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부품번호 | ELM415 기능 |
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기능 | Up/Down Interface | ||
제조업체 | ELM | ||
로고 | |||
전체 5 페이지수
ELM415
Up/Down Interface
Description
Many modern control circuits use the value from
a digital counter to directly determine a setting or
position. Manipulating this value under computer
control is not difficult, but when one has to interface
with a human operator, several other factors must be
considered. Human interfaces often require that the
circuit respond to changes in a setting – up or down,
left or right, clockwise or counterclockwise. These
controls need a simple interface, which the ELM415
provides.
This 8 pin integrated circuit contains all the
timing and logic that is necessary to interface two
pushbuttons to most counter type interfaces. It reads
the position of the switches and translates that into
an appropriate signal for a counter to either
increment or decrement, which in turn controls the
output variable. Logic to filter out contact bounce, to
sense when both keys are pressed simultaneously,
to invert the count output, and to provide continuous
pulses if an input pushbutton stays pressed are all
included.
Applications
• Digital audio potentiometer controls
• Variable voltage or temperature circuits
• Motor positioning controls
• Single-stepping control circuits
• Reset circuits
Features
• Low power CMOS design – typically 1mA at 5V
• Wide supply range – 3.0 to 5.5 volt operation
• Fully debounced switch inputs
• Internal pullup resistors provided
• Protection from simultaneous key presses
• High current drive outputs – up to 25 mA
• User selectable automatic repeat function
• Selectable Count output polarity
Connection Diagram
PDIP and SOIC
(top view)
VDD 1
Up/Down 2
Count 3
Invert 4
8 VSS
7 DownSw
6 UpSw
5 Repeat
Block Diagram
VDD
7
DownSw
VDD
6
UpSw
Debounce
Circuit
Debounce
Circuit
Logic
reset
Latch
set
2 Up/Down
Pulse
Generator
Output
Control
3 Count
Repeat 5
4 Invert
ELM415DSA
Elm Electronics – Circuits for the Hobbyist
< http://www.elmelectronics.com/ >
1 of 5
Free Datasheet http://www.datasheet4u.com/
ELM415
Example Applications
Figure 1 shows the ELM415 used to interface two
pushbutton switches to an ELM310 stepper motor
controller, so that the motor position can be manually
controlled. For simplicity, the stepper motor and its
drive transistors are not shown in the diagram. Notice
that pin 5 has been tied to VDD in order to enable the
automatic repeat function, allowing the motor to move
‘continuously’ if a button is held down. Also, because
there are internal pullup resistors, the two pushbuttons
have been connected directly to the inputs without
further support circuitry.
Using the ELM310 to control a stepper motor has
many advantages – low cost, low power, and ease of
use, for example. The disadvantage, however, is that
the integrated circuit is capable of responding very
quickly to input signals. This could result in multiple
steps of the motor, and perceived erratic motor
operation, if the input were not ‘debounced’ by a circuit
such as the ELM415.
A
+5V
18
To winding
+5V 2 7 B drive circuits
54
3 6C
Clockwise
63
72
+5V
81
4 5D
Counter
clockwise
Figure 1. Controlling a stepper motor
The circuit of Figure 2 is very similar to the one
above, but it uses an Analog Devices AD5220 Digital
Potentiometer as the controlled device. The up and
down buttons are used to ‘move’ the wiper between
the two ends (pins 3 and 6). As shown, when stepped
in the Up direction, the AD5220 moves the wiper
towards the pin 3 end of the pot, while Down moves it
towards pin 6.
The AD5220 expects to have a Count signal that
is normally low, pulsing to a high level in order to
change the resistance, so pin 4 is connected to a low
(VSS) level, as shown. Some devices, such as the
Maxim MAX5160, require an inverted Count output,
which can be provided by simply tying pin 4 to VDD
instead of VSS.
Up
Down
VDD
5
6
7
8
4
3
2
VDD
1
VDD
18
2 AD5220 7
36
45
Figure 2. Controlling a digital potentiometer
ELM415DSA
Elm Electronics – Circuits for the Hobbyist
< http://www.elmelectronics.com/ >
4 of 5
Free Datasheet http://www.datasheet4u.com/
4페이지 | |||
구 성 | 총 5 페이지수 | ||
다운로드 | [ ELM415.PDF 데이터시트 ] |
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부품번호 | 상세설명 및 기능 | 제조사 |
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DataSheet.kr | 2020 | 연락처 | 링크모음 | 검색 | 사이트맵 |