# AD2S1210 LOS and DOS threshold calculation

Hi Experts!.

It`d be nice if someone explains me how can I calculate LOS and DOS thresholds for AD2S1210 which is working in next conditions.
1. Resolver executed using EXC output from  AD2S1210 at 5 KHz which is buffered and amplified by OPA so the resulting execution voltage is 3.8 Vp-p  (+- 1.9 V).
2. Coefficient of the  resolver 0.575 at selected execution frequency.
3. Resolver outputs directly connected to AD2S1210 inputs SIN/SINL COS/COSL. As it`s written in datasheet AD2S1210 introduces Vref/2 offset to its inputs.
(I confirm this, if disconnect resolver from ether AD2S1210 SIN/SINL or COS/COSL inputs this voltage can be measured by multi-meter on `em in relation to AGND. In my case 1.21Vdc. )

So as I suppose input voltages have next configuration: Max amplitude  3.8Vp-p * 0,575 = 2.18 Vp-p which are offset by 1.21V. At 90 degrees sin voltage has 1.21V-(2.18/2)V =  0.12V min value and 1.21V + (2.18/2)V = 2.3V max value and the same for cos input voltage but at 0 degrees.
Min amplitude of sin signal since sin(0) = 0 just equals Vref/2 voltage and min amplitude of cos signal at 90 degrees is the same Vref/2.

Also, in my case system dosen`t rotate all the time, most of time it stays steady at some position.

Thanks for any help!

P.S. Input signals a little violate datasheet at minimum voltage 0.15V but now it`s working fine excepts faults detection which I`m trying to configure right.

Information was extended.
[edited by: Gans at 2:17 PM (GMT 0) on 9 Sep 2019]

### Top Replies

• Gans,

The Loss of Signal threshold is programmable by writing to register 0x88 as described on page 16 of the datasheet.   The code is determined by computing your desired threshold divided by the weight of the LSB (38mV) so for 2.00V (1.976V to be exact) threshold you would write 52 decimal (0x34h).    THis is described in the register map section.

Sean