Low frequency, <1% duty cycle, IC oscillator

[raff5184]

Hi,
Im looking for a low power (few microamps or even nanoamps) chip capable of generating low frequency PWM signals in the range of 50-200Hz but with a very small duty cycle, like 0.2-4%. i found several adjustable oscillators but in the MHz range, which helps with the d.c. but frequency then is a problem. Is there an IC that does this? I'm looking for a chip, if it even exists,  not how to make my own circuit

Thank you

[Picuino]

Perhaps with the ICM7555.
https://www.renesas.com/eu/en/document/dst/icm7555-icm7556-datasheet


EDIT:
Another option is a small uC in sleep mode controlled by watchdog.

[raff5184]

Will constant frequency (non or only in multiples of  2 adjustable) and constant pulse width (not constant duty cycle  but constant on time) suffice?

multiplies of 2 for freq is more than acceptable. What do you mean constant pulse but not constant duty cycle?

[raff5184]

Perhaps with the ICM7555.
https://www.renesas.com/eu/en/document/dst/icm7555-icm7556-datasheet


EDIT:
Another option is a small uC in sleep mode controlled by watchdog.

I'll take a look thanks. I tried a uC and it does the trick but in my case was absorbing too much. Any uC you'd recommend?

[Picuino]

The ICM7555 has an static supply current of 40uA @ 5V.

I would recommend you a low power PIC microcontroller (XPL).
https://www.microchip.com/ParamChartSearch/Chart.aspx?branchID=30048

Perhaps this one:
https://www.microchip.com/wwwproducts/en/PIC12F1571
https://ww1.microchip.com/downloads/en/DeviceDoc/40001723D.pdf

eXtreme Low-Power (XLP) Features:
  Sleep mode: 20 nA @ 1.8V, Typical
  Watchdog Timer: 260 nA @ 1.8V, Typical
  Operating Current: 30 uA/MHz @ 1.8V, typical

[Terry Bites]

TPL5110
Runs on ant farts.

[raff5184]

TPL5110
Runs on ant farts.

[Picuino]

However, if you power a PIC XPL with a small 200mAh button cell, it will take 87 years to use due to the consumption of the watchdog.
260nA of the watchdog consuption is 10 times more than the consumption of the TPL5110, but negligible anyway.


200mAh / 260nA = 769230h = 32051 days = 87,8 years