Eltek Flatpack2 touchscreen controller

An Eltek Flatpack2 48/2000 HE rectifier is being used as the power supply for a future RF Power Amplifier project.

This is the touchscreen controller being developed to control the Flatpack2, and display the data.

A few changes have been made since that video was shot, notably a more robust power supply.

These cheap 60V to 5V LM2596HVS based step down converters commonly available on ebay aren’t all they’re cracked up to be, and the LM2596HVS IC are most likely inferior ‘fakes’.

Image source: https://www.eevblog.com/forum/reviews/fake-lm2596hv-again/msg2009078/#msg2009078

So I started looking for an LM2596HVS IC from a reputable supplier, like RS Components.
… but they don’t stock it!

That raised a red flag, so I then researched suitable DC down converter chips that had a genuine high voltage input tolerance.

Enter the Maxim MAX5035, a “1A 76V High efficiency step-down DC-DC converter”, available in an SOIC8 package and with a fixed 5V output voltage variant.


From the datasheet application notes a power supply was designed, and a suitable PCB layout was created that also accommodated the connectivity for the Arduino Nano and the CAN bus adapter all on the one 10 x 5cm PCB.

25-7-2019 Update:

A batch of 10 PCBs arrived weeks ago, and it was time to assemble a board and get it running.


I’m a bit over green solder mask, so blue it was!


There is little point re-inventing the wheel, so instead of replicating the circuitry of an Nano and CAN-bus adapter, cheap and readily available modules simply insert into the controller “main board”.

Incidentally, it would have cost more to purchase the individual parts required  to replicate a Nano and CAN-bus adapter.

Above: Mounting arrangement.  CAN-bus adapter is upside down to access connectors.


Connecting the Flatpack2 to the outside world is by way of an adapter PCB purchased on eBay.

To power the controller board, two 0.9mm holes were drilled so that a suitable connector could be mounted to the PCB.

Solder mask was scraped away, creating two solder pads, for the connector.

Above: 4-pin 0.1″ pitch connector (with middle two pins removed) has been soldered to the interface PCB.

Above: Interface PCB connectivity.  Mains, CAN-bus to controller, and power to controller.


The controller board is mounted to the top face of the Flatpack2 using adhesive PCB supports.


Finished controller in action, with a Nextion 3.5″ (enhanced) touchscreen GUI.

This 48V (nominal) 2000W PSU is ready to integrate into a future 23cm LDMOS Power Amplifier project.

Since the video was shot, default voltage entry is now via a keypad, rather than the cumbersome slider control.


Screen brightness and a screen saver are configurable:


This controller allows monitoring of the parameters that Flatpack2 provides via it’s CAN-bus:
• AC Volts in
• DC Volts out
• Load current
• Intake temperature
• Output temperature
• Operating status
• and any alarm/warning messages it generates

A touch screen makes it easy to set the “default voltage”, change the foreground and background colours and font of each parameter via the “SET” menus. Some Icom terminology there. :wink:

Current voltage can also be shifted up or down in 100mV steps.

10 PCBs were fabricated, and I’m keeping one more, so 8 PCBs are offered for sale on a cost recovery basis.
You can have a copy of the schematic and BOM, but you’ll need to develop your own Arduino and Nextion code to suit.

Alternatively, I can provide a full turn-key solution at cost + a modest fee for time taken to order parts, assembly, programming x 2, test and handling.

Please inquire privately if you are interested.