White LED driver constant current non isolated transfomerless 230V circuit diagram

Download: VIPower: Offline constant current LED driver using VIPer12/22A http://www.st.com/web/en/resource/technical/document/application_note/CD00012203.pdf

A lower cost alternative to the isolated VIPer12A power supply is to use the VIPer22A in a non-isolated transformerless Buck configuration. The White LED driver constant current non isolated 230V (90-246 V AC) circuit diagram uses fewer and less expensive parts for systems that do not require safety isolation.

Non-isolated buck configuration scircuit diagram C1, L0, and C2 form an EMI filter to meet emission standards. D6, C3 maintain voltage for Vdd. L1 and C6 form the output filter to average the DC output. The output is voltage regulated at 10V by the zener diode DZ1. R2 drops the voltage and sets the current to approximately 330mA. A different value resistor can be used to set the current to a value up to 370mA which is the limiting factor of L1, the output inductor.

This unit will drive 2 LEDs or 1 LED by cutting one jumper before use. To drive 1 LED only, the jumper can be cut, placing a second resistor in series with the output to drop additional voltage. This is not as efficient as the previous design but simpler and less expensive. The output is set to 10V because that is the minimum output voltage that will drive the VIPer22A with these minimum parts. With the addition of an inductor, 2 of 1N4005 and a small capacitor, a lower voltage can be designed to increase the efficiency.