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DS26LV31T: Field Failures of DS26LV31/32 Devices

Michael Schreiber2
Prodigy 10 points
Part Number: DS26LV31T
Other Parts Discussed in Thread: AM26LV31E

We have been experiencing a number of device failures on DS26LV31 Drivers, and some DS26LV32 Receivers. When the drivers fail we notice a shorting condition to ground (or less than 5 Ohms) on one of the drivers output pairs. The circuit runs a 1 M-bit serial link between 2 different assemblies a few meters apart. The boxes are powered from 2 different DC power supplies with a common ground reference between the boxes.

The link does not have any other external protection devices (clamping diodes, Transorbs, etc). Is there a recommended configuration for external protection (I saw some recommendations on previous posts to the forum on this device)?

Are there common failure modes, or other susceptibilities to the devices (ESD, Transients, etc) especially when it appears the driver outputs are damaged?

I noticed there are also AM26LV31E series devices which have a higher ESD rating than the DS series devices. Does TI maintain any failure rates for the AM vs the DS series parts?

A schematic of the circuit can be provided.

  • 0
    TI__Guru 53555 points

    Hi Michael,

    ESD and Transients are common causes for driver and/or receiver damage when operating in a noisy environment. Example sources can be coupled transients from nearby switching power rails or ESD from attaching cabling. As these devices have relatively low ESD ratings, this would be likely cause. I am not sure about the failure rates between the AM and DS series, but AM26LV31E would provide better ESD protection based on it's test rating. 

    It is recommended that some peripheral ESD and transient protection also be implemented on the board to protect the device. Common methods include Transient Voltage Suppression (TVS) diodes, Common-Mode Chokes, and small series resistances along the signal path (pulse proof resistors are best). Protection schemes for RS422 can be very similar to those of RS485. This application Report elaborates on the topic: Protecting RS-485 Interfaces Against Lethal Electrical Transients

    If you have other concerns about the schematic, I would be happy to look them over and point out other potential causes for damage. If you wish to share them offline, let me know and I will contact you directly. 

    Regards,

    Eric