3.3VDD Pulse Width Extender schematic

Community Chit Chat
1

Hello,

I’m in the need of the right Sparkfun part or general help if someone would help me. I’m using a LeadTek GPS board which uses an SiRF GPS receiver. The SiRF outputs a PPS (Pulse Per Second) pulse which is 2.5V and 1usec wide. (3.3VDD) This pulse width is not long enough to trigger my input on my RPi 4B GPIO input, which requires the same 2.5V (3.3VDD) but much wider pulse; something in the range of 10msec.

I have tried a couple of circuits using a 74AHC123A Monostable chip and a CD4047 Monostable chip. The problem with these is they don’t support 3.3VDD. If I use 5VDD they work but then my output pulse over drives my input on my RPi.

Does Sparkfun have a device or two that can do this conversion? Or can someone on here recommend the proper IC chip that will do this?

Thanks for reading.

2

Something like this might work?

http://www.555-timer-circuits.com/monostable-555.html

If you need to convert 5 volt logic to 3.3 volts, a [resistor voltage divider would work or you could use a semiconductor logic level converter like a 74HC4050 or even sparkfun’s [bob-12009.](https://www.sparkfun.com/products/12009)](Voltage Divider Calculator)