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TPS27S100: Looking for a part with fault reporting but no wire-break detection

Darren (FAE)
Expert 5483 points
Part Number: TPS27S100
Other Parts Discussed in Thread: TPS274160, , TPS272C45, TPS1H000-Q1

I'm looking for a part that can handle the following conditions without wire-break fault reporting.
Even parts that only do wire-break (open-load) fault-reporting when device is disabled are still a no-go.

Vin = 24V-typical
Iout = 200mA / Ch
Channels = 3Ch (single, dual, or quad-channel devices are ok)
OCP = Current limiting, short-to-GND protection, etc
Mode = Pin Mode (No SPI / I2C / etc - we need pin-mode control)

Do we have anything to meet the above requirements?

I'm curious if a device with DIAG_EN pin could meet these requirements.
If it has wire-break detection, but there is no fault reporting when device is enabled, then DIAG_EN could track the EN pin, etc.
That would provide fault reporting w/o wire-break during normal operation, and when device is disabled all fault reporting is disabled.

  • 0
    TI__Mastermind 32650 points

    Hi Darren,

    I would recommend looking at TPS274160. This is a 40V(max), 4-ch 160mOhm high side switch with GPIO control. It has a diag_en pin and a current sense output with configurable current limit and short to GND protection.

    When DIAG_EN is disabled, all protections are present but there is no output to the SNS or FAULT pins.

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    TI__Expert 5483 points

    Hi Shreyas,

    There are some requirements that are difficult to consolidate. 

    Does TPS27S100 report any faults to xFLT pin when diag_en = low? Will the device report wire-break / open-load faults when diag_en and en are both high? I know there was a device that only outputs the open-load fault if the channel is disabled…

    could you give me a list of all 24V devices that still report OC / TS faults to a fault pin, even with diag_en low? (I think TPS272C45 fits that criteria)

  • 0 in reply to Darren (FAE)
    TI__Mastermind 32650 points

    Hi Darren,

    Please refer to the fault handling table in the datasheet.

    When Diag_en is low, no device reports OC or short to gnd faults to the fault pin as the diagnostics are disabled.

    I think you are confusing the Version B of TPS27S100 as these devices only do open load detection when the channel is off while open load when the channel on is based off the SNS output and is up to the user. Still, this only works if Diag_en is high.

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    TI__Expert 5483 points

    Hi Shreyas,

    Understood.

    in that case, can I get a list of devices that won’t report open load with the channel and diagnostics enabled?

    tps274160 seems to be a good example. On the other hand tps1h000-q1 seems to report open-load even with channel enabled. So I know some parts do one or the other.

    if I could have a list to look through it would be great. Not easy to search that feature with the online tool.

  • 0 in reply to Darren (FAE)
    TI__Mastermind 32650 points

    Hi Darren,

    You are correct that TPS1H000 does this. Another device that does this is TPS1H200. 

    But even for these devices, if DIAG_EN is pulled low, no reporting is performed to the FLT pin. 

    Unfortunately, a list is not helpful because this is the entire portfolio of devices for integrated switches: https://www.ti.com/power-management/power-switches/high-side-switches/products.html#p1694=High-side%20switches

    Perhaps it will be better to select based on the fact that it seems that this is an industrial application and therefore we offer these four devices: https://www.ti.com/power-management/power-switches/high-side-switches/products.html#p1694=High-side%20switches&p1498=Catalog 

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    TI__Expert 5483 points

    Hi Shreyas,

    I think I'm starting to get the hang of it.
    I'm looking at TPS274160 as it does not have open-load detection while the channel is enabled, correct?

    It also says in the comments below "Table 8-2. Fault Table"

    An external pullup is required for open-load detection.

    Regarding this comment, does it mean if no external pullup is used, that open-load detection will not function? 
    (Thus the xFAULT pin will not go low during an open-load condition)

    If it goes too deep into device behavior (NDA), feel free to reach out to me offline.

    Regards,
    Darren

  • 0 in reply to Darren (FAE)
    TI__Mastermind 32650 points

    Hi Darren,

    TPS274160 does have open load detection in the off state. This is performed with an internal reference voltage that checks to see if the output and the input voltages are close to one another signifying an open load. Since the rail is floating even small leakages internal to the device could pull the output voltage down. Therefore, to avoid this we ask for an external pull up resistor that connects the output to the input. This is a large resistance that has no effect on normal operation but will help with open load detection.

    Please look at section 8.3.6.2 for more information.

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    TI__Expert 5483 points

    Hi Shreyas,

    My wording was a little ambiguous. Let me try and re-organize my thoughts...

    [1]
    For the "A" device, even if DIAG_EN is High, when ENx is High, that channel's open-load detect function is disabled, correct?

    [2]
    As long as (Voutx) < (Vsupply - 2.6V) then the open-load detection will not report a fault, right?
    In order to report a fault, (Voutx) > (Vsupply - 2.6[V]) for > ~560[us] typical, right?

  • +1 in reply to Darren (FAE)
    TI__Mastermind 32650 points

    Hi Darren,

    1. There is no straightforward answer here as it is device dependent. In the case of TPS274160, you are correct as there is no on state open load detection for version A. But TPS27S100A does have a current level based open load detection when ENx is high. The best way to understand if this exists or not for the device is to look at the fault table as you have correctly done so for TPS274160.

    2. You are correct for off state open load detection.

    Thanks,

    Shreyas