Dictionary of Electronic Terms
"A"
"B"
"C",
"D",
"E",
"F",
"G",
"H",
"I",
"J",
"K",
"L",
"M",
"N",
"O",
"P",
"Q",
"R",
"S",
"T",
"U",
"V",
"W",
"X",
"Y",
"Z"
BCD to Seven Segment Decoder IC
Seven Segment Decoder
7447 IC Schematic. BCD to 7-segment display driver.
Also refer to LED Display Manufacturers.
4-bit BCD to 7-bit LED driver IC [functional schematic].
7-Segment LED schematic
Note how the output letters of the integrated circuit [Output A] match with the Diode letters in the 7-Segment LED above. Each IC output corresponds to a particular input [diode] of the seven segment display.
The Lamp Test input pin on the IC simply just turns all the LEDs on at the same time. While the Blanking pin forces all the LEDs to turn off.
7447 IC 7 Segment Decoder True Table
7447 True Table Notes:
1. BI/RBO is wire-OR logic serving as blanking input (BI) and/or ripple-blanking output (RBO). The blanking
input must be open or held at a high logic level when output functions 0 through 15 are desired, and ripple-blanking
input (RBI) must be open or at a high logic level during the decimal 0 output. X = input may be high
or low.
2. When a low logic level is applied to the blanking input (forced condition) all segment outputs go to a low logic
level regardless of the state of any other input condition.
3. When ripple-blanking input (RBI) is at a low logic level, lamp test input is at high logic level and A = B = C = D
= low logic level, all segment outputs go to a low logic level and the ripple-blanking output goes to a low logic
level (response condition).
4. When blanking input/ripple-blanking output is open or held at a high logic level, and a low logic level is
applied to lamp test input, all segment outputs go to a high logic level.
How to convert between BCD and Decimal and Binary.
Similar devices:
5446; BCD-to-seven segment decoder/driver (30 volt, open collector output)
5447; BCD-to-seven segment decoder/driver (15 volt, open collector output) [Covered here]
5448; BCD-to-seven segment decoder/driver
5449; BCD-to-seven segment decoder/driver (5.5 volt, open collector output)
For additional internal IC schematics, also see the pages on;
BCD Decoder ICs or BCD Encoder ICs.
