IC ISSUE

Thread Starter

atulsonpal

Joined Jul 25, 2020
3
HI

I HAVE 1 PCB WHERE THIS IS NO CD 74HC244E IS THERE AN I HAVE TO REPLACE THIS IC AS THIS HAS COME FAULT IN IT
NOW I CANNOT FIND THIS IS IN MUMBAI I CAN FIND THIS IC WHICH IS SN 7HHC244N IS THIS THE SAME IC OR IS THERE IS ANY DIFFERENCE

PLEASE IF SOMEONE CAN HELP ME ON THIS

CHECK BOTH THE ICS PHOTOS
 

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OBW0549

Joined Mar 2, 2015
3,509
They are the same IC, at least functionally. There might be some slight differences in their characteristics but I wouldn't expect anything that would make a significant difference. I think you can use one in place of the other with no fear of problems.
 

Thread Starter

atulsonpal

Joined Jul 25, 2020
3
They are the same IC, at least functionally. There might be some slight differences in their characteristics but I wouldn't expect anything that would make a significant difference. I think you can use one in place of the other with no fear of problems.
Thanks a lot for your reply.
 

dl324

Joined Mar 30, 2015
11,282
This is just another example of how manufacturers are needlessly complicating things.

They're functionally and electrically the same.
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CD is the prefix used by RCA for their CD4xxx line of CMOS that operated from 5-20V. For some unknown reason, Harris thought it would be helpful to combine the CD and 74HC prefixes. It's dumb because the voltage range for those families are different, but they're not the only ones employing faulty, misguided logic. Samsung has a line of HCT parts where they chose to insert the LS labeling. I had to search far and wide to determine whether the outputs were CMOS or TTL (they're CMOS with TTL compatible input levels, so the TTL designation is inappropriate).

74HC was originally a high speed CMOS family that was function and pin equivalent to 74xxx logic, but had a wider operating voltage than TTL (2-6V for HC and 4.75-5.25V for 74xxx). Though the inputs conformed to CMOS thresholds and the outputs were also only CMOS compatible.

Various manufacturers have been using alphabet soup in their part numbers, so 74HC244, SN74HC244, CD74HC244 are essentially the same part. TI manufacturers parts with both numbers you gave. SN was their prefix for TTL and now CMOS; they also have military grade parts that were marked SN54xxx.

The N suffix on SN74HC244N indicates PDIP package. The E suffix on CD74HC244E denotes lead free in PDIP. TI took the easy way out because the latter part was originally from Harris, which TI acquired. In their infinite wisdom, they chose to have multiple parts with similar part numbers; likely so they wouldn't confuse Harris customers.

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Thanks for not continuing to use all caps. That's considered shouting.
 
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