Low power 1.8V to 12V buffer?

[Plecto]

Hi. I'm looking for a way to convert a 1.8V signal to 12V with very low power consumption. I can't find any buffers or level shifters that can support 12V (ideally 16V to be sure), and mosfet drivers usually consume too much current. My best solution so far is to use a TPS2828 with a level shifter, but I was hoping to find a chip that can have all in one, is there no such chip?

 

[KlausST]

Hi,

MOSFET drivers consume too much power? I wonder. What specific device are you talking about?

Did you consider to use a comparator?
In either case if power consumption is critical, then you should give a specification. Value with unit, please.
And other specifications like:
* drive current
* signal waveform
* frequency
* expected dV/dt

Klaus

 

[abu_bua]

* Do you need a push-pull structure or is it possible to use open drain?

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Looking at the datasheet, https://www.ti.com/product/TPS2828, you will have problems! Vcc_min = 4V !!
RTFM!

- - - Updated - - -

Something like that should work if you really need a push-pull stage.
Select the mos transistors carefully (Vth, the input has to fully switch the resistor branch). A better solution would be to take a differential stage, because if you don't carefully select the time constants, you will have a very high current trough (M4, M5).


This is even better!!



As posted before, a if possible, a open drain makes life easy if possible.

 

[asdf44]

I'll second Klaus's suggestion of "gate driver" and comparator.

I can believe gate drivers may not be optimized for very low power but I'd expect to find low power 12V comparators out there with 1uS type, maybe less, propagation delay.

You didn't specify speed/load so we can't help further.

 

[Plecto]

This is my best solution so far:



It draws a maximum of about 10uA, almost all of it from U56. Vbat is about 11V and it has a positive going threshold voltage of maximum 7V at 10V supply which is the reason for the inverter + mosfet buffer circuit. I would love to find a gate driver like the TPS2828 that has TTL input threshold voltage levels which would eliminate the buffer circuit.

To answer the questions about spesifications. I regard 10uA of current draw as whats maximum allowable and it has to have a push-pull output stage. A ultra low power gate driver with TTL input would be ideal, but I can't seem to find anything better than the TPS2828. It should be able to produce a 115200hz square wave.

 

[KlausST]

Hi,

It draws a maximum of about 10uA,

I doubt this.

According ohm´s law @ R75:

I = V / R = 11V / 10kOhms = 1.1mA (= 110 x 10uA)

Klaus

 

[asdf44]

On a quick look I don't come up with a comparator to meet these specs. I see TLV3701 which meets the power specs but is too slow.

TLV3201 has 40uA draw but meets the speed requirements. Perhaps if you relax your current specs you can settle on a compromise in-between.

Note that on a quick calculation I can see it potentially 'costing' several more uA of draw just to drive that 12V switch node at 100khz

 

[KlausST]

Hi,

some update on power supply current.

You talk about 10uA of supply current and calculate this current for a steady state.

On the other side you talk about 115200 Hz square wave.
Do you know that every 7pF of load capacitance adds another 10uA of power supply current?
Now a CAT6 cable has about 50pF of capacitance per meter.
Thus every 14cm of CAT 6 cable adds another 10uA of power supply current. (for a cable length < 800m)

Klaus