Extremely low power 30 seconds delay

[luben111]

Hi,

I need 30s to 60s fixed delay and the whole schematic should consume less than 10uA. In addition the solution should be as smaller as possible (SOT23 or smaller).

I looked at some watchdog IC like ADM8316 and they seems to look OK for my purposes but the price is too high.

Any ideas will be appreciated.

Kind regards,
Luben

 

[BradtheRad]

This simple method does what you want. Current draw is less than 10 uA, until the first transistor turns on.

However the capacitor will take up a lot of space.

 

[Analog Ground]

Analog Solution: Can you provide more information on the 10uA requirement? Is it an average of 10uA and perhaps more during the delay? Or, 10uA maximum during the delay? If an average, what is the rate of the delay? Once per hour? Per day? As #2 above points out, 10uA maximum during the delay done with analog timing (a capacitor) needs approximately 300uF which has a high cost and size. If the 10uA is an average, there are more options.

Digital solution: PIC12LF1840 microcontroller, DFN package, <10uA at low supply voltage and 32 KHz (LP oscillator) mode, ~$1.00 in quantity.

 

[yogece]

look at**broken link removed**

Touchstone semiconductors TS3005 timer operates at extremely low current and it requires a single resistor to program the delay

 

[luben111]

Hi,

Microcontroller is too expensive solution - my target is to get the whole PCB for less than 1$, it's mass production design. TS3005 is a good solution but also expensive. I came up with a solution with cheap CMOS single gate with Schmitt input.

The average power consumption should be below 10uA but current spikes are acceptable.

Thank you for the suggestions.
Luben