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I am looking for a IC which would perform an RS flip-flop function and watchdog

carlosgdj07
Prodigy 240 points

Hello everybody,

I am trying to develop a system which would allow my micro-controlled system to switch off the main DC/DC converter by toggling a GPIO (3V3) to perform a scheduled power-off sequence and the system to be powered-up by pressing a button.

Apart from that, It would be perfect if the system when ON, it performs a watchdog timer that reboots the system if it were not cleaned within a fixed period periodically.

Please find attached a draft of what I want to do...

 

Would it be possible to have an IC which performs that RS + watchdog function or kind of??

I have designed an RS system (Reset from 3V3 signal and Set from pushbutton) with transistors and resistors but it involves to deal with a lot of space in PCB...

Many thanks and best regards,

Carlos González.

  • 0
    TI__Genius 12630 points
    Carlos,

    It sounds like you need a reset IC with /MR (manual reset like a button) and WDI (watchdog).

    I would recommend starting with TPS382x family (there are various output topologies to choose from).

    www.ti.com/.../tps3825.pdf

    If you need extra programmability, or if you want a separate output for reset and watchdog, we have those options as well. Provide feedback on if this is what you are looking for.

    -Michael
  • 0 in reply to Michael_DeSando
    Prodigy 240 points
    Dear Michael,

    Thanks for you reply but I am afraid that it is not waht I am looking for...

    I need a chip which controls the enable of a DC/DC without supervising any voltage.

    It will enable that DC/DC when a pressbutton is pressed and remain in this state regardless of how many times this button is pressed or released.

    It should disable that DC/DC by receiving a 3V3 signal from a uC and keep that DC/DC disabled until the pushbutton is pressed again.

    That is the classic behaviour of a RS / JK flip-flop. The special thing I want to do is to add a watchdog feature and the circuit to be powered at 12V...

    I don't know if there is any IC which would be capable of doing all of that in one single chip...

    Is there any chip which performs a reset signal if a pulse is not applied periodically? Maybe I could add that chip to my circuitry to add that watchdog feature...

    Best regards,
  • 0 in reply to carlosgdj07
    TI__Genius 12630 points
    Carlos,

    As for a single chip solution, we don't have any to accomplish those requirements. The TPS382x family has the Watchdog feature which will cause a reset if not triggered periodically. For the latching behavior, you will have to add external circuitry and utilize the manual reset feature. We have circuit simulations to show how to latch our voltage supervisors. We have also created push-button ICs that toggle the output each time the button is pressed but it sounds like you want a push-button toggle + latching circuit. You might want to use an RS / JK flip-flop type of device with the watchdog reset IC. Another issue is that our watchdog devices have max input voltages of around 6.5V. So I am not sure we have a solution that will work for 12V. We could possibly create something but again, the max input voltage would be around 6.5V and the solution would require multiple devices and external components.

    -Michael
  • 0 in reply to Michael_DeSando
    Prodigy 240 points
    Dear Michael,

    Manu thanks for your advice and knoledge. I will implement the external watchdog with your TPS382x family in addition to my latch circuitry.

    Best regards,