One of the things every good hardware hacker is nothing without is the ubiquitous soldering iron. For something whose sole purpose is to get a bit toasty, there is a heck of a lot of engineering that goes into such a device.
Going from an AC/DC input of varying magnitude and producing a tip temperature that is regulated finely enough to melt your solder, without charring your FR4 takes a bit of planning.
If you aren't up for the design challenge justyet (maybe you don't have a soldering iron to assemble your design?), you can pick up a pretty good hobbyist level iron in the form of the TS100, which despite sounding like one of the Terminators, a bit more reserved in function.
The TS100 provides a neat little all-in-one soldering tool, featuring DC input, user interface (OLED, buttons) and complete control board, all within a slimline handle workpiece.
It's not a free lunch, however. One of the main gripes from users of the TS100 is that it is a little lacking in power. That's a fair comment. Keeping that tip heated up while melting a blob of solder onto cold component legs can take a lot of energy.
While there is a sibling product, the TS80, that eschews the DC barrel jack for a USB-C interface, it's not quite as powerful as it could be - the power protocol used here is QC3.0 (The Qualcomm QuickCharge standard), which caps out at 9V @ 2A, which is a somewhat measly 18W!
So, why not just pick up a TS100, and construct an adaptor to take one of the soon-to-be ubiquitous USB-C PD "triggers?" Well, even then, the circuitry of the TS100 is pushing the limits of its capability at 65W, which is still not quite as good as it could be. Read on for the details.
Jan Henrik has given this situation a bit of thought, and come up with a really sensible approach — a complete TS100 drop-in mainboard of his own design, allowing him to bring in the powerhouse of USB-C PD and make use of all the power that can be pushed down from a "proper" USB-C PD source.
The top limit on USB-C PD is 100W, some five times more than the QC3.0 standard, so while we have yet to see much real-world testing on the Otter-Iron, we can be assured that it is going to come out with top marks against its class of rival, stock hardware.
Henrik has taken all the bits needed to make a powerful iron, not only in terms of electrical power, but processing also.
Let's break down the key parts to this little pocket powerhouse.
A beefy STM32F072 is the brains of the operation, with more than enough oomph to run a tight PID control loop.
The USB-C PD negotiation is handled by a dedicated PHY - The STUSB4500.
This is a neat little chip, that takes care of all the intricacies of actually speaking the PD protocol to whatever source is on the other end of the USB cable. With the option to have its configuration burned into OTP flash, this makes it a true plug-and-play option for USB-C PD.
Speaking of control loop, we need a hefty FET to handle switching that hefty current flow, and a DMP3017 provides +300W of capability, meaning that you'll (hopefully!) never come anywhere close to saturating it.
The trained eye may notice the programming header, just next to the Otter-Iron insignia. Rest assured, you only need to bust out the programmer once! A hardware selectable "DFU Mode" means that firmware updates can be sent down the wire of the USB port, simplifying future development efforts.
This all seems a lot of work, and sometimes, the challenge itself is enough to justify the project. As much as I agree with the sentiment, I think Henrik's reasoning below is enough to convince anyone that this was a sane endeavour!
You can catch the thread from Henrik on Twitter here, and if this project sparks your interest, you should probably d̶i̶s̶c̶o̶n̶n̶e̶c̶t̶ ̶t̶h̶e̶ ̶p̶o̶w̶e̶r̶ ̶b̶e̶f̶o̶r̶e̶ ̶w̶o̶r̶k̶i̶n̶g̶ ̶o̶n̶ ̶i̶t̶ give Henrik a follow on there.