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TL594: disabled

user1881876
Prodigy 230 points
Part Number: TL594

Tool/software:

Hello.

I am making a charger using TL594.

When charging is finished, the DTC terminal is pulled up to the reference voltage by a signal from the CPU. Even if the DTC terminal becomes 5V, operation does not stop.

Are there any conditions for the DTC terminal to continue operating at 5V?

This may be because the FET is driven by Bootstrap.

Please let me know if there are any mistakes in the circuit.

Thank you.

TL594_circuit_2410.pdf

  • 0
    TI__Mastermind 33115 points

    When the CPU applies the EN signal, what is the voltage measured directly at pin 4 (DTC) with respect to GND? When the EN is LOW, what is the voltage measured directly at pin 4 (DTC) with respect to GND? 

    Also, how do you determine "operation does not stop" - can you show some waveforms of C1, C2, DTC, EN when EN is HIGH and when EN is LOW?

    Also, if the intent is to disable the TL594 when charging is finished, you can also pull CT to GND as mentioned in this E2E post here.

    Regards,

    Steve

  • 0 in reply to Steven Mappus1
    Prodigy 230 points

    Thank you for contacting me


    The voltage applied to pin 4 (DTC) is pin 14 (5V).

    The specifications of this charger are to check the presence or absence of a battery by using a loopback signal when the battery is connected.

    Therefore, the EN voltage behaves as follows.

    The current problem is that it does not turn off at ③.

    ① Before battery recognition EN: Low
    ② After battery recognition EN: High
    ③ When charging ends EN: Low

    I added an additional circuit to pull down CT to GND, but the result was the same. Please check the waveform in Fig. 4.

    Wave form_TL594 .pdf

    Thank you

  • +1 in reply to user1881876
    TI__Mastermind 33115 points

    If the oscillator is not operating (CT to GND), there can be no output but you have C1, C2 pulled high to +10V. There must be some other charging path - you need to debug and figure out why the output is still charging? Maybe try to temporarily disconnect the circuitry from C1, C2 and jjust verify to your self that the IC is responding to DT pull HIGH and/or CT pulled LOW?

    Steve