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THS4151: Request to confirm simulation results and VICM

Shinichi Inoue
Guru 20876 points
Part Number: THS4151
Other Parts Discussed in Thread: THS4551, THS4505

Tool/software:

Dear Specialists,

My customer is considering THS4151 and has a confirmation request.

I would be grateful if you could advise.

---

When ±2V is input to VIN_P and VIN_N is fixed at 0V
Input resistance is 1kohm and the feedback resistance is 500ohm.
VOCM = 1.5V,

the output voltage will be as follows.

VOUT_P = 2V＠VIN_P＝2V
＝1V＠VIN_P＝-2V
VOUT_N = 1V＠VIN_P＝2V
＝2V＠VIN_P＝-2V

A negative voltage is input to VIN_P, but the voltage VP applied directly to the + terminal
will be 0.67V~1.33V.

VN is the same voltage, 0.67~1.33V.

TINA TI simulation went well.

On the other hand, 

The common mode input voltage range of the THS4151 is (Vs-) +1.5V to (Vs+) -1.5V.

When used with a single +5V power supply, it becomes 1.5V to 3.5V.

Does this mean that it cannot be used because it is outside the input voltage range?

THS4151 Application Circuit.TSC

ｰｰｰ

I appreciate your great help in advance.

Best regards,

Shinichi

  • +1
    TI__Mastermind 26375 points

    Hello Shinichi,

      Thank you for all the details and schematic. Your analysis is correct. It seems like this model is not functioning correctly at single supply of 5V; since, it should have not have been giving you the correct output.

      From the datasheet, output common-mode voltage is shown on Figure 24, rather than our newer devices which would have listed it as a specification. For this device, Vocm with singly supply of 5V is limited to around 0.5V to 2V. This is in range, but it seems like input-common mode voltage will be violated. 

      Would it be possible to switch over to another device such as the THS4551. The THS4551 has the same bandwidth, Negative Rail Input, and Rail-to-Rail output. It can work with single supply of 5V, and has very low noise and distortion. The THS4551 has lower offset voltage, but its only specification that is lower than THS4151 is slew rate. 

    THS4551 Application Circuit.TSC

    Thank you,

    Sima

  • 0 in reply to Sima Jalaleddine
    Guru 20876 points

    Hi Sima,

    Thank you for your reply.

    I understand.

    As expected, the input voltage (0.67~1.33V) does not satisfy the VICM (1.5V~3.5V @ Vcc5V) of THS4505.

    Therefore, the operation is not guaranteed.

    I'll share this information and consider THS4551 as an alternative.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • +1 in reply to Shinichi Inoue
    TI__Mastermind 26375 points

    Hello Shinichi,

      Yes, that is correct. Feel free to reopen the thread if customer has further questions or concerns.

    Thank you,

    Sima 

  • 0 in reply to Sima Jalaleddine
    Guru 20876 points

    Hi Sima,

    Thank you for your reply.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi