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REF1112: Layout nearly surge and noise factor

Guru 19565 points
Part Number: REF1112

One customer is considering to use REF1112 or LT1004. (First priority is REF1112)

But layout is possibility to occur surge and noise.

Can these reference use nearly surge and noise layout?

If there required external circuit for measure, please let me know.

※Example layout: C~L voltage is 24V.

Best regards,

Satoshi

  • Hi Satoshi,

    The REF1112 can work in a noisy environment. Noise and surges can be mitigated by the use of bypass capacitors to handle the transient responses. Make sure to have capacitors to mitigate the noise. This can be done by having a large 1uF cap and a 0.1uF cap in parallel. Murata has a good app note for this.

  • Hi Marcoo

    Thank you for kind reply,

    Sorry for additional question, can above layout (with parallel 1μF capacitor) also use the case of occur overvoltage and overcurrent?

    I concerned with sudden large voltage and current over the variable resistor (47V) and zener (36V). 

    Best regards,

    Satoshi

  • Hi Satoshi,

    It depends how long the surge is.

    What is the typical expected  voltage on the bus line? What is the maximum surge voltage expected?

  • Hi Marcoo

    I apologize for misinformation,

    One customer request is updated, true required spec is surge voltage about IEC61000-4-5 Level-4, for 4kV ±10% voltage.

    I update schematic is attached below. If there any careful points, please let me know.

    Best regards,

    Satoshi

  • Hi Satoshi,

    I would add 0.1uF ceramic capacitors in the areas that are sensitive to ESD.

    I would also a 0.1-μF load capacitor is recommended to maintain stability under varying load conditions for the REF1112 so make sure to add one.