Synchronous buck regulators deliver PoL conversions

13th April 2016

Nat Bowers

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Intersil has announced a family of monolithic synchronous buck regulators that step-down 5 and 3.3V primary rails to PoL inputs as low as 0.6V for GPUs, FPGAs, DSPs and SOCs. The highly efficient ISL78233, ISL78234 and ISL78235 deliver 3, 4 and 5A, respectively, of continuous output current to infotainment head units and 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 ISL7823x synchronous step-down DC/DC converters use a current mode control architecture to deliver fast transient response and excellent loop stability. They integrate low RDSon high-side PMOS and low-side NMOS MOSFETs to reduce external component count and power losses while offering 100% duty cycle operation. The devices combine a switching frequency of 2MHz (default, adjustable from 500kHz to 4MHz) with guaranteed 100ns minimum on time to avoid AM radio channel interference and allow designers to use lower value inductors and smaller capacitors.

The ISL7823x family’s guaranteed minimum on time provides the wide step-down ratio necessary to deliver a 1V PoL supply at high switching frequencies. Competing 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 EMI requirements, which leads to costly redesigns and further testing.

The ISL7823x regulators provide 1% reference accuracy for tight regulation and internal 1ms soft-start or adjustable external soft-start. AEC-Q100 qualified for operation from -40 to +125°C, the converters offer fault protections including over-temperature, over-current, output over-and under-voltage, input under-voltage lockout, short-circuit and negative over-current.

Philip Chesley, Senior Vice President, Precision Products, Intersil, commented: “The pin-compatible ISL7823x family provides automotive customers a reliable PoL solution to manage different stuffing options with the same PCB layout for their entire new vehicle line up. 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.”

The ISL78235 can be combined with the ISL78233 3A synchronous buck regulator, ISL78234 4A synchronous buck regulator, ISL78113A synchronous boost converter, ISL78201 40V/2.5A regulator, ISL78206 40V/2.5A synchronous buck controller and ISL78302 dual LDO to provide a complete off-battery to PoL power supply for an automotive infotainment head unit.

The ISL78235 is supplied in a 5x5mm 16-lead wettable flank QFN package which enables optical inspection of solder joints to lower manufacturing costs. A 3x3mm TQFN package is also available. The regulators are available now, priced at $2.75 in 1,000 unit quantities. The ISL78235EVAL2Z evaluation boards can be purchased for $67.80 each.

The ISL78233 3A and ISL78234 4A synchronous buck regulators are available now in 5x5mm 16-lead wettable flank QFN packages. A 3x3mm TQFN package is also available. The ISL78233 and ISL78234 are priced at $1.75 and $1.95 each in 1,000 unit quantities. The ISL78233EVAL2Z and ISL78234EVAL2Z evaluation boards can be purchased for $56 each.