Connecting Foccci

[mitch]

I bought a Foccci last year or maybe even longer ago but tried to configure it. But I run into a problem, my fuse was burned. I checked my wiring but it seems ok, when I replace the fuse and do not connect Foccci the fuse stays intact. So I decided to try foccci only on a seperate 12v battery. Hooked up the 12v, added 3 gnd wires, I only left pin 12 out (i know only one would be enough but just to be sure) measured for resistance between the grounds (0,0 Ohm) and between the 12v and ground 78.6 kOhm. But also with only 4 wires attached the fuse would burn.
When I look closely I see component U5 (which I believe is component SMAJ16A-TR) is cracked. I have a version 5 btw. Can anyone tell me what I did wrong so when I replace U5 this will not happen again or is it trail and error? Could this be because I have a small truck which uses 24v as the onboard system I overloaded and simply should put 12v on it (although I read anything between 12-24v is ok (but the dc-dc deliveres 27v)?

Hope it's the latter and when I replace the U5 and get 12v to Foccci I can continue.

Thanks Michiel

[uhi22]

Hi, sorry to hear this.
Seems we have some inconsistent information about the intended supply voltage range.
The protector diode (U5, TVS, SMAJ16A) is designed for operating voltages up to 16V, will start current draw between 18V and 20V. Data sheet: https://www.littelfuse.com/assetdocs/tv ... 44670AED9D

This means, the Foccci is NOT designed to work on nominal 24V systems.

If you are lucky and nothing else was destroyed by the 24V, you could de-solder the TVS, and check with a bench power supply what happens. Use current limitation to 200mA, and slowly rise the voltage from zero to 7V. Measure the 5V rail. If the 5V is fine, further slowly raise the supply voltage to 16V, and continuously observe the 5V line.

Edit: In the wiki https://openinverter.org/wiki/Foccci indeed we wrote "9 to 24V are fine". This is wrong. Nominal 16V is the official range, limited by the TVS. Just updated this to 9 to 16V.