The RT8458A is a PWM controller with an integrated high side gate driver. It is used for step down converters by well controlling the external MOSFET and regulating a constant output current. The output duty cycle of the RT8458A can be up to 100% for wider input voltage application, such as E27 and PAR30 off-line LED lighting products.
The RT8458A also features a 47kHz fixed frequency oscillator, an internal -220mV precision reference, and a PWM comparator with latching logic. The accurate output LED current is achieved by an averaging current feedback loop and the LED current dimming can be easily controlled via the ACTL pin. The RT8458A also has multiple features to protect the controller from fault conditions, including Under Voltage Lockout (UVLO), Over Current Protection (OCP) and Over Voltage Protection (OVP). Additionally, to ensure the system reliability, the RT8458A is built with the thermal protection function.
The RT8458A is housed in a TSOT-23-6 package. Thus, the components in the whole LED driver system can be made very compact.