ELM407 Datasheet, PDF (1/10 Pages) ELM Electronics – Rotary Decoder - 3 wire 4x Interface

ELM407
Rotary Decoder - 3 wire 4x Interface
Description
The ELM407 is an 8 pin integrated circuit that is
used to convert the output from a rotary encoder into
three signals (chip select, clock and up/down) that
can be used to control various devices. The low
power CMOS technology used ensures that only a
very small current is required over the entire 2.0 to
5.5 volt operating range.
There is no need for external filtering or
debounce circuits with the ELM407, as this is all
performed within the integrated circuit. After
debouncing the encoder signals, the ELM407
determines the direction of shaft rotation, and then
generates the appropriate outputs. A write sequence
can also be generated if the Write Enable input is at
a high level when the outputs are generated.
The ELM407 provides 4x decoding of a rotary
encoder signal. If your application requires 2x
decoding, please see the ELM406 (it is identical to
the ELM407 in every respect, except that it provides
2x decoding).
Applications
• Digital audio potentiometer controls
• Variable voltage or temperature circuits
• Positioning controls
• Tuning circuits
Features
• Low power CMOS design
• Wide supply range – 2.0 to 5.5 volts
• Complete debouncing of the encoder inputs
• No external filtering needed
• 4x decoding
• Can generate a write sequence
• Startup delay timer
• High current drive outputs
Connection Diagram
PDIP and SOIC
(top view)
VDD 1
A2
B3
Write 4
Enable
8 VSS
7 CS
6 Clk
5 U/D
Block Diagram
VDD
A
Debounce
2
Circuit
Direction
Output
VDD
B
Decoding
Debounce
3
Circuit
Logic
Rotary
Encoder
Write 4
Enable
7 CS
6 Clk
5 U/D
ELM407DSA
Elm Electronics – Circuits for the Hobbyist
www.elmelectronics.com
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