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S12ZVL with external 5V supply

Question asked by Laurent Lamesch on Dec 7, 2016
Latest reply on Dec 9, 2016 by Radek Sestak

Hello,

 

when using the S12ZVL, is it possible to use an external 5V supply instead of the internal one?

In my specific case, the external supply delivers a voltage between 4.85 V and 5.15 V (worst case). It already supplies power to an external circuit.

 

Would it be sufficient to connect VDDX and VDDA to the external 5V supply?

 

The S12ZVL internal voltage regulator should not supply current to the external circuit connected to the external 5V supply (for the case that the internal regulator output voltage is larger than the external one), as the external circuit draws too much current for the S12ZVL internal regulator. The external PNP is not an option because of additional costs.

 

Also, the internal LIN transceiver (physical layer) of the S12ZVL should be used, and therefore I assume that VSUP cannot be connected to the external 5V supply, but must be connected to VBAT instead?

 

One of the reasons for this question is that the S12ZVL ADC input voltage range should exactly match the output voltage range of the external circuit supplied by the external 5V. There are other solutions to this problem, but they have their drawbacks.

 

Thank you and with best regards,

Laurent

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