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TPS1HB08-Q1: Parallel conection SNS-pin TPS2HBXX

Ilya Bychkov
Prodigy 10 points
Part Number: TPS1HB08-Q1
Hi!
The datasheet for this IC says, that the user can connect the SNS-pin parallel to several TPS2HBXX, all SNS stay on Hi-Z remain until the one of them is selected. But, for example, the error occurs in the control microcontroller and simultaneosly two or more SNS-pin switch to active mode. Could this circumstances damage TPS2HBXX ?
Great Thanks!
  • 0
    TI__Mastermind 32650 points

    Hi Ilya,

    By SNS resistor sharing, there is a phase separated PWM signal that is turning on the DIAG_EN pin for the specific devices. Please refer to figure 40 in the datasheet for more information. There should be no instance in which two devices have their diagnostics enabled at the same time unless as you say, there is a failure in the MCU.

    Both pins are output pins and so there should be no input forced into these pins. It may be possible that the SNS currents from both devices combine and flow through the resistor. This could lead to a high voltage on the SNS pin but the abs max is 18V. If fed into a MCU, this will certainly damage a 3.3V or 5V MCU.

    This situation must be mitigated against to protect the controller from damage. 

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    Prodigy 10 points

    Hi, Shreyas!
    Thanks for fast answer! I undertand, that voltage on SNS may be reach VBB, if occurs current overload or short circuit switching load, or many SNS source connection to the resistor for measuring. I include protect circuit to the ADC input for that situation. I afraid only for TPS2HXX. Did I understand you right, if situation multi-SNS sourcing for the resistor occurs only in failure MCU (very rary and short time, for example, one time for day and one second duration) it will not to damage or shorting live time TPS2HXX?

  • 0 in reply to Ilya Bychkov
    TI__Mastermind 32650 points

    Hi Ilya,

    If the controller is set up right, there should be no situation where both devices output a SNS current through the resistor. If more than one device outputs the current then the amount of current flowing out of a device may be affected and the accuracy will be affected. 

    We do not expect any damage to the device unless the voltage on the pin is over the abs max rating or unless high current is forced into the device.

    Thanks,

    Shreyas