High efficiency DC-DC step-down

[wedwo]

I'm looking for an integrated component or basic circuit with high efficiency DC-DC regulator that will allow me to output 19.5v at 3.5 or more amps from a 24v battery.  I could step up from 12v but I assume I'm going to get more efficiency with 24-> 19.5.
What should I be looking at?  I'm a fan of the Tracopower range of converters: https://www.tracopower.com/products/browse-by-category/detail/dc-dc-converters/non-isolated-step-down-regulators/ 
I assume I'm not going to get away with a neat drop-in gadget like that, particularly at 3A+ output.
Any pointers would be appreciated....
Oh, I'm basically wanting to power my laptop (PSU is 19.5v 3.3a) for extended periods (4 hours) more efficiently than with an inverter based solution.
Thanks!

[digsys]

I have just completed a DIN module to run from PoE > laptop / LCD voltages and other devices with my new favourite DC-DC module - I3A-4W0-05A-150V/001-R (also supplied as T31SN24005). A bit pricey maybe but 9.0 - 53V ip, 5.0 - 30V op, 4.5A at up to 98% efficiencies !! An awesome part.
For that current, the only other high-efficiency series I've used are the Vicor series. I also use Tracopower, nice divices. Would you maybe run them in parallel?

[wedwo]

Great response, thanks digisys!  I don't know about running the tracopower in parallel... I'm needing 19.5v 3a output so it may be tricky.
I'll check out those components you posted.  Cheers!

[digsys]

Forgot to mention -
One of my favourite brands is Power-Trends - used several 1,000 over the years, and still do. Before I used the modules I listed, I ran with - PTN78060 H and PT6304 N. Both are 15 - 36Vin and 12 - 22Vop for the PTN78060, and 2.5 - 22Vop for the PT6304 at 3.0A. The PT6304 is "obsoleted", but can still be found. I think I may have a few old stock.
Also, a "cheap" trick I (and others) often use, for increasing Iop, I recently explained in the "LT3081 Parallel Different Sources" thread. gl

[mariush]

If you're talking about lead acid batteries, keep in mind that those will be as low as around 10.8v when discharged, and they'll probably "float" at around 14v when charging, so you're looking at around 28v maximum voltage.

Here's some options :

33$ : https://www.digikey.com/product-detail/en/tdk-lambda-americas-inc/I6A24014A033V-001-R/285-2434-ND/5481911

Up to 40v input,  up to 24v output (configurable with a resistor between two pins), up to 250 watts , up to 14A, up to 98% efficient.

The datasheet tells you how to choose the resistor value to output a specific voltage you need (for example 750 ohm for 18v, probably around 650 ohm for 19.5v)  and it also tells you if you have to connect a pin to ground or to input voltage to turn on the regulator (depends on exact model).
Besides that, you'd probably only need an input and output capacitor to add and your cable with barrel jack.

22$ : https://www.digikey.com/product-detail/en/tdk-lambda-americas-inc/I3A4W005A150V-001-R/285-2719-ND/7321112

Same as above, but maximum 135 watts ... up to 30v output voltage, up to 4.5A

[ocset]

One of these?
https://www.analog.com/media/en/technical-documentation/data-sheets/8610abfa.pdf

what is your vin(min)?

Thers more...
https://www.analog.com/en/parametricsearch/11472#/p5362=Buck&p5573=min|23&p5574=25|max&p5347=min|19&p5357=19|max&p5349=3|4.5&qsfv=vinmin|23_vinmax|25_vout|19_iout|3