Buck converter simplifies point of load supply designs

Paul Boughton

Intersil has developed a synchronous buck controller that can generate the point of load (POL) voltage rails and bias voltage rails for a wide variety of applications in industrial and general purpose segments, writes Nick Flaherty.

The wide input and output voltage ranges make it suitable for telecommunication and after-market automotive applications.

The ISL8117 uses the valley current modulation technique to bring simplified power supply design with minimal number of components and complete protection from unwanted events.

“We have a family of products that target battery powered operation where we have optimised the design for lower shutdown current,” said Mark Downing, senior vice president of corporate strategy and infrastructure power products at Intersil. “The other things that we have tried to do is simplify the overall design task for the customer and one area is on the device selection,” he said. “With the wide Vin and Vout it means the device can be used in multiple different applications from a few amps to 20A with different FETs and the ability to do 48V to 12V conversion or 48 to 1V at a few amps – the versatility is very appealing.”

Intersil has also minimised the pin count with the default design settings to 16 pins to minimise noise from traces that are slewing large amounts of energy in an industrial environment.

The device uses internal loop compensation and single resistor settings for other functions such as operating frequency and overcurrent protection. Its current mode control with VIN feed-forward enables it to cover various applications even with fixed internal compensations. The DEM/Skipping mode at light-load dramatically lowers standby power consumption with consistent output ripple over different load levels.

The ISL8117 offers programmable soft-start and enable functions along with a power-good indicator for ease of supply rail sequencing and other housekeeping requirements.

In ideal situations, a complete power supply circuit can be designed with 10 external components and provide OV/OC/OT protections in a space conscious 16 Ld 4mmx4mm QFN or easy to assemble 6.4mmx5mm 16 HTSSOP package. Both packages use an EPAD to improve thermal dissipation and noise immunity. Low pin count, less number of external components and default internal values, makes the ISL8117 suited to simple power supply designs.