Good Morning/Afternoon.
Thanks for your time.
I must use 2 ISO808TR in a project.
Because of the large current requested (0.5 A * 8 *2 = 8 A or worse 0.7A *8 *2 = 11.2A) and the absence of heat dissipator (orange derating curve) I could not use a diode as reverse voltage protection.
Because of lack of time I could not use (because I could not test before the final product) a solution control + MOS based like LM5050-1 or similar.
So I need to ask about reverse protection of ISO808.
In page 24 (Chapter 😎 of https://www.st.com/resource/en/datasheet/iso808.pdf it is not said if Is of the diode is Icc of Table 4 (from 5.5mA to 16mA). I think that in reverse polarity protection the diode should be off and the only current is the irrilevant reverse current.
From the following note I assume that it is; so I only need a signal diode and not a power diode
"In normal operation (no reverse polarity), there is a voltage drop (ΔV) between GND of the device and GND of
the system. Using option 1, ΔV = Rgnd * Icc. Using option 2, ΔV = VF@(IF)."
My question is with the following values
- VCC = 24 -30 V
- and Rgnd = 10K Ohm (=> 30V*30V/10K = 0.09W; a normal 0805 resistor will work; 30V/10K = 3mA << 25 mA)
- and VSSA310SHM3_A/H (Vrrm =100V) diode (If = 3A >> 16 mA) .
Should I expect any problem?
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2nd question
Are the 0.01uF used in development kit strictly necessary and where should be placed?
Are they forced to be on the same plane (top or bottom) of ISO808?
There is no gerber, only schematics.
Thanks for your time.
Best Regards
