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TPS274160: THER pin configuration

Hanno Reimer
Intellectual 1930 points
Part Number: TPS274160

Tool/software:

We are working on a Non-Safety Remote I/O system , for output side we have used Texas TPS274160A. While discussing IC’s THER pins we came across few queries related to correct method of thermal fault clearing .

 

I am putting my doubts below, it would be great if could provide some clarity . 

 

referring to this snip from the datasheet

 

 

 

 

  

Case 1 : When THER pin is permanently connected to low logic  - When fault occurs Auto retry mode it activated. Here Thermal fault gets cleared when Tj <T (sd,rst) OR  after toggling the Enx pin.

 

 

Case 2: When THER pin permanently connected to high logic ,  when fault occurs channel latches off and it will remain off until thermal shutdown fault signal is cleared .

 

1st method to clear fault signal :  Step1 .  Pull THER pin to low logic to start auto retry mode  , Step 2.  Toggle respective ENx pin.

 

2nd Method to clear fault signal : Step 1. Directly toggle respective Enx pin , with its THER pin pulled up.

 

 

Case 3 : Connect THER pin to MCU , with initial status pulled high , under fault condition channel latches off , after some delay pull THER pin low to start auto-retry mode , after this toggle ENx pin to clear fault signal. Once fault signal is cleared again pull THER pin high.

 

Q1. In case 2 , which is the correct method for clearing the fault signal.

 

Q2 . Out of the 3 case , which one is recommended

 

Kindly share your views on how to configure THER pin.

  • 0
    TI__Genius 10395 points

    Hello, 

    Q1. In case 2 , which is the correct method for clearing the fault signal.

     For case 2 the fault signal is determined by the heat of the device. In order to properly clear the fault as stated early "Tj <T (sd,rst)" this condition has to be met. Changing THER pin logic level will not have an impact on cooling the device only turning the channel off. Toggling EN will basically be a pseudo auto retry till the thermal condition is cleared. 

    Q2 . Out of the 3 case , which one is recommended

    Similarly to the point made in the previous response the FLT status will be dependent on the temperature. Turning off the channel with effectively cool the device in a thermal shutdown scenario but when re-enabled it could just heat up and shutdown again. 

    For this configuration, why not just keep THER low to have the auto-retry functionality instead of latching off?

    BR, 

    Alan