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TPS2660: IMON Pin in relevance with output pulse.

Pang
Expert 2385 points
Part Number: TPS2660

Hi Ti,

I am trying to work out on the IMON Pin because I am planning connect to an op-amp to provide  feedback to MCU to show different status during for different error fault detected.  Fewquestions related to the below table that we had use scope to check during the Vin is 12V with several fault condition reverse polarity, over current at >1A, short circuit.

 

Vin

Test Condition

Output Pin

Output / Imon Pin

Output / Imon Pin

Imon

12V

Power Reverse Direction

Pulse voltage range is 2.05V
Pulse current range is 0A

Cycle time: 520ms

Pulse width: 4.4ms

Pulse voltage range is 1.5V

12V

Over Current 1A

Pulse voltage range is 5.15V
Pulse current range is 1.025A

Cycle time is 520ms

Pulse width: 4.4ms

Pulse voltage range is 1.5V

12V

Short Circuit

Pulse voltage range is 183mV
Pulse current range is 0A

Cycle time is 520ms

Pulse width: 4.4ms

Pulse voltage range is 1.5V

1) It is the cycle time and pulse width time a default and consistent from the IMon pin?

2) When the protection circuit is active, the TPS2660 can auto cut down the power. Then what is the function for the IC SHDN pin?

3) Based on the data measured above, from the Imon pin can we know the specific fault condition?

Thanks.

  • 0
    TI__Genius 16305 points

    Hi,

    Please note:

    In case of reverse input polarity fault, an external 100-kΩ resistor is recommended between IMON pin and opamp input to limit the current through the ESD protection structures of the opamp.

    Ans to Question 1:

    IMON pin will follow the load current behaviour under different fault conditions except for input reverse polarity fault.

    Looking at the table, I gues TPS2660 is configured to opertare in circuit breaker mode with auto-retry, is this correct?

    If that is true, then device will have consistent behaviour as observed during Over curent 1A test and short circuit test.

    Please refer to Figure 41 and Figure 39  on page 22 of TPS2660 datasheet for the IMON and Output behaviour during a over current fault.

    Ans to Question 2:

    SHDNb pin is to enter a low current mode where IQ current through the device is very less (33uA max). Also this allows a micro controller to turn on or off the device.

    Ans to Question 3:

    Before i can answer this, i need to know if the device is configured to run in circuit breaker or current limit mode?

    Regards,

    Kari.