I need an encoder to put on a 22 mm motor that has a resolution under 200 counts per rev. Since the application is battery powered, power consumption is very important.

I am targeting a 5 mA current draw at 5 Vdc.

Does anyone have any suggestions??

RA

Find an encoder with a simple photo-transistor output and pulse the LED to read. Have the pullups for the photo-transistors on the same switched power as the led. Power on to read, power off to sleep between reads. Must read at least 2x faster than the maximum edge rate.

Jeffrey,

Thanks for the response. Unfortunately we can not change the interface circuitry to the encoder so we do not have the option of pulsing to read or any other type of sleep strategy.

RA

I read my original post and realized I did not specify the required output.

I need incremental, 2 channel (A, B) quadrature output.

Well, we won't light the led at 5ma, so optical is out, and the processing for axial magnetics are around 20ma which leaves them out. The AMT10x series by CUI has a typical draw of around 6ma, so that is close.

If you are willing to make/source your own ring magnet, consider using the A8775 ic from Asahi (Single 1.6 to 5.5V supply, <90microamps). These are slow devices (DC to 250Hz) so they are only appropriate if your rotation speed is slow.

Ralph,
We supply a BLDC motor range with a newly developed Magnetic encoder.
The new magnetic encoder converts the rotational movement of the motor coil into incremental square wave signals for rotational measurement. In doing so, 1024 impulses per revolution are generated.
As this is acting as a generator, effectively no power is required other than the power to activate the hall sensors.
Depending on the number you require we may be able to supply the encoder as a separate item.
Let me know.

Thank you for all that have responded. I guess I did not provide the RPM, which is 0-6000 rpm. I also am constrained to 160 counts per revolution exactly, so the binary output devices will not work for me directly, nor will the CUI capacitive technology without a special which they declined to do.

Are you up for building an encoder? If so, consider the A1230 from allegro as the sensing element. 3.5mA typical, Fast enough for 160 counts at 6000 RPM. You would need to have magnetic wheel made and circuit board to host the A1230. If you need sources for magnetic wheels or board design help for the A1230 let me know.

Also take a look at the MPS 160 from Timken - it has a 3mA low power mode (40mA normal operation). The low power mode is limited somewhat in speed.

With these narrow and exacting specifications, it sounds like you are going to be on a bit of a unicorn hunt. If your volume or budget will permit it, most manufacturers will consider a full custom. Another approach would be to use one of the analog output angular sensing hall devices into a small embedded processor and synthesizing the AquadB in software. 16 Khz logic output is quite slow and very reasonable with today's processors.