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INA260: VBUS pin blowing up on chips

Dan Stevens
Prodigy 10 points
Part Number: INA260

Tool/software:

Hello, 

We have a fairly simple circuit for monitoring 3 dc voltages with 3 INA260's and a raspberry RP2040 microcontroller.

The dc voltages are 24v batteries. The INA is powered using a 2405 TracoPower regulator, the RP2040 has is own 3.3v regulator, all share the same ground.

Our issue is we keep blowing holes in the INA260 chips and we can't work out why. 99% sure its on the VBUS pin as this pin discolours sometimes.

The IN+ and IN- pins are left floating.

The damage is always in the same place.

We have another system using an ATMEL328P with a voltage divider and 5.1v zender diode connected direct to an analogue pin messuring the same circuits with no issues. The INA260 is new to us and we're hoping to use it in many more projects but so far we can't get it right.

Any pointers would be great.

Thanks.

  • 0
    TI__Mastermind 19295 points

    Dan, 

    Thanks for using E2E! I have a few potential ideas to run down that could be causing issues here:

    - Is it possible to see more of the schematic here, ie, any additional components attached to the device for its operation?

    - What amount of current are you attempting to measure with the device? Is this damage occurring rapidly during power on, or is this more of an elongated exposure type of damage? Is the load line inductive in any way?

    - Have you looked at the overshoot on the 2405, and also on turnoff conditions of the VBus line? If these voltages are ringing in any way, kickback could be ringing the voltage beneath the absolute max of the device, which is -0.3V (and 6V for the overshoot of the Vs pin):

  • 0 in reply to Carolus Andrews
    Prodigy 10 points

    Hello, thanks for your reply. Im not sure how much more information I can share on an open forum.

    The 2405 is powered from any of the 3 voltage inputs via 4001 diodes. So the INA260 is always powered on the 5V side when voltage is present on the VBUS. The 2405 also powers other IC's; MAX485, PCA9685PW. The VBUS pins is connected direct to the DC bus bars.

    We are not measuring current with the INA, the IN pins are floating.

    The fault seems to occur randomly and we do not know when or how. 

  • 0 in reply to Dan Stevens
    TI__Mastermind 19295 points

    Dan, 

    Understood. I will send you a friend request if you would prefer and keep sensitive information off of the forum. On the current measurement, we typically recommend that the inputs be shorted to GND if not measuring current. I would recommend grabbing a scope shot of the VBUS waveform during turn on and turn off, as well as any other possible load conditions you may be toggling in the system, and share those with me if you could.