Low Power High Voltage Flip Flop...

[rhor...@gmail.com]

I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there is a twist. The device runs on a 6S Lithium battery, so the voltage will vary from about 18V to 25V or so. In addition, I need the power control circuit to use very little current - on the order of 100 uA - when off. It can use much more power when on - 20 mA or so is no problem.

 

[Anthony William Sloman]

On Monday, January 30, 2023 at 8:16:01 PM UTC+11, rhor...@gmail.com wrote:
> I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there is a twist. The device runs on a 6S Lithium battery, so the voltage will vary from about 18V to 25V or so. In addition, I need the power control circuit to use very little current - on the order of 100 uA - when off. It can use much more power when on - 20 mA or so is no problem.

You should be able to build a J/K flip-flop with discrete transistors - there are N-channel and P-channel MOSFETs that can take that kind of voltage.

The gate-oxide isn\'t that robust, so you might need level shifters to make the logic work. It won\'t have to be that fast, so the level shifters won\'t need a lot of current.

Classic CMOS is good for logic rails up to about 18V, but if there a 25V version I haven\'t heard of it.

--
Bill Sloman, Sydney

 

[Tauno Voipio]

On 30.1.2023 11.15, rhor...@gmail.com wrote:
> I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there is a twist. The device runs on a 6S Lithium battery, so the voltage will vary from about 18V to 25V or so. In addition, I need the power control circuit to use very little current - on the order of 100 uA - when off. It can use much more power when on - 20 mA or so is no problem.

You may need to build a debounce circuit for the switch, else
the response may be erratic, as the F/F will count the parity
of the contact bounces.

--

-TV

 

[Fred Bloggs]

On Monday, January 30, 2023 at 4:16:01 AM UTC-5, rhor...@gmail.com wrote:
> I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there is a twist. The device runs on a 6S Lithium battery, so the voltage will vary from about 18V to 25V or so. In addition, I need the power control circuit to use very little current - on the order of 100 uA - when off. It can use much more power when on - 20 mA or so is no problem.

You may think you need that, but actually you don\'t. You can most likely replace your existing switch with one of the exact same form factor that serves the on/off function. It will be called a \"latching\" on/ off switch.

 

[Ricky]

On Monday, January 30, 2023 at 5:16:01 AM UTC-4, rhor...@gmail.com wrote:
> I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there is a twist. The device runs on a 6S Lithium battery, so the voltage will vary from about 18V to 25V or so. In addition, I need the power control circuit to use very little current - on the order of 100 uA - when off. It can use much more power when on - 20 mA or so is no problem.

There are a number of simple circuits using a pair of transistors, which will do what you need. They take advantage of charge being stored on a capacitor to change the state of the circuit with the same push button. A Google search turned up a number of possibilities. The FET based designs can be very low power when off, however, you will need to find FETs with gate to source voltage ratings to match your power source. I would look for at least 30V.

https://www.google.com/search?client=firefox-b-1-d&q=push+button+on/off+circuit

Here\'s a page with FET devices. The link is long, so you may need to patch it up from this post.

http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/electronic-circuits/push-button-switch-turn-on/latching-toggle-power-switch

Figure 3 has the basic circuit. Other variations add different features. Figure 9 works with higher power source voltages. If you don\'t have a low voltage regulator, you can use resistors to step down the output voltage.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[bitrex]

On 1/30/2023 4:15 AM, rhor...@gmail.com wrote:

I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there is a twist. The device runs on a 6S Lithium battery, so the voltage will vary from about 18V to 25V or so. In addition, I need the power control circuit to use very little current - on the order of 100 uA - when off. It can use much more power when on - 20 mA or so is no problem.

Is a latching relay too simple a solution:

<https://www.electronicdesign.com/technologies/analog/article/21806385/relaybased-onoff-flipflop-remembers-state-during-power-failure>

 

[John Larkin]

On Mon, 30 Jan 2023 01:15:57 -0800 (PST), \"rhor...@gmail.com\"
<rhorerles@gmail.com> wrote:

>I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there is a twist. The device runs on a 6S Lithium battery, so the voltage will vary from about 18V to 25V or so. In addition, I need the power control circuit to use very little current - on the order of 100 uA - when off. It can use much more power when on - 20 mA or so is no problem.

You may not want to use this

https://www.dropbox.com/s/okjq1x7q0ftbfig/Momentary_Nfet.jpg?raw=1


but it\'s a fun circuit.

A version with two fets would stay on/off forever.