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MAX3243: V+ connect to VCC or GND impact

Ann_Lien
Genius 14380 points
Part Number: MAX3243

Hello expert,

Based on datasheet page 13, V+ connection could be connected to VCC or GND. My customer would like to know the impact on signal when V+ is connected to GND and VCC. Below post shows the VCC impact but we don't find any post to mention the impact on signal when we connect V+ to GND. And there is no charge pump block diagram inside MAX3243. Could you please help to answer it? Thanks a lot!

Best regards,

Ann Lien

  • 0
    Guru 316510 points

    On the one hand, V+ is higher than VCC, so when C3 is connected to GND, you need a capacitor with a higher voltage rating (or, for small ceramic ones, the DC bias effects are worse). On the other hand, it might be easier to get a low-impedance connection to the ground (plane) than to VCC.

    The datasheet allows both because it does not really make a large difference.

  • 0
    TI__Guru 52062 points

    Hi Ann,

    To clarify the V+ connection can be through capacitor C3 to VCC or GND - not V+ directly to VCC or GND. 

    With that being said - Clemens explanation is correct there are some small tradeoffs between low impedance connections and voltage ratings of the capacitors themselves but the overall operation of the device doesn't really change all that much either way.

    Best,

    Parker Dodson