Hi guys, I ordered a 4-BRIDGE SERIAL INTERFACE MOTOR DRIVER for my stepper motor to hooked up to my arduino uno. I was very excited for it was FREEE (luv TI!!) and i could finally get started…but the chip is one of those tiny chips!!!..too small to fit on my breadboard. any suggestions. i googled and found that i need a surf board on which the chip will be placed and that surfboard will go on to my bread board…sounds nice. I looked on ebay for “surfboard” and guess what i got as my results…surfboards!!!(as in surfing boards!!).
it’s a 48 pin HTSSOP. can someone please point me in the right direction as to where can i purchase one(a reliable source please). thanks in advance and i have attached the Data sheet for the driver. thanks again
luv life live life
drv8823.pdf (642 KB)
Have a look here
but also google for “smd breakout board”
Nice chip. Not a very friendly package, though. Aside for the itsy-bitsy pins, it had special heatsink requirements, so probably the only way to use it would be with a custom-made PCB
Whee. Here’s a “breakout” (untested, done as an experiment) specifically for the drv8823. In retrospect, I’m not sure this is a good idea; It looks like it gets all the need signals on a 20-pin 0.6inch DIP format, but a more generic HTSSOP to DIP adapter might be a better idea…
Always double check the package type before placing an order.
but a more generic HTSSOP to DIP adapter might be a better idea
But a generic board won't have the heatsinking you have included or the support passives.
westfw I think you are on the right track with that design, do you have a heatsinking plane on the other side of the board as well?
I might also be inclined to allow for adding more heatsinking like those heatsinks that mount over a DPAK, this sort of thing
Although there may be versions more appropriate for that chip.
And maybe move the centre pins (SLEEP and SCLK) aside so there's room to connect the PGND pins to something substantial to sink the heat.
It looks like the package dissipates heat quite nicely with low C/W figures but these are always based on a JEDEC test board that's huge so if you really want to use the chip to it's potential you have to pay attention to dissipating the heat.
I sort of meant "generic with heatsink tab"; those center six pins on each side and the bottom pad all connected to a big GND plane, and all the other pins broken out separately. That's a lot of broken-out pins though (48-12 = 36 !)
Yes, there's a bottom pad too, about the same coverage as the top. I guess there should be more, if I want full current to be
possible. I'm not sure I understand TI's info as pertains to double-sided boards; their text says single-sided, the graph says double-sided, and I'm not sure how total board area relates to copper area when there are signals on the relevant sides (an internal ground plane on a 4-layer board is going to be almost all copper, with a sprinkling of vias...)
But I guess more copper would be better; at least expanding the board to the size of a 24pin or 28pin DIP?
I dunno about sticking in a finned heatsink of some kind...
(so it's looking like the current sense resistors need to be high-power things capable of passing the full motor current(s) rather than the tiny SMT things I put on the board. That's a bit depressing. 4x 2W resistors have about the same volume as the entire rest of the circuit; probably more...)
4x 2W resistors
It looks like you can get 2W SMD resistors in 3.2mm x 6.4mm packs, is that too large?
Well, it’s painfully large for the current PCB (or any PCB narrower than the 0.6 inch I’d consider about the max size for protoboard compatibility.) Also, it’d end up dump double the power into the PCB copper, which is certainly undesirable if I’m trying to use it as a heatsink. (Rsense needs to be about .5ohm, Rdson of the H-bridge is about .3ohm…) (clarification questions have been posted on TI’s forums.)
**EDIT:**TI confirms that full motor current flows through the sense resistors. You can leave them out, but you lose current sensing and the “partial power” features. They recommend small-value resistors (you might get away with 1/2W resistors if you use Vref=1V (which is the min recommended) and R = .167 ohms (Imax = 1.2A))