SN74LS244: Logic forum

Hi Dylan,

Thanks a lot for your very prompt reply. This is exactly the device I was looking for.

Kindly allow me one additional question as follows:

Previously, TI used to publish regularly a so-called "TTL Data Book". This book used to contain a brief device description, pin diagram, and truth table. It was not a complete datasheet but it was a wonderful reference book to look for devices for selected functions and properties. I know this because I have worked for TI in Freising/Germany as an application engineer for some years in the early 80ies.  

Such books helped a lot to search for TTL devices with dedicated functions. Just like I had this question about an equivalent device for SN74LS244.

I know that these days paper books are not published anymore, but can I find such information (i.e. a list of TTL devices with short functional descriptions) somewhere on the TI Web page, please?

Thanks for your help in advance.

Best regards

Shyam Gupta

Hi Dylan,

Sorry, but I was too optimistic in my confirmation to your suggestion to use SN74LV541AT as eqivalent to SN74LS244.

Actually, SN74LV541AT and SN74LS244 are not quite equivalent!!

Reason: SN74LS244 has two 4-bit buffers/drivers which can be enabled/disabled separately thus the SN74LS244 can functions as 2 to 1 4-bit bus multiplexer. The SN74LV541AT on the other hand has single 8-bit buffer/driver. Both OE1 and OE2 enable/disable all 8-bits at the same time. Thus, unfortunately it cannot be used as a 2 to 1 4-bit bus multiplexer as in the case of SN74LS244.

May I request you to kindly suggest any other equivalent device which has all inputs and all outputs on the opposite side of the package, please.

And, this is exactly the reason I was asking for something like TTL databook service on paper or on Web-site. If available, I could easily look for such primitive information myself and would not be wasting  your valuable time.

But anyway kindly help me, please.

Thanks and best regards

Shyam Gupta 

Well, your first question was for an octal buffer, not for a multiplexer.

The search function shows that the only 8-bit buffers are 74xx241, 74xx244, and 74xx541. Actual multiplexers like the 74xx157, 74xx3257, TSxxx or TMUXxxx have the same pinout problem.

Apparently, you cannot avoid the more complex routing.

The last databook was the Digital Logic Pocket Data Book from 2007.

HI Clemens,

Thanks for your reply.

Meanwhile, I found SN74AC11244 which has exactly the same functinality as SN74LS244 (i.e. I can multiplex two 4-bit busses) and has inputs and outputs on the opposite side.

It is a bigger package (24 pins) but that should be no problem. I can make a simple to route PCB with this device. I only hope that this device is still in production and thus available.

Thanks once again for your help.

Best regards

Shyam Gupta