Automotive buck converters for 48V rails Leave a comment

The components are comparable, however rated at 5 to 100V or 5 to 80Vin, and a pair of.5A or 3.5A out.

There are usually not synchronous rectifier ICs. As a substitute they embody a 500mΩ (950mΩ max) collection swap and anticipate a excessive present Schottky diode to be linked externally.

Half numbers are AP68255Q (8V 2.5A), AP68355Q (80V 3.5A), AP6A255Q (100V 2.5A or AP6A355Q (100V 3.5A).

Management is thru a relentless on-time scheme, with the collection swap turned on each time the output drops beneath its regulation threshold.

“This system leads to quick load/line transient response, simple loop stabilisation, and low output voltage ripple, making the units simpler to include by requiring fewer exterior elements,” claimed Diodes. “On-pulse timing is calculated, inversely proportional to enter voltage and instantly proportional to output voltage, to take care of a pseudo-fixed frequency over the enter voltage vary” – at ~300kHz. Minimal off-time is often 200ns.”

Fixed frequency operation eases EMI filtering as does, it claims, the corporate’s proprietary gate-driver which is meant to “scale back swap node ringing results with out sacrificing the turn-on and turn-off instances of the n-channel mosfet swap”.

Though that is an asynchronous buck, there’s an inner 10Ω mosfet within the synchronous rectifier place (labelled Q2 in diagram left).

What’s that for?

“Q2 is a small low-side FET to assist refresh the bootstrap capacitor voltage within the occasion of lengthy interval no switching,” the corporate informed Electronics Weekly. “This normally will occur in PFM [pulse-frequency modulation] and no load conditions.”

Different options embody an allow pin which might shut the machine down to five.6μA in addition to programme the under-voltage lock0out threshold if two resistors are linked to it.

Over-current safety has frequency fold-back to scale back junction temperature throughout faults, and is backed by over-temperature safety with hysteresis between 160 and 140°C. Nominal working vary is -40 to +125°C.

Qualification is to AEC-Q100 Grade 1, manufacturinng amenities are IATF 16949 licensed and there are supporting PPAP paperwork.

For non-automotive use there are associated industrial-grade components.

For example, discover the 100V 3.5A AP6A355Q on this Diodes web page.

At a lot increased powers, Vicor introduced 48 to 12V automotive DC-DC converters in March