The controller boasts low EMI emission by zero voltage switching and various safety protection circuits. The R1700 is powered directly from mains and converts its primary power source into a voltage suitable to drive LEDs. The IC is optimized for non-isolated LED driver circuits and has a wide input voltage range up to 650V to tolerate peaks in the supply voltage caused by switching inductive loads and to have enough safety margin.
Ricoh’s solution uses a unique one stage switching conversion with an advanced buck-boost (inverting) topology. Additionally, an edge resonance controlled Zero Voltage Switching (ZVS) circuit allows a high operating frequency. These two features accept the use of smaller and less bulky components which makes the application suitable for integration in regular but also small and thin sized lighting fixtures. Compared to conventional circuits, a board-space reduction of 70% and height reduction of 50% can be achieved, claims the company. LED brightness level is dimmable from 100% to 5% by connecting a PWM signal to the DIM input. As an alternative option one could consider adding the R1580 constant current driver into the circuit. This IC converts a PWM signal into a linear dimming signal, the main advantages of this method is that the LED driver MOSFET is not continuously switching which supresses the harmonic current and EMI emission and results in a flicker-free LED operation.
Ricoh Europe – www.ricoh-europe.com