The ISL85403 is a 40V, 2.5A synchronous buck or boost buck controller with a high-side MOSFET and low-side driver integrated. In buck mode, the ISL85403 supports a wide input range of 3V to 40V. In boost-buck mode, the input range can be extended down to 2.5V and output regulation can be maintained when V_IN drops below V_OUT, enabling sensitive electronics to remain on in low input voltage conditions.
The ISL85403 has a flexible selection of operation modes of forced PWM mode and PFM mode. In PFM mode, the quiescent input current is as low as 180µA (AUXVCC connected to VOUT). The load boundary between PFM and PWM can be programmed to cover wide applications.
The low-side driver can be either used to drive an external low-side MOSFET for a synchronous buck or left unused for a standard non-synchronous buck. The low-side driver can also be used to drive a boost converter as a preregulator followed by a buck controlled by the same IC, which greatly expands the operating input voltage range down to 2.5V or lower (Refer to “Typical Application Schematic III - Boost Buck Converter” on page 6).
The ISL85403 offers the most robust current protections. It uses peak current mode control with cycle-by-cycle current limiting. It is implemented with frequency foldback under current limit condition; also, the hiccup overcurrent mode is also implemented to guarantee reliable operations under harsh short conditions. The ISL85403 has comprehensive protections against various faults including overvoltage and over-temperature protections, etc.