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THP210: Input Common-Mode Range

Bernhard Boehmer
Expert 1050 points
Part Number: THP210

Hello TI,

Figures 41 and 44 in sbos932a seem to define the input common mode in a DC-coupled application as the voltage on the distal side of the RI resistors.

On pg. 5, the datasheet specifies the Input Common-mode voltage range as V_VS– + 1 to V_VS+ – 1.

Fig. 53 on pg. 27 and Fig. 55 on pg. 29 both seem to show applications which do not conform to the above, since V_ICM = V_VS-.

Could you clarify the Input Common-mode voltage specification for this part, please? Are the circuits Fig. 53 and Fig. 55 allowable?

  • 0
    TI__Mastermind 49405 points

    HI Bernhard,

    There are a few clarifications and corrections that need to be made to the datasheet; and the datasheet is in the queue to be corrected.

    The correct definition for VICM refers to the input common-mode voltage right at the input terminals of the THP210 Fully-Differential Amplifier.The specification on pg 5 of the datasheet defines the VICM valid range as (V_VS-) + 1V <VICM < (V_VS+) - 1V; where this is the input common-mode voltage right at the input terminals of the THP210 need to be at least 1-V from both supply rails.

    • Figure 41 needs to be corrected.  It shows a 'VICM' label in the wrong location, on the other side of the input resistor.  This label in the figure needs to be re-named as input signal common-mode voltage, and this common-mode voltage is not the same as the VICM voltage seen by the THP210 input terminals.  .

    • The circuit of Figure 55 of page 29, was tested using a fully-differential input signal as shown below.   The corrected figure should be drawn as follows for Figure 55, showing a fully differential input signal is applied at the inputs.  The common-mode voltage of the fully-differential signal can be between 0V and +5V.

    • The circuit of figure 53 (MFB filter) is performing a single-ended to differential conversion.  It accepts a single-ended signal input signal, and perform the single-ended to differential conversion.  If the THP210 is shown powered with a uni-polar +5V supply, the figure needs to be more specific and define that the input signal is expected to be uni-polar, centered above ground. Alternatively, a bipolar +/-VA THP210 supply can be used accepting a wider common-mode (or a bipolar single-ended input signal).

    I am working with the systems engineers to perform these datasheet corrections and clarifications. 

    Thank you and Regards,

    Luis 

    .