Allegro ICs Sub??????

[kenjinx]

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]

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]

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]

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]

can you use these ones A6279ELW-T

[prof]

The A6279ELW-T is a SOIC surface mount package not the DIP version.

[kostyun]

I also have the Maxim MAX6969, which appears to be compatabile.

[kenjinx]

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]

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]

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.