[Ben] wanted a switch mode power supply for his breadboard. He ordered a PTH08080 module which is made by Texas Instruments. The spec sheet would make it a great choice for him, but he was not happy to learn that the pinout doesn’t conform to the 0.1″ spacing used by solderless breadboards. His solution was to make a breakout adapter from some protoboard.
The PTH08080 can source up to 2.25A. It accepts 4.5-18V input and can output 0.9-5.5V. The best part is the efficiency that a switch mode supply achieves compared to linear regulators. This design adds in two capacitors which are suggested in the application circuit from the datasheet (PDF). Notice that there are two headers on the breakout board. One supplies power and ground to the breadboard. The other gives him a place to connect the adjustment resistor used to select the output voltage. This connects between one pin on the PTH08080 and GND. [Ben] plans to upgrade the design by included a precision trimpot for easy output voltage adjustments.
Looks nice, I’ll have to remember this design when I go prototyping again
i have been using these switch mode dc converters for a few months now as a trickle charger for my desulfator circuit. they are extremely easy to set up and very efficent. i power mune from old laptop power supplies and set the voltage for 13.50vdc and it keeps the battery floated while desulfating.
agreed, they are pretty damn useful! I’ve used these to MASSIVELY reduce a giant PSU rack design to just a single circuit board.
Someone at TI was having a “good-day” when they made these!
I have used lots and lots of the KIS-3R33S module, a similar buck converter that’s available used but in good condition from china. I have ordered about 150 of them and only come across a couple that were broken.
Yeah, me too. Used ones are dirt cheap on Ebay and well worth it.
TI has a few similar switching regulators that work quite nice. They default to 5v output if you don’t have the adjustment resistor connected.
And of course, TI is AWESOME for sending out free samples of their parts – this regulator costs $5.73 in quantity, and they’ll send you a couple through fedex for free with no hastle.
A review on the TI website shows that this supply has a 21 MA transient current draw when not powering any load. I’m assuming that is with the enable/interrupt pin not grounded, but even then, that is a hell of a draw for battery power projects, quickly kill a battery if not controlled.
Can anyone confirm?
That is probably true. Switch-mode power supplies basically cannot operate with zero load (the equations break down), so its possible there is a small dummy load in there to keep it stable.
Look at other models, some of them have an enable pin that should put it into a much lower state of sleep
It’s 1 mA. 21 Mega-Amps is a bit… too much.
You can compare this to the 5 to 10mA drawn by a LM2574
Sorry, I meant 21 milliamps. The datasheet shows 1ma when you bring the inhibit pin to ground, but what about when it is not?
My fault….leave /inhibit floating.
woohh, I was tired while writing the fisrt message and not woken up while writung the one above….
If I can find time, I’ll try to measure zero-load consumption for different output voltages
With a bit of pin bending, you can also solder it directly to a 3-pin connector and use it as a 78xx replacement.
You simply need to tie inhibit to GND with a small wire and put the configuration resistor on side of the module.
Trying inhibit to ground disables the module!
The module works just fine if you leave the enable pin floating.
Sorry, I made a mistake….
i meant to ask anyone, after pkaying witg a fee of these what style pinout is this package? it doesnt even line up with standard through hole protoboards.
The row of 2 pins are 0.1″ spaced, though the pins are too fat. The center of the row of 3 is also aligned by 0.1″ to the row of two. The outer two however are approximate 0.15″ from the center pin instead of 0.1″. The datasheet will give you exacts.
TI makes some very impressive DC-DC converters and related bits.
If you’re like me, once you’ve worked with one or two, you wind up spotting their relatives on all kinds of kit.