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参数资料
| 型号： | 74LS47 |
| 厂商： | Fairchild Semiconductor Corporation |
| 英文描述： | BCD to 7-Segment Decoder/Driver with Open-Collector Outputs |
| 中文描述： | BCD码到7段解码器/驱动器，集电极开路输出 |
| 文件页数： | 2/6页 |
| 文件大小： | 67K |
| 代理商： | 74LS47 |
www.fairchildsemi.com
2
D
M
74LS47
Truth Table
Note 2: BI/RBO is wire-AND logic serving as blanking input (BI) and/or ripple-blanking output (RBO). The blanking out (BI) must be open or held at a HIGH
level when output functions 0 through 15 are desired, and ripple-blanking input (RBI) must be open or at a HIGH level if blanking or a decimal 0 is not
desired. X
= input may be HIGH or LOW.
Note 3: When a LOW level is applied to the blanking input (forced condition) all segment outputs go to a HIGH level regardless of the state of any other input
condition.
Note 4: When ripple-blanking input (RBI) and inputs A0, A1, A2 and A3 are LOW level, with the lamp test input at HIGH level, all segment outputs go to a
HIGH level and the ripple-blanking output (RBO) goes to a LOW level (response condition).
Note 5: When the blanking input/ripple-blanking output (BI/RBO) is OPEN or held at a HIGH level, and a LOW level is applied to lamp test input, all segment
outputs go to a LOW level.
Functional Description
The DM74LS47 decodes the input data in the pattern indi-
cated in the Truth Table and the segment identification
illustration. If the input data is decimal zero, a LOW signal
applied to the RBI blanks the display and causes a multi-
digit display. For example, by grounding the RBI of the
highest order decoder and connecting its BI/RBO to RBI of
the next lowest order decoder, etc., leading zeros will be
suppressed. Similarly, by grounding RBI of the lowest order
decoder and connecting its BI/RBO to RBI of the next high-
est order decoder, etc., trailing zeros will be suppressed.
Leading and trailing zeros can be suppressed simulta-
neously by using external gates, i.e.: by driving RBI of a
intermediate decoder from an OR gate whose inputs are
BI/RBO of the next highest and lowest order decoders. BI/
RBO also serves as an unconditional blanking input. The
internal NAND gate that generates the RBO signal has a
resistive pull-up, as opposed to a totem pole, and thus BI/
RBO can be forced LOW by external means, using wired-
collector logic. A LOW signal thus applied to BI/RBO turns
off all segment outputs. This blanking feature can be used
to control display intensity by varying the duty cycle of the
blanking signal. A LOW signal applied to LT turns on all
segment outputs, provided that BI/RBO is not forced LOW.
Decimal
Inputs
Outputs
or
Note
Function
LT
RBI
A3
A2
A1
A0
BI/RBO
a
b
c
d
e
f
g
0
H
L
H
L
LLL
LL
H
(Note 2)
1
H
X
L
H
L
H
(Note 2)
2H
X
L
H
L
H
L
H
L
H
L
3
H
X
L
H
HHL
L
H
L
4H
X
L
H
L
H
L
H
L
5
H
X
L
H
L
HHL
H
L
H
L
6
H
X
L
H
L
H
LL
LLL
7
H
X
L
H
HHL
L
H
8
H
X
H
L
H
L
LLL
9
H
X
H
L
H
L
LL
H
LL
10
H
X
H
L
H
L
H
L
H
L
11
H
X
H
L
H
HL
L
H
HL
12
H
X
H
L
H
L
H
L
13
H
X
H
L
HHL
H
L
H
L
14
H
X
HHH
L
H
L
15
H
X
H
HHH
BI
XXX
L
H
(Note 3)
RBI
H
L
H
HHH
(Note 4)
LT
L
X
H
L
LLL
(Note 5)
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 74LS47 WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| 74LS47DE4 | 制造商:TI 制造商全称:Texas Instruments 功能描述:BCD-TO-SEVEN-SEGMENT DECODERS/DRIVERS |
| 74LS47PC | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Texas Instruments 功能描述: |
| 74LS48 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:BCD to 7-Segment Decoder |
| 74LS48PC | 制造商:Texas Instruments 功能描述: |
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