2023-03-30, 02:42 PM
(2023-03-30, 01:50 PM)Jean-Marc Douroux Wrote: Hello,
Pay attention to the voltage of the TVS diode protecting the 12V input (D201 in the diagram above). A 15V diode is too tight and risks shorting knowing that alternators can charge from 14.2 to 14.6V and that some LiFeYPO4 batteries could be charged at more than 15V according to their manufacturer's specification for increase their lifespan, which is confirmed by the endurance tests of these batteries. There is no risk in raising the threshold voltage of the TVS between 17 and 20V.
Depends. The switcher used has a max. operating voltage of 18 V and absolute max. voltage of 20 V. So you have
to find the right TVS breakdown voltage between max. charging voltage and max. input of your pmic.
The TVS diode breakdown voltage is 16.7 V minimum. I have connected my lab power supply to give you numbers.
The current rises at 17.7 V. At 18.5 V the current is 50 mA. Beyond this voltage the current rises dramatically and the
polyfuse will break down.
But you are right, if someone is using a non-standard battery he has to check the voltage range of all devices.
Best regards
Chris