Help with wiring up DC converter

[Stephen Mccormick]

Hi everyone,

New to the forum and electronics as well, Im trying to improve the the performance/efficiency of my power converter set up. The purpose of this converter is to be an portable adjustable power supply. It has been working well with the current set-up but i would like to improve it.

Background Info:

I have a Emerson SIL40C2 dc-dc converter with a 2 cell 18650 30a in series 8.4v li-on battery input source. Input, output, and ground circuits are wired using 18awg silver coated solid core wire. The battery source input circuit is interrupted by a mechanical switch to turn the device on/off.

I have a led voltmeter and a trim pot attached to control voltage output. All connections, contacts, and wiring are using high current large copper contacts and direct soldering with few as possible solder joints and threaded connections. No other external components were added other than mentioned above. space saving is crucial.

Goals:

-I want to isolate the switch from the input circuit, possibly using the remote on/off circuit. Im not sure how to wire up a bipolar signal transistor and what pins to use to accomplish this.

Also, when using remote on/off the board goes into a low dissipation sleep mode I would like to have no unneeded drain on the batteries so how could this be implemented so that this doesnt happen?

-Wiring up a simple digital pot with external up/down buttons. would like an idea of necessary components and wiring process.

-Determine the use of the Enable, Power Good, and (+) sense pins and if these would be beneficial.

-Increase performance and efficiency

Any help with these goals would be greatly appreciated!

View attachment an_sil40c2_1238193426_appnote.pdf View attachment sil40c2_1191532440.pdf

 

[BradtheRad]

I want to isolate the switch from the input circuit, possibly using the remote on/off circuit. Im not sure how to wire up a bipolar signal transistor and what pins to use to accomplish this.

Also, when using remote on/off the board goes into a low dissipation sleep mode I would like to have no unneeded drain on the batteries so how could this be implemented so that this doesnt happen?

Any device in readiness, will also need to be powered, so it can be in readiness.

This means if you wish for the device to power up by remote control, then you cannot disconnect the device from the battery.

 

[Stephen Mccormick]

Any device in readiness, will also need to be powered, so it can be in readiness.

This means if you wish for the device to power up by remote control, then you cannot disconnect the device from the battery.

So for my application if i wanted to use the remote on/off i would need a latching power switch on the input source to stop unwanted slow drain on batteries which is what I had figured, unless theres a way to control this digitally via one switch, i would like isolate the input circuit so that there are no mechanical switches limiting the input current, any ideas? thanks for the input!

 

[BradtheRad]

The SIL40C2 appears to be one of those modern devices which is designed to go to sleep, consuming ultra-low power.

To turn it off, you must pull the Enable pin low (below 0.7V). A pull-down resistor can do this.

Then to turn it on, you pull the pin high (above 1.2V). A transistor can do this.

But the transistor will need to be on all the time you want the device to be on (from what I can tell). An RS flip-flop can do the job. It is easily made from two transistors. Or perhaps a single-input toggling flip-flop.

This can be made to respond to your remote control. Push to turn ON, push again to turn OFF. Is that how you want it to work?

 

[chuckey]

If you want minimum current drain, I would use a FET with its gate connected to the + line via a 10 MΩ, so the current taken by this resistor is 16 µA. Take the gate via a 10K resistor and the earth of to your on/off switch, short circuit to turn off. Across the drain load of the FET connect the B and E of a PNP transistor, connect its collector to the -Ve via a load resistor (2K?). Across the load resistor connect the B and E of a NPN medium power transistor, its collector having a suitable relay and free wheeling diode. the theory is that with a S/C on the on/off wires all the transistors are OFF and with the on/off line floating, all transistors are on.
FRank