Heads up on Allegro A679EA-T

[fkostyun]

The Allegro chip has been flagged as obsolete by Digikey. Recieved an email earlier today from Digikey.

[lafrost]

Is there another to replace this chip???

[RavingLunatic]

This has been discussed before and some options can be found in this thread:

http://www.doityourselfchristmas.com/forums/showthread.php?t=9076

[Blackbeard]

After reading through all the threads and thread references, I still am not sure what I should try to use. Firstly, I don't have the boards, and I'm not sure where to get them or their cost, but I might try making my own with Eagle. If I do, I have the option of trying one of the different packages, and even some of the other manufacturers like TI. Going to the Allegro site and viewing what they show for the chip, it appears they aren't sending samples of any package of the chip anymore, since I didn't see a "samples" link anywhere. That could just be my old-age eyes though. TI does seem to have a chip that might be used with the .065 lead spacing (TSSOP), which isn't much worse than the .100 spacing of the DIL packages. There is also the .050 lead spacing (SOIC) versions. The part numbers for the TI chips are TLC5925, TLC5926 and TLC5927. The '25 has an output current max of 45mA while the other two have 120mA output with some extra functionality.

Does anyone have an opinion about the 45mA max rating? Is this enough? What is the rating on the Allegro chip set to? All of these chips have their output amperage set with the external resistor.

Thanks for any info.

steve

[P. Short]

Be careful...that .065" number that you quote is more likely 0.65mm, or .026" (approx), which is a lot smaller and more difficult to work with than .100". That, anyway, is the more usual pitch for the TSSOP package.

[wjohn]

I have the boards for the current LEDTRIKS / TRIKCS projects.

[Blackbeard]

Be careful...that .065" number that you quote is more likely 0.65mm, or .026" (approx), which is a lot smaller and more difficult to work with than .100". That, anyway, is the more usual pitch for the TSSOP package.

Right you are Phil. The datasheet listed some of the packages in inches(millimeters). The TSSOP was millimeters only. Looks like it's going to be the SOIC at .050 inches then for a test. Old eyes just don't catch things as well as they should.

The Ledtriks V6 appears to shoot for a constant current of .0189 amps with the 1K resistor, and the TLC5925 will give about .02178 with the same resistor. Other than that and the package, it appears to do the job.

Thanks for the correction, and wjohn, could you PM or email me the price of the boards. If I get anywhere with the Eagle stuff, I'll let you all know. Hope it's OK that I attempt this with the original designers.

steve