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TVS1400: Forward Voltage vs Forward Current

Part Number: TVS1400
Other Parts Discussed in Thread: TPS24750, TEST

Hi All,

I am checking TVS1400 as a replacement to SMAJ12A-E3/5A. This TVS is placed after TPS24750 + CSD16570Q5BT reverse current blocking FET. TPS24750 does not allow below -0.3V at its output. The CSD16570Q5BT has ~0.6V body diode drop. Therefore at my connector pin, I want to prevent voltages lower than -0.9V. In case of a fuse tripping, the cable inductance will turn on my TVS in the forward mode. I expect worst case 3A. 

I want to find out the forward voltage drop of TVS1400 @3A, the forward conduction behavior is not given in the datasheet. I simulated it on Tina TI, however I see an interesting behavior where the forward drop jumps from 1.3V to 2V at 1.5A forward current and reaches 2.2V @3A. Is the Tina Spice model of this component modelling forward conduction behavior correctly (doesn't look like a simple diode at all)? How much drop would I see @3A free-wheeling situation?

Kind regards,

Zeki

  • Hi Zeki,

    Welcome to E2E!

    I will have to get back to you on the behavior of the model. Would you be able to share the TINA schematic you are working with?

    The forward voltage of the TVS1400 was only tested in the conditions mentioned in the datasheet. The forward voltage drop of the device should remain constant to the values listed in the datasheet.

    Best regards,

    Andy Robles

  • Hi Andy,

    Thank you for your quick reply! I've attached the simulation file.

    TVS1400 DC transfer analysis file: TVS1400_DC.TSC

    Kind regards,

    Zeki

  • Hi Zeki,

    The TVS1400 in general cannot support 3A of DC forward current, and the TINA model cannot model transients. There isn't really a good way to model ESD transient response of the device because of the variation from an actual board to a model.

    For the forward voltage we do not have test measurements to show the characteristics besides what is in the datasheet. The forward clamp voltage spec in the datasheet of 2V typical was measured at 43A. This means that at 3A we expect the clamp voltage to be much lower.

    Best regards,

    Andy Robles

  • Hi Andy,

    My intended operation is not 3A DC, but a 3A peak inductive freewheeling pulse with linear decrease of amplitude. So it'd be much slower than an ESD event, that's why I tried to simulate it with DC transfer analysis.

    Then I understand that the TINA model of TVS1400 is not intended for such analyses. I saw the 2V typical but it also says 5V maximum, and 5V is too much for my application. So I will stay with the SMA diode to be safe.

    Thank you for assisting me!

    Zeki