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I have looked in the data sheets, as well as the TI article, but I am still unsure of the answer to this question:

What is the practical difference between a 7446 ("BCD to 7 segment decoder/driver with 30V open collector outputs"), a 7447 ("BCD to 7-segment decoder/driver with 15V open collector outputs"), a 7448 ("BCD to 7-segment decoder/driver with Internal Pullups"), and a 7449 ("BCD to 7-segment decoder/driver with open collector outputs").

To drive a normal 7 segment LED common-cathode display, can I use any of them? If not, what are they for?

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2 Answers 2

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'46 and '47 are for common-anode LEDs, whereas '48 and '49 are for common-cathode LEDs.

For the common-anode types, '46 allows a higher drive voltage than '47. For the common-cathode types, the difference between '48 and '49 is that '48 has "ripple-blanking input" (for suppressing leading zeroes), which the '49 has not.

There also are '246, '247 and '248 types that work like the above mentioned ones, but use a slightly different display pattern for "6" and "9" (namely with "tails").

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I have tried to list the differences. Refer this pdf for detailed information.

$$ \begin{array}{rcccc} \style{color:blue}{\textbf{}} & \style{color:blue}{\textbf{7446}} & \style{color:blue}{\textbf{7447}} & \style{color:blue}{\textbf{7448}} & \style{color:blue}{\textbf{7449}} \\ \style{color:blue}{\textbf{Active level}} & \mathrm{low} & \mathrm{low} & \mathrm{high} & \mathrm{high} \\ \style{color:blue}{\textbf{Output config}} & \mathrm{open\ collector} & \mathrm{open\ collector} & \mathrm{internal\ pullup} & \mathrm{open\ collector} \\ \style{color:blue}{\textbf{Max Voltage}} & 30V & 15V & 5.5V & 5.5V \\ \style{color:blue}{\textbf{Pins}} & 16 & 16 & 16 & 14 \\ \style{color:blue}{\textbf{Lamp Test}} & \mathrm{Yes} & \mathrm{Yes} & \mathrm{Yes} & \mathrm{No} \\ \style{color:blue}{\textbf{Blanking input}} & \mathrm{Ripple} & \mathrm{Ripple} & \mathrm{Ripple} & \mathrm{Direct} \\ \end{array}% $$

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