3-CH, 18V, Synchronous Step-Down Converter

The RT7273 features three synchronous wide input range high efficiency Buck converters. The converters are designed to simplify its application while giving the designer the option to optimize their usage according to the target application.

The converters can operate in 5V, 9V or 12V systems and have integrated power transistors. The output voltage can be set externally using a resistor divider to any value between 0.8V and the input supply minus 1V. Each converter features an enable pin that allows a delayed start-up for sequencing purposes, a soft-start pin that allows adjustable soft-start time by choosing the soft-start capacitor, and a current limit pin (RLIMx) to adjust current limit by selecting an external resistor. The COMP pin allows optimizing transient versus dc accuracy response with a simple RC compensation.

The switching frequency of the converters can either be set with an external resistor connected to ROSC pin or be synchronized to an external clock connected to SYNC pin if needed. The switching converters are designed to operate from 300kHz to 2.2MHz. The converters operate with 180° phase between CH 1 and CH 2, CH 3 (CH 2 and CH 3 ran in phase) to minimize the input filter requirements.

The RT7273 also features a low power mode enabled by an external signal, which allows for a reduction on the input power supplied to the system when the host processor is in stand-by (low activity) mode.