IACS CO., LIMITED (Yiwu Fuwei e-commerce firm)

The circuit drives a high-power white LED (WLED) that turns off the LED when the temperature is too high and the thermistor is open or shorted. If you work outside the extreme operating temperature range, the life of any IC will be shortened. When the junction temperature of the chip exceeds a certain value, it will be completely damaged. Philips Lumileds LUXEON high-power LED modules are less heat-generating because they are fabricated on thermally enhanced substrates. This base material improves thermal performance and allows continuous operation at high currents to meet the requirements of high brightness illumination. However, for applications such as camera flash, additional thermal protection is required to avoid damage to the device during continuous operation.

The circuit in Figure 1 includes a charge pump regulator (IC1) suitable for camera flash applications that provides regulated current for up to eight white LEDs (WLEDs). Parallel all 8 drivers to deliver up to 480mA for a single 1W, LUXEON Star high power WLED module. When the open-drain input EN is pulled to ground, IC1 enters the shutdown mode.

A single thermistor and a dual open-drain comparator (IC2) with an internal reference can be used to create a compact and cost-effective thermal shutdown circuit. When VTHERM falls below the 1.2V internal reference voltage, Comparator A pulls EN low to ground. This is done when the thermistor (R2) is hot. Comparator B is used to provide an open-circuit fail-safe feature, ie when the contact of the thermistor is disconnected, EN will be pulled low. When an open circuit fault occurs in the thermistor, VTHERM is pulled high by R1, causing comparator B to pull EN low. The resistor divider R3-R4 sets the threshold voltage for the open fault, and the resistor R1 and the thermistor R2 set the thermal shutdown threshold.

Yiwu Fuwei e-commerce firm (IACS Co., Limited) is a very professional Led manufacturer who produces high quality outdoor led light. Our popular products are solar led lights, UFO lights, underwater lights and so on. If you have any question about the led product, please feel free to contact us.