Switched mode power supply for e.g. brightness-controlled LED array, employs optical feedback loop from secondary circuit

摘要

From the secondary side, a control voltage is supplied to a light source, an LED. This illuminates a photoresistor (LDR). The photoresistor forms part of a potential divider (Rv, Rp, LDR) for the intermediate circuit voltage. The divided potential, containing DC and AC components, is sent as the input signal (us) for the control circuit (AST).