MCU Power Enable IC with Delay Timer

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Good evening,

 

I'm after a pretty straight forward functionality, but I'm struggling to find a suitable IC.

 

My circuit is permanently connected to an automotive battery. In order to enable power to the circuit, I'd like to use a supervisory IC which toggles the ENABLE pin of my circuit's PMIC high when a switched input, interfaced to the supervisory IC, goes high (e.g. accessory source). When the switched input goes low (i.e. the car is turned off), I'd like to have a delay before the supervisory IC toggles the ENABLE pin of the PMIC low.

 

Is something like the LTC2954 more or less what I'm after? It's designed for an active low push button, so I'll need to invert the logic there (with a MOSFET of some sort I'd imagine), but it provides an interrupt to the MCU when the monitored voltage drops, which is exactly what I'm after. The LTC2954 is a bit more costly than I'd like, so any suggestions of lower cost alternatives would be great!

 

Any guidance would be greatly appreciated, even if it's a recommendation as to which search terms I should be using. Most of my searches result in watchdog timer and PoR ICs.

 

Thanks!

This topic has a solution.
Last Edited: Tue. Sep 4, 2018 - 07:10 AM
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A common solution would be to use a small microcontroller methinks.

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I can definitely see how that might be a solution, I was hoping for something less involved if possible. I can make the LTC2954 work if there are no better options; I'd probably go for the IC approach over a dedicated MCU to be honest.

This reply has been marked as the solution. 
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For anyone finding this in the future, looking for a similar solution, I've ended up going with the LTC2954 :)

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jars121 wrote:
For anyone finding this in the future

Help them by marking the solution - Tip #5

 

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Done, thanks for the reminder :)

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yes

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...