An integrated LDR replaces the entire timer-and-photocell assembly with one sealed component — and removes the commissioning errors that come with it. This guide covers how to specify one for Indian outdoor conditions, where integrated sensors go wrong, and what surge rating you actually need on a pole.
A dusk to dawn LED driver has a light sensor — a Light Dependent Resistor, or LDR — built into the driver housing itself. When ambient light falls at sunset, the driver switches the LED on. When it rises at sunrise, the driver switches it off. That is the entire mechanism.
What it replaces is a timer, a separate photocell box on the pole, and the relay wiring between them. Each of those is an additional component that can fail, an additional enclosure that can admit water, and an additional thing to install and commission on site. It also replaces the recurring human error of a timer that was set once and never adjusted as sunset moved through the year — lights burning at 7am in December, or coming on an hour late in June.
For street lighting, gate-pillar lights, security floodlights and rural signage, this is usually the correct architecture. There is no scheduling to get wrong.
Dusk-to-dawn drivers live almost exclusively on outdoor and rural feeds — precisely the supply that swings furthest from nominal. A driver rated 220–240V is the wrong product for a village pole-top. Our LR series operates across 120–300V AC for this reason.
Ask: what is the operating input range, and is that the design range or the survival range?By definition these drivers are outdoors and usually on poles, which is the most surge-exposed position in any lighting installation. A dusk-to-dawn driver without meaningful surge protection is a driver that will be replaced. Our LR series carries 6kV per IEC 61000-4-5; for high-exposure sites, pair it with a 10kV or 20kV SPD.
Ask: what surge standard is it tested to, and at what level?An integrated LDR only works if light reaches it. A driver buried deep inside an opaque luminaire housing, or one mounted where a building or tree canopy shades it at dusk, will switch late or not at all. Equally, a sensor positioned where a neighbouring light shines directly on it can hold the fixture off all night.
Check: the physical mounting orientation before committing to an integrated-sensor design.Constant-current drivers specify an output voltage range and a current. The LED array's forward voltage must fall inside that range. A 50W driver offering 24–45V at 1.5A will not correctly drive an array that sits at 60V, even though the wattage appears to match — which is why our 50W and 100W models each offer multiple output configurations.
Ask: what is the LED array's forward voltage, not just its wattage?Pole-top fixtures cycle through heat, condensation, dust and driving rain. Potting matters more than the IP number on the datasheet — a nominally sealed but unpotted driver will admit moisture through the cable gland eventually. The LR encapsulated series is potted to IP-65.
Ask: is it potted or merely enclosed?The encapsulated LR series spans 36W to 100W, all with built-in LDR, IP-65 potting, 6kV surge protection per IEC 61000-4-5, a 120–300V AC operating range and a two-year warranty. Full specifications on the dusk to dawn driver product page.
| Model | Wattage | Output | Construction |
|---|---|---|---|
| SP-111LR | 36 W | Constant current | Encapsulated, IP-65 |
| SP-108LR | 50 W | 24–45V · 1.5A or 52–66V · 800mA | Encapsulated, IP-65 |
| SP-107LR | 50 W | Constant current | Open frame |
| SP-110LR | 60 W | Constant current | Encapsulated, IP-65 |
| SP-109LR | 100 W | 30–45V · 2.7A / 50–75V · 1.5A / 90–130V · 700mA | Encapsulated, IP-65 |
The SP-108LR at 50W is the most commonly specified model for street lights, security floodlights and pole-mounted commercial fixtures. The SP-109LR at 100W covers main-road street lighting, high-mast fixtures and large floodlights.
A dusk to dawn LED driver is an LED power supply with a light sensor, usually a Light Dependent Resistor (LDR), built into the driver housing. It switches the light on automatically when ambient light falls at sunset and off again at sunrise, with no external timer, separate photocell or relay wiring. It is used for street lights, security floodlights, gate pillar lights and rural signage where manual or scheduled switching is impractical.
A timer switches at fixed clock times and must be reset as sunset and sunrise move through the year, otherwise lights burn into the morning in winter or come on late in summer. A dusk to dawn driver responds to actual ambient light, so it tracks the seasons automatically. It also eliminates the separate photocell enclosure and relay wiring a timer-based installation requires, removing components that can fail or admit water.
Dusk to dawn drivers are typically installed on outdoor and rural feeds where supply voltage swings well outside nominal. A driver rated only 220–240V AC is unsuitable for most Indian pole-top installations. Look for a wide operating range — the Smooth Power LR series operates from 120V to 300V AC — and confirm whether the quoted figure is the design range or merely the survival range.
Yes. These drivers are by definition outdoors and usually pole-mounted, which is the most surge-exposed position in a lighting installation. The Smooth Power LR series is rated to 6kV per IEC 61000-4-5. For high-exposure sites — long overhead distribution runs, rural pole-tops, coastal and heavy-monsoon regions — pair the driver with a separate 10kV or 20kV surge protection device.
Smooth Power manufactures the encapsulated LR series from 36W to 100W: SP-111LR (36W), SP-108LR (50W), SP-110LR (60W) and SP-109LR (100W), plus the SP-107LR (50W) in an open-frame version. The 50W SP-108LR is the most commonly specified for street lights and security floodlights; the 100W SP-109LR covers main-road street lighting and high-mast fixtures.
Smooth Power Private Limited manufactures dusk to dawn LED drivers with integrated LDR sensors at its Sahibabad Industrial Area plant in Ghaziabad, Uttar Pradesh, in wattages from 36W to 100W with IP-65 potting, 6kV surge protection to IEC 61000-4-5 and a 120–300V AC operating range. BIS registration R-81008324, GSTIN 09AAZCS0655B1Z2, two-year warranty.
Send your fixture specification, wattage and current target, and compliance requirement to sales@smoothpower.in or call +91-82872 62090. Ask for engineering rather than sales.
Our factory is at Plot No A-2/77, Site-IV, Sahibabad Industrial Area, Ghaziabad 201010, with a second unit at Durga Industrial Park. If you are in Delhi NCR, come and look at the line. See also our guide to choosing an LED driver manufacturer in India.