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Lsli06.4up - 06-1 06-1 Conversion To Logic Levels Problem Convert a voltage or other quantity to a logic value The electrical characteristics of a

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Unformatted text preview: 06-1 06-1 Conversion To Logic Levels Problem: Convert a voltage or other quantity to a logic value. The electrical characteristics of a and 1 vary with logic family. (Don’t assume ground is a and 5 V is a 1 .) Will describe (plain) TTL and CMOS. 06-1 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli06. 06-1 06-2 06-2 Plain TTL Logic Levels Introduction There are many varieties of TTL. Each has different electrical charac- teristics. Material here is for “plain” TTL. V CC A B AB 4 k Ohm 1.6 k Ohm 130 Ohm 1 k Ohm 06-2 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli06. 06-2 06-3 06-3 V CC A B AB 4 k Ohm 1.6 k Ohm 130 Ohm 1 k Ohm Input to gate is a transistor emitter. With at input, current will be flowing out of input-transistor emit- ter. A is at 0 . 4 V with current flowing to ground. This can be provided by a 250 Ω resistor to ground. With 1 at input, input transistor turned off, no current flows. A 1 must then be greater than 4 . 5 V. This can be provided by a 50 kΩ resistor to V cc or 5 V. 06-3 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli06. 06-3 06-4 06-4 Example A circuit having a push button should have a 1 output when the button is pressed and a output at other times. The circuit below is all that’s needed. V CC A B AB 4 k Ohm 1.6 k Ohm 130 Ohm 1 k Ohm 06-4 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli06. 06-4 06-5 06-5 CMOS Logic Levels A B AB V DD CMOS circuits use pairs of complementary transistors. Input is applied to gate of transistors. Almost no direct current flows through gate. Input of 0 V for and V DD for 1 . 06-5 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli06. 06-5 06-6 06-6 Error Error is the difference between an ideal (or correct) value and an actual value. • Several different types of error can be measured....
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This note was uploaded on 11/28/2011 for the course EE 4770 taught by Professor Staff during the Fall '99 term at LSU.

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Lsli06.4up - 06-1 06-1 Conversion To Logic Levels Problem Convert a voltage or other quantity to a logic value The electrical characteristics of a

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