Hi team,
LM5156HEVM-FLY development board itself is the output of 5V, I measured VCC is 6V, I change the resistance of R19, change the output to 12V, I measured VCC is still 6V.
So I don't quite understand what determines the VCC voltage? With what parameters?
Please explain it in detail.
Thank you very much for your help.
Best regards,
Hello,
Thanks for reaching out. The VCC pin is the output of the internal VCC regulator and supply voltage input of the MOSFET driver and it is therefore not affected by the Vout value.
At page 5 of the datasheet in table 8.5 Electrical characteristics (https://www.ti.com/lit/ds/symlink/lm5156h.pdf?ts=1635930645674&ref_url=https%253A%252F%252Fwww.ti.com%252Fsitesearch%252Fdocs%252Funiversalsearch.tsp%253FlangPref%253Den-US%2526searchTerm%253DLM5156H%2526nr%253D39) you can find the typical values for the VCC regulator with Vbias = 8V.
At page 8, figure 8-4 you can find a graph of the VCC behavior, as you can see, VCC is a constant value when Vbias > 6.85V , otherwise it follows the Vbias.
Let me know if I can help you furthermore.
Kind regards,
EM
