Automotive DC/DC converters step-down 5V rails to point-of-load

April 12, 2016 // By Graham Prophet
Intersil’s synchronous buck regulators deliver POL conversions for infotainment and advanced driver assistance systems; a family of monolithic synchronous buck regulators step-down 5V and 3.3V primary rails to point-of-load (POL) inputs as low as 0.6V for GPUs, FPGAs, DSPs and SOCs.

ISL78233, ISL78234 and ISL78235 deliver 3A, 4A and 5A, respectively, of continuous output current to infotainment head units and advanced driver assistance systems (ADAS) employing forward-looking smart cameras to detect and classify objects. The pin-compatible sync buck regulators allow system designers to make a simple BOM change and drop in the right device to their PCB to address the varying load requirements of entry-level to luxury car models.


The converters use a current mode control architecture to deliver fast transient response and loop stability. They integrate low R DSon high-side PMOS and low-side NMOS MOSFETs to reduce external component count and power losses while offering 100% duty cycle operation. The ISL7823x combine a switching frequency of 2 MHz with guaranteed 100nsec (max) minimum on time to avoid AM radio channel interference and allow designers to use lower value inductors and smaller capacitors. The family’s guaranteed minimum on time provides the wide step-down ratio necessary to deliver a 1V POL supply at high switching frequencies. Intersil asserts that other solutions often do not guarantee the low duty cycle needed to deliver very low outputs to the applications processor at switching frequencies above the AM band. This increases the risk of failing the system designer’s electromagnetic interference (EMI) requirements, which leads to redesigns and further testing. “The pin-compatible ISL7823x family provides automotive customers a reliable point-of-load solution to manage different stuffing options with the same PCB layout for their entire new vehicle line up,” said Philip Chesley, senior vice president of Precision Products at Intersil. “Our sync buck regulators address the load requirements of single-, dual- and quad-core processors in a single footprint, allowing carmakers to easily differentiate models.”


Features and specifications include;


- Input voltage range from 2.7V to 5.5V efficiency up to 95%

- 100nsec guaranteed phase minimum on time for wide output regulation

- Adjustable switching frequency from 500 kHz to 4 MHz, with 2 MHz