Fuser lamp

Circuit Protection of Fuser Lamp

Design Notes:

Protection Application:
After the toner is applied to the paper, it needs to be dried. This is accomplished by the fuser lamp. The lamp operates at 120VAC or 250VAC and is typically rated at 500W to 600W. The control signal from the heater control circuit is typically low voltage (< 9VDC).
Solution Description:
As shown at the left, a triac (gate activated by optocoupler) or sensitive triac (gate activated by microcontroller) can be used to control the function of the fuse lamp. The gate is activated by a signal from the heater control circuit. The example is for a 600W bulb.
Companion Solutions:
The triac family is available in a wide range of SMD and leaded form factors. Also, there is a broad range of electrical characteristics to satisfy many circuit conditions.
Regulatory Issues:
Does not apply.
Unique Features:
Does not apply.
Application Warnings:
Make sure to select the Triac such that the current flowing through it and the fuser lamp is no more than 70% of its Itrms specification.