Other Parts Discussed in Thread: LDC2114, LDC0851
So I need some guidance in tweaking the frequencies and inductance to achieve above mentioned targets.
Thanks !
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So I need some guidance in tweaking the frequencies and inductance to achieve above mentioned targets.
Thanks !
Hi Kristin,
Thanks a lot for reply., I will evaluate LDC2114 also
In my application I just need to detect direction of rotation and count the number of rotation, and I have to make sure I don't miss any rotation.
Yes Speed will keep varying,
5-4mm will be the distance between coil and Metal Body.
Also that whole dial has a diameter of 12mm so my sensor col can only be 5-6mm
HI Kristin,
Thanks a lot for your reply.
Interestingly that's the IC from which we started our research :D
Yes you are right, the dial is slow moving, so LDC2114 is out of question then.
I can't change the shape of dial, this is made by different vendor and is standard in metering industry
But I am very curious what is your idea, can you please tell me ?
About LDC Calculator, how can I design coil for LDC0851? I need coil to be within 5-6mm diameter, maybe I have to use Solenoid with soft Iron Core ?
Thanks, Cheers !
Regards
Vidit Katlana
Hi Vidit,
The LDC0851 requires the two sensor coils to be very closely matched for proper operation. For this reason, I strongly recommend using PCB coils instead of wire-wound coils. The PCB coils will be matched much better. You should be able to design PCB coils that suit your 5-6mm size requirement. The major limiting factor for sensor size is the minimum inductance. If the coil's inductance is too low, the LDC devices will not be able to drive the sensor with enough current to keep it properly oscillating.
The LDC0851 is essentially an inductance comparator. It will output a logic high or low depending on which coil (either the reference or the sensor) has a lower inductance. If it were possible to change the target shape, you could use two metal sectors of different arc lengths to create a unique output signature. The coils would be placed next to each other so that the rotating dial could cover them equally. For example, if the output stayed high when the plastic part of the dial was over the coils, the output could be briefly pulled low by the small metal sector, then pulled high by a gap between the metal sectors, then pulled low for a longer duration as the larger metal sector rotated past the coils, and finally returning high as the plastic once again covers the coils. You could detect the direction of rotation using the order of the logic low pulses (either short->long or long->short) and could use either pulse duration to detect each individual rotation.
It may be possible to achieve a similar effect by varying the shape of the coils, but as I mentioned above the LDC0851 requires very closely matched coils, so this would be very challenging.
Regards,
HI Kristin,
LDC0851 is having challenges in switching on distance, power consumption, form factor etc.
My question is, is there any other alternative than LDC ?
Anything that solves the purpose, I am happy with it.