Post Go back to editing

HMCAD1511/1520 input protection

Hi all,

HMCAD1511/1520 input should be in the range 0V-2V, with an absolute rating -0.3V-2-3V according to datasheet.

Is there any clamping achieved in chip, or should we implement it with discrete components? If so, do you have any advises schematic for it?

I haven't found any information related to this in the datasheet.

Best regards

  • Hi,

    Each Analog input is designed to accommodate an analog full scale swing of 1.0Vp-p around a fixed common mode voltage of 0.9V, or essentially a swing on each input between 0.4V to 1.4V. When both Ains are driven differentially this establishes the 2.0Vp-p "differential" Fullscale Input range.

    As noted in the AMR Table 1, the Abs max voltage rating for the Analog Inputs with respect to AVSS(Analog GND) are -0.3V to +2.3V. These AMR voltage levels are nearly a volt beyond the normal Ain operating levels of 0.4V to 1.4V.

    There are no inherent overvoltage protection circuits inside the Analog Inputs so the user must control the level of their Analog Input signal externally.

    Best Regards,


  • Thanks TonyM for this clear and detailed explanation.

    Would you have any advice about the way we should implement such protection?

    We have the ADC input driven by a LT6600 driver, powered with +/-5V.

    We would like to be sure that the protection does not affect visibly our analog signal.

    Best regards

  • Probably the easiest away to protect the input of the ADC would be to use protection diodes on the inputs tied to some clamp voltage.  They shouldn't distort the signals if they aren't conducting.