance drops rapidly with increasing light intensity, providing quick response and reliable output. Common applications include smoke detection, automatic lighting control, batch counting, and burglar alarm systems.
Technical Details
- Diameter: 5mm
- Max Voltage: 150V DC
- Max Power: 100mW
- Operating Temp: -30°C to 70°C
- Spectrum Peak: 540nm
- Length with Terminals: 32mm
- Dark Resistance: 10MΩ (0 Lux)
- Light Resistance: 100–200KΩ (10 Lux)
- Model: 5549
Analog Applications
- Camera exposure control
- Auto slide focus – dual cell systems
- Photocopy machines – toner density detection
- Colorimetric test equipment
- Densitometers and exposure meters
- Electronic scales – dual cell balance
- Automatic gain control – modulated light sources
- Automated rear-view mirror brightness control
Digital Applications
- Automatic headlight dimmers
- Nightlight control circuits
- Oil burner flame detection
- Streetlight control systems
- Presence or absence detection (beam breaker)
- Position and proximity sensors
Features
- Accurate and consistent light detection
- Simple to interface with microcontrollers and analog circuits
- Compact 5mm package, easy to mount on breadboards or PCBs
- Fast response time with high safety and reliability
- Eco-friendly design with low power consumption
- Durable, low-cost, and easy to integrate into projects
Applications
- Automatic streetlight and nightlight systems
- Camera exposure and brightness control
- Flame and light detection in safety circuits
- Presence and position sensing in automation
- Light-activated alarms and security devices
- Solar-powered lighting and energy systems
- Brightness adjustment for displays and screens
- Industrial and smart lighting control systems
Specifications
| Model | Max Pressure (VDC) | Max Power (mW) | Ambient Temp (°C) | Spectral Peak (nm) | Bright Resistance (Ω) | Dark Resistance (MΩ) | Response Time (ms) |
|---|---|---|---|---|---|---|---|
| 5506 | 150 | 100 | -30~+70 | 540 | 4-7 | 0.5 | Rise:30 Fall:30 |
| 5516 | 150 | 100 | -30~+70 | 540 | 5-10 | 0.5 | Rise:30 Fall:30 |
| 5528 | 150 | 100 | -30~+70 | 540 | 10-20 | 1 | Rise:20 Fall:30 |
| 5537 | 150 | 100 | -30~+70 | 540 | 20-30 | 2 | Rise:20 Fall:30 |
| 5549 | 150 | 100 | -30~+70 | 540 | 100-200 | 10 | Rise:20 Fall:30 |
Drawing (mm)

Package Includes
- 1 × 5549 5MM LDR Photosensitive Resistor