Specification Of Ic's Used; Hef 4511 B Bcd To 7-Segment Latch Decoder - Philips PM2517E Service Manual

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3.4.
S P E C I F I C A T I O N O F I C ' S U S E D I N T H E P M 2 5 1 7
3.4.'1. HEF 4511 B BCD to 7-segment latch decodet
The HEF 451 1 is a BCD to 7-segment latch/decoder/driver with four address inputs (A0-A3). an active
LOW latch enable input (ELJ, an active LOW ripple blanking inputTIET, an acrive LOW lamp test input
( l T L ) , a n d e v e n a c t i v e H I G H n - p - n b i p o l a r s e g m e n t o u t p u t s ( O a t o O g ) .
When E-L is LOW, the state of the segment outputs (Oa to Oo) is dete-rmined by the data on AO to 43.
When Et goes H lGH, the last data present on AO ro A3 are siored in the latches and the segment outputs
remain stable. When i=il is LOW, all the segment outputs are HIGH independent of all other input conditions.
W i t h I T L H I G H . a L O W o n I B f o r c e s a l l s e g m e n t o u t p u r s L O W . T h e i n p u t s I T L a n d I B d o n o t e f f e c t t h e l a t c h
c i r c u i t .
I
c
b
o
I
I
G N D
I
V
Fis. 27.
address (data) inputs)
latch enable input {active LOW)
r i p p l e b l a n k i n g i n p u t ( a c t i v e L O W )
lamp test input (active LOW)
segment outputs
L-
Fis.28.
V s s ( - 8 . 5 V )
A O
A 3
I B
I l L
A 2
P I N N I N G
AO to A3
' B
m
H E F 4 5 I 1
V s s ( - 8 . 5 V )
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