Low cost low frequency oscillator

[Jester]

I have the need for a low frequency (say 1kHz) oscillator as follows:

- Really inexpensive
- Reliable start-up -40 +90 deg C
- 0-5V output @ <10uA
- Accuracy 20%
- Duty cycle 25 - 75%
- power source; +5Vdc

The tried and true 555 circuit is pretty cheap: $0.44@qty10, or $0.22@qty100 (Digi-Key pricing)

Does anyone have a cheaper or more elegant solution?

 

[andre_luis]

Certainly not more elegant, but doing that with NAND is cheapest: $0.13@qty100
https://www.digikey.com/product-detail/en/CD4093BM96/296-25956-2-ND/1691444

 

[wade_hassler]

How about a single-gate Schmitt-trigger oscillator?
Digikey has 74AHCT1G14SE-7DITR-ND at $0.0425/3000

 

[D.A.(Tony)Stewart]

'HCT14G may be best price readily available.

But do you need to guarantee 20% accuracy with a 10% supply over wide temp with what tolerance cap?

 

[Jester]

'HCT14G may be best price readily available.

But do you need to guarantee 20% accuracy with a 10% supply over wide temp with what tolerance cap?

Actually for this application, the frequency is not critical at all, I can live with 50% accuracy.

I like the proposed solution, not only is it less expensive, it uses a smaller package (SC-70 vs. SOIC8) and one less component.

Thank you.

 

[Audioguru]

The ordinary 555 with a 5V supply has an output that is a minimum of only 2.75V if it has no load. The 555 draws a fairly high current all the time.

 

[D.A.(Tony)Stewart]

CMOS version of 555 takes 30uA https://www.digikey.com/product-detail/en/ICM7555ESA+/ICM7555ESA+-ND/1303147

 

[KlausST]

Hi,

any comparator should do. and three resistors and a c. plus a c for vcc decoupling.

it is very stable in time and has good stability on VCC change. Temperature drift is more a problem of the used C.

I don´t know if this solution is cheaper than others.

Klaus