Hello,
I have an LED component in which the input is limited to a maximum of 150 V DC from + to earth Ground per UL, but be greater than 50 V in order to operate. The voltage drop across the LED itself will be on the order of 40 V. Looking at the example circuit for the LM3444, if we were connected to 120 V, 60 Hz mains input, then the peak voltage at Vbuck could be around 170 V and if assuming a worst case of 135 VAC, the Vpeak could be 190 V. In both of these scenarios, the Vbuck would violate the 150 VDC maximum from the + side of the LED to earth ground (heat sink in this case or housing of the LED). What are my options for limiting the Vbuck voltage to below 150 VDC?
The current passing through the LED will be 2.5 to 3.0 Amps and the voltage drop across the LED is 40 VDC.
Is the only option available, to use a transformer at the mains input or can I use some sort of Zener diode circuit to help clamp the Vbuck value to below 150 VDC?
See the attached image for reference.