Renesas' 40 V input portfolio includes the ISL8541x family, the ISL8540 and ISL85403. The ISL85403 is a 40 V, 2.5 A synchronous buck or buck-boost controller with a high-side MOSFET and low-side driver integrated. The IC can also be configured in a standard buck configuration by disabling the low-side driver and connecting a Schottky diode instead. Similar to the 5 V regulators, this IC also integrates key features such as selectable PFM/PWM mode of operation, synchronization to external clock, adjustable soft-start, input supply tracking, programmable current limit and PGOOD/EN. In addition to these features, the ISL85403 also integrates a special mode of operation called the Automatic “Hold-up” mode. In this mode, the low-side driver is used to boost the input voltage above the UVLO threshold of the IC, if the input supply droops. This mode is ideal for automotive and various other battery powered applications, as it will extend battery life. In this operation mode, the buck portion of the regulator will be functioning in an asynchronous mode. This also features an adjustable switching frequency range of 200 kHz to 2.2 MHz to optimize for high efficiency or small output filter size.