ELM405 Datasheet, PDF (1/10 Pages) ELM Electronics – Rotary Decoder - 3 wire 4x Interface

ELM405
Rotary Decoder - 3 wire 4x Interface
Description
The ELM405 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 ELM405, as this is all
performed within the integrated circuit. After
debouncing the encoder signals, the ELM405
determines the direction of shaft rotation, and then
generates the appropriate outputs. The polarity of
the clock output can be changed at any time to
accommodate different needs.
The ELM405 provides 4x decoding of a rotary
encoder signal. If your application requires 2x
decoding, please see the ELM404 (it is identical to
the ELM405 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
• Startup delay timer
• High current drive outputs
Connection Diagram
PDIP and SOIC
(top view)
VDD 1
A2
B3
Clk 4
Invert
8 VSS
7 CS
6 Clk
5 U/D
Block Diagram
VDD
A
2
VDD
B
3
Rotary
Encoder
Debounce
Circuit
Debounce
Circuit
Direction
Decoding
Output
Logic
Clk 4
Invert
7 CS
6 Clk
5 U/D
ELM405DSA
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