ELM402 Datasheet, PDF (1/9 Pages) ELM Electronics – Rotary Decoder - 2 wire 2x Interface

ELM402
Rotary Decoder - 2 wire 2x Interface
Description
The ELM402 is an 8 pin integrated circuit that is
used to convert the signals from a rotary encoder
into a series of up and down output pulses. 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 ELM402, as this is all
performed within the integrated circuit. After
debouncing the encoder signals, the ELM402 then
determines the direction of shaft rotation, and
generates the appropriate pulses at the Up or Down
output pins. The duration of these pulses can be
selected for either 0.2 or 2.0 msec.
The ELM402 provides 2x decoding of a rotary
encoder signal. If your application requires 4x
decoding, please see the ELM403 (it is identical to
the ELM402 in every respect, except that it provides
4x 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
• 2x decoding
• Startup delay timer
• High current drive outputs
Connection Diagram
PDIP and SOIC
(top view)
VDD 1
A2
B3
Pulse 4
Width
8 VSS
7 Up
6 Down
5 Output
Invert
Block Diagram
VDD
A
Debounce
2
Circuit
VDD
B
Debounce
3
Circuit
Direction
Decoding
Output
Logic
7 Up
6 Down
Rotary
Encoder
Pulse 4
Width
5 Output
Invert
ELM402DSA
Elm Electronics – Circuits for the Hobbyist
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