<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">All, <div class=""><br class=""></div><div class="">OK, before you say it, yes, I first consulted Google before sending this note. I have not worked with these devices before and the latch operation is the part that I find most confusing. The best device I could find was the <a href="https://datasheets.maximintegrated.com/en/ds/MAX9140-MAX9144.pdf" class="">MAX9141</a> but the operation of the latch in figure 2 was not what I expected. </div><div class=""><br class=""></div><div class="">I am looking for a simple circuit which will do the following:</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- Powered, Vcc, by either 3.3V or 5V and should not consume more than 100uA.</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- Connect to the analog output (ranges from 0 to Vcc) of my <a href="http://www.maxbotix.com/Ultrasonic_Sensors/MB7363.htm" class="">Ultrasonic Range Finder</a> with a high input impedance - potentially with a low-pass filter - we will see.</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- Allow me to set a “trigger threshold” ( 0 to Vcc) using a potentiometer </div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- Compare the input to the trigger and provide a latched digital “high” when the input exceeds the threshold</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- This signal will wake the micro controller using a hardware interrupt and trigger an interrupt routine.</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- The comparator will hold the line “high” input until cleared by the micro controller</div><div class=""><br class=""></div><div class="">Anyone who has a few minutes to take a look please let me know:</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- Is the part I found the right one?</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- Is there a better solution - perhaps using discrete components?</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Thank you,</div><div class=""><br class=""></div><div class="">Chip</div><div class=""><br class=""></div></body></html>