74247.md

74247: BCD to 7-segment decoder, active low

• Type: decoder
• DIP: 16-pin
• Input: 4-bit BCD
• Output: 7-Segment active low

Description

This chip decodes a 4-bit BCD to an active low seven segment display. The BCD is input through pins D1 to D4 where D4 is the highest bit.

The chip provides zero-blanking through pin RBI, blanking through pin BI, and a lamp test through pin LT (all active low).

Inputs and outputs

Label	Description	Signal
LT	lamp test	active low
RBI	zero blanking	active low
BL	blanking	active low
D1	bit 1 of BCD	active high
D2	bit 2 of BCD	active high
D3	bit 3 of BCD	active high
D4	bit 4 of BCD	active high
Ya	segment a	active low
Yb	segment b	active low
Yc	segment c	active low
Yd	segment d	active low
Ye	segment e	active low
Yf	segment f	active low
Yg	segment g	active low
Yh	segment h	active low

Function table

LT	RBI	BL	D4	D3	D2	D1	Ya	Yb	Yc	Yd	Ye	Yf	Yg	Display
H	L	L	L	L	L	L	H	H	H	H	H	H	H	Blank
H	H	H	L	L	L	L	L	L	L	L	L	L	H	0
H	X	H	L	L	L	H	H	L	L	H	H	H	H	1
H	X	H	L	L	H	L	L	L	H	L	L	H	L	2
H	X	H	L	L	H	H	L	L	L	L	H	H	L	3
H	X	H	L	H	L	L	H	L	L	H	H	L	L	4
H	X	H	L	H	L	H	L	H	L	L	H	L	L	5
H	X	H	L	H	H	L	L	H	L	L	L	L	L	6
H	X	H	L	H	H	H	L	L	L	H	H	H	H	7
H	X	H	H	L	L	L	L	L	L	L	L	L	L	8
H	X	H	H	L	L	H	L	L	L	L	H	L	L	9
H	X	H	H	L	H	L	H	H	H	L	L	H	L
H	X	H	H	L	H	H	H	H	L	L	H	H	L
H	X	H	H	H	L	L	H	L	H	H	H	L	L
H	X	H	H	H	L	H	L	H	H	L	H	L	L
H	X	H	H	H	H	L	H	H	H	L	L	L	L
H	X	H	H	H	H	H	H	H	H	H	H	H	H
X	X	L	X	X	X	X	H	H	H	H	H	H	H	Blank
L	X	H	X	X	X	X	L	L	L	L	L	L	L	8

• H: HIGH voltage level
• L: LOW voltage level
• X: don't care

Pin layout

TODO

	Pin	Pin
D2	1	16	VCC
D3	2	15	Qf
LT	3	14	Qg
BL	4	13	Qa
RBI	5	12	Qb
D4	6	11	Qc
D1	7	10	Qd
GND	8	9	Qe

Datasheets

TODO