Stable oscillator

[WTP Pepper]

I am after the the following but cannot find anything that meets my spec so I would appreciate some input from the forum.

Single chip solution.
1Hz square wave oscillator
Current < 50uA
Temp compensated to less than 5ppm over 0-40deg C
3v operating voltage.
Non I2C control.
No RTC solutions as they draw current when actively being interrogated.
As small as possible.

I don't mind if 1Hz is derived from a higher frequency, but it still must be small and draw very little current and be temp compensated.

I want to wake a sleeping CPU every second to update a UNIX timed counter clock and do a few checks before going back to sleep. The CPU runs on an internal 10KHz clock during this "wakeup" period and draws microamps. I want the clock to not draw too much of this current budget. Otherwise the CPU is sleeping and drawing a few of microamps.

TIA

 

[ccurtis]

Have you seen this? Use in single supply (battery only) mode. A CMOS binary divider brings it down to 1 Hz.

https://www.electro-tech-online.com/custompdfs/2012/10/DS32kHz.pdf

 

[WTP Pepper]

Thanks for that. If I can use on Vbat only then the 32K output would work fine for my app as the CPU draws little on an external clock.

 

[ccurtis]

My pleasure. It's curious that there's a comparator activated in the dual supply mode that uses over 150uA that is deactivated in single supply mode. There are comparators available that use much less current than that. Anyway, in single supply mode the device uses only a few microamps (except during the low duty cycle temp update) and with only slightly less freq stability.