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Original question:

TPS4H160-Q1: purpose of DIAG_EN

TPS4H160-Q1: DIAG_EN explanation clarification

Craig Hollabaugh1
Prodigy 30 points
Part Number: TPS4H160-Q1

Hello,

I'm considering the A version, TPS4H160AQPWPRQ1, I find the following datasheet, TPS4H160-Q1 DECEMBER 2019 SLVSCV8D, statement about DIAG_EN confusing.

8.3.5.1 Diagnostic Enable Function ... If multiple devices are used, but the ADC resource is limited in the microcontroller, the MCU can use GPIOs to set DIAG_EN high to enable the diagnostics of one device while disabling the diagnostics of the other devices by setting DIAG_EN low. 

1. This sentence says DIAG_EN high and low at the same time. This makes no sense to me. Does this even apply to version A?

Section 8.3.5.1 doesn't apply to version A, but the table mentions if DIAG_EN L and INx L then Diagnostics disabled, no protection. Then 8.3.5.2 fault table show pin behavior if DIAG_EN is enabled (which is DIAG_EN high), the !STx is L in fault condition. DIAG_EN is pulled low via internal resistor, so diagnostics are disabled by default. What does diagnostics disabled actually mean?

2. I've read and re-read DIAG_EN sections trying to figure out how and what the version A DIAG_EN does. Is there an old copy of the datasheet for the just the A part?

Thanks,
Craig

  • 0
    TI__Mastermind 34935 points

    Hello Craig,

    Welcome to E2E!

    In this scenario you have multiple TPS4H160s connected to a single MCU. The MCU might be limited with ADC channels or analog pins, however still want to be able to sense the current on all attached TPS4H160s. What the sentence is simply saying is that you can multiplex the input of the ADC/analog pin and simply disable the current sense being enabled by asserting the DIAG_EN pin low (and making the sense pin high impedance) on the MCU you do not want to measure. 

    Version A does not have current sense capabilities- only an open drain digital output that gives a binary representation of if there is a fault or not. Instead it has four active low ST pins that enable the controlling MCU to interrupt in case of a detected fault on the TPS4H160 (ie current limit, open load, etc.) "Table 2. Fault Table" does a good job explaining the various fault conditions and the ST behaviors. In the A version having the DIAG_EN asserted low would simply put the ST pins into high impedance. 

  • 0 in reply to Timothy Logan
    Prodigy 30 points

    Timothy,

    Thanks for answering my question so early on a Monday morning. Version A are default (with DIAG_EN internally pulled low), diagnostics are disabled. DIAG_EN pulled high, enables diagnostics and turns STx into open-drain fault signals. Is this correct?

    Thanks,
    Craig
    ps. now I understand the 8.3.5.1 paragraph and your above statement. 'Multiple devices' implies several TPS4H160 ICs not multiple devices powered from a single TPS4H160.  

  • 0 in reply to Craig Hollabaugh1
    TI__Mastermind 34935 points

    Craig,

    That is correct.

  • 0 in reply to Timothy Logan
    Prodigy 30 points

    Perfect, thanks for the assist! Have a great day.