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kenjinx
01-11-2008, 11:48 PM
Is the A6276EAT a suitable sub for the A6279EA-T? The Allegro rep told me that they were essentially the same chip pin for pin.

prof
01-13-2008, 08:24 AM
It should be OK to use

I have been looking into what chips are available, and of these which ones if any i could get hold of here in Australia.

Have not actually used any chips yet but initial comparisons of the data sheets shows they all seem to be suitable substitutes. (You will need to confirm for yourself if they really are suitable or not).

Maximum mA drive currents vary between chips as do the maximum voltage ratings of the outputs (should not be a problem if building a standard grinch or ledtriks) but you will need to confirm the resistor value for 20ma output current.

These are the ones that I have found so far, and it is possible that not all versions may still be available.

Allegro
The A6276 is the basic decoder driver.
The A6279 has extra circuitry for open circuit LED detection.

Maxim
The MAX6971 is a basic decoder driver with good low volt operation (3.3V) but lower mA drive (50mA).
The MAX6983 has added led fault detection and led shutoff on loss of input signals
MAX6969 is a basic decoder but the outputs can only handle a supply of 5.5V (which is not an issue on the standard grinch/ledtriks design as they work from 5V anyway).
MAX6983 has 5.5V outputs as with the 6969 with added led fault detection and led shutoff on loss of input signals.

STmicro
STP16C596 is a basic decoder driver (older generation)
STP16CL596 has good low voltage operation
STP16CP596 has precision current drive
STP16CP05 is the new generation basic decoder driver with thermal shutdown and low voltage operation.
STP16CDP05 has the error detction circuitry.
STP16CPS05 has shutdown detection (turns leds off if loses signals on data inputs).

Toshiba
TB62701 is a basic decoder driver

Note: I have not given the complete part numbers for specifying the 24-DIP package style, I have only listed the generic model number. Nor have I done any research yet into where any of these chips might be available in the US.

Hopefully some other users out there can confirm/deny the suitability of the chips I have named or add some more to the list.

Also just a thought. By using these chips with error detection (open circuit LEDs), could that be the reason some people have been getting odd behaviour with boards that have been found to have bad data/LED wiring? The error reporting mode is triggered by addressing the chip in a special way. Could the faulty wiring be tricking the chip into reporting its errors. Which it does by sending its error report through the data out pin. This then gets passed onto the next chip in line, causing it to display rubbish.

kenjinx
01-14-2008, 01:36 AM
I am trying to use the A6276EA-T (those were the only ones available). I cant seem to get the Grinch to work. I have the LPT port set to EPP / I set vixen to use plugin Olsen 595 (64 CH) / I am using the computer for the 5V supply (reads 4.97V) / The LEDs on the Grinch and the SSRs light / The lights will come on (constant) when I turn on the computer but as soon as I run a vixen sequence or test they turn off and stay off. Anybody have any troubleshooting suggestions?

prof
01-14-2008, 05:47 AM
Assuming you are using co-op boards then the only LED on the grinch is across the supply and should stay on all the time it is powered up ditto SSRs. The fact that they go out when vixen accesses the LPT port when it attempts to run a sequence is a clear indication of a wiring error in your DIY cabling from the parallel port and PSU power to the grinch. Probably the 0V link from the PC to the grinch is missing or incorrect. If you are bringing power in through the RJ45 connector then the shunt needs to be inserted on J1

coolspot
01-15-2008, 06:51 AM
can you use these ones A6279ELW-T

prof
01-15-2008, 08:33 AM
The A6279ELW-T is a SOIC surface mount package not the DIP version.

kostyun
01-15-2008, 10:37 AM
I also have the Maxim MAX6969, which appears to be compatabile.

kenjinx
01-15-2008, 11:01 PM
I am trying to use the A6276EA-T (those were the only ones available). I cant seem to get the Grinch to work. I have the LPT port set to EPP / I set vixen to use plugin Olsen 595 (64 CH) / I am using the computer for the 5V supply (reads 4.97V) / The LEDs on the Grinch and the SSRs light / The lights will come on (constant) when I turn on the computer but as soon as I run a vixen sequence or test they turn off and stay off. Anybody have any troubleshooting suggestions?


The lights that go off when Vixen is ran are the Christmas lights. The LEDs are constant ON.

JEEPGUY
01-16-2008, 01:25 AM
Kenjinx,
Are your chips set in the correct direction? How about the triacs? Can you post a picture of the Grinch and the SSR?

kenjinx
01-18-2008, 01:24 AM
The LPT port was the source of my problems. I hooked it up to another computer and it worked fine. Thanks for the advice!

To sum things up, the Allegro A6276EAT is a suitable sub.

derekhessman
01-18-2008, 06:36 PM
I requested samples of both the A6279EA-T and the A6276EA-T. Both requests were processed. The A6279EA-T chips never showed up. The samples of the A6276EA-T arrived in less than a week.

If you need chips, request the 76, they have those in stock.

daviddth
01-18-2008, 10:04 PM
Thanks - ordered the A6276EA-T samples, so I'll see how they go for us people "down under"

dnesci
01-19-2008, 02:19 PM
SOLD OUT If anyone wants to buy the A6279EA-T , I purchsed in bulk and will sell at cost. See

http://www.doityourselfchristmas.com/forum/viewtopic.php?t=2510

derekhessman
01-28-2008, 10:18 PM
Well, the 79's I requested came in the mail today. They must be back in stock. Does anyone know if you mix and match the 76's and the 79's? ie if you used 4 79's and one went bad could you put in a 76 and have then play nice together?


I requested samples of both the A6279EA-T and the A6276EA-T. Both requests were processed. The A6279EA-T chips never showed up. The samples of the A6276EA-T arrived in less than a week.

If you need chips, request the 76, they have those in stock.

scorpia
02-19-2008, 03:46 AM
Ok,

my maxim samples finally arrived today. im hoping to build up a grinch over the next week or so and do some testing. just need to organise some thing to test with :).

oh and the samples are MAXIM max 6969ANG+ and MAX6979ANG.

i had a quick look and they at least looked like they have the right pinout so ill do some testing and see what happens

peter

derekhessman
02-19-2008, 08:16 PM
OK, I built my Grinch using the 76's and it is working perfectly. The 76 is definately a good substitute.

I'm now the proud owner of 64 channels of blinky flashy.


Well, the 79's I requested came in the mail today. They must be back in stock. Does anyone know if you mix and match the 76's and the 79's? ie if you used 4 79's and one went bad could you put in a 76 and have then play nice together?

synnie
04-04-2008, 08:25 PM
Just asking if anyone has finished there projects with the Allegro substitutes and which ones work ok? Hopefully we can get them here in Australia too

scorpia
04-05-2008, 03:17 AM
Well the maxim chips i tried have worked fine once i added a limiting resistor to the bottom of the board. so it will work fine if you mod a grinch and should work as expected in a ledtricks without any mods.

Peter

PS. the 79 chip has a led safety turnoff after 1 sec of no activity so that may cause some issues if not allowed for.

kenjinx
09-14-2008, 11:01 PM
The chips they sent worked fine.

dadams14
09-18-2008, 07:37 AM
from others text, I am using the correct ics
I have rechecked almost everything, the only thing I did not do was ground all pins 18 - 25 on the parallel port cable. I connected pin 18 and 25 together and grounded those. The instructions were not quite clear on that. (pin 18 - 25)
I don't know if this will keep my grinch from working.
EPP in bios - done
chips in correctly - done
both leds are on grinch and ssr
using simple 595 on vixen
any help is appreciated in advance
Dennis
PS ....Oh it's September, look at the time