Low-power clock generation

[elockpicker]

Hi everybody,

Is there any IC (or something) that generates ultra low-power clock signal (less than 10MHz) ?
I mean it consumes very little power and generates a clock signal.

Are crystal based clock generators considered low-power?

Thank you

 

[FvM]

What do you consider low power respectively ultra low power? What are your additional requirements for the clock signal?

 

[elockpicker]

The clock frequency should be between 1Mhz and (almost) 10MHz.
The supply voltage should be between 1.2v and 3.3v
IO levels of clock signal should between 1.2

It's gonna drive a low power FPGA from Actel (Igloo series) so i think it should consume a very small amount of power.

Thank you in advance

 

[FvM]

Some industry standard crystal oscillators have supply currents below 10 mA. If you want much lower currents, you possibly need to design your own circuit.

 

[elockpicker]

Thank you,

but I need something that consumes current in order of uA ? Is there such a thing available?

 

[FvM]

The current consumption of the active (clock supplied) Actel FPGA will be surely higher than a few uA. But I agree, that you may want to design your own crystal oscillator. A low voltage (e.g. 1.2V supply) unbuffered inverter CMOS would be promising in my opinion.

 

[elockpicker]

Do you mean the usual (simple) crystal and Not Gate oscillators using a low power CMOS inverter ? is such inverter available as a discrete component?
Thank you

 

[FvM]

See LVC single gate unbuffered inverters, that can work down to 1.8V
https://www.ti.com/lit/ds/symlink/sn74lvc1gx04.pdf
https://www.ti.com/lit/ds/symlink/sn74lvc1gu04.pdf

AUP family, has even lower power dissipation capacitance and can work at 1.2V, unbuffered inverters are available from NXP


The problem is, that usual crystal load capacitors involve a much higher power dissipation than the internal AUP capacitances. For minimal power disspation, you may want to accept a small frequency offset and reduce the crystal load capacitance.