Loss of regulation due to drooping input voltage is a common problem in automotive applications. Such input dropouts – commonly called ‘cold crank’ conditions – occur when starting a car in cold conditions, but can now occur in vehicles with start-stop operation.
The ISL78200 is a synchronous buck/pre-boost IC that automatically activates a pre-boost stage when required to maintain output regulation. It integrates a low side MOSFET driver along with a 90 milliohm high side MOSFET. The ISL78200 can accommodate a wide input voltage range of 3 V to 40 V while supplying a regulated 5 V, 2.5 A output at 85 degrees C without heat sinking. The combination of input voltage pre-boosting and step-down regulation with a low 180 uA quiescent current makes the ISL78200 ideal for a wide range of automotive power applications.
Also available now from Intersil is the ISL78205, a similar regulator that does not provide pre-boost capabilities. Like the ISL78200, it is designed for full 2.5 A output at 85 °C, and can be used for general purpose power regulation and 24 V bus power applications.
More information about the ISL78200 and ISL78205 step-down regulators at www.intersil.com/products/deviceinfo.asp?pn=ISL78200