low signal from AD5420


I put together a CN0270 (HART) circuit, but the Iout AD5420   is 30mv, and should be 400mV.

On the HARTout  pin (AD5400), the modulation amplitude is normal 450 mV.

I am enabled REXT in the data register AD5420. Iout set 4 mA.

from modem signal is coming normally.

Why is there a large attenuation of the amplitude?   (the HART modem doesn't see the signal)

add modem signal is coming
[edited by: AndreyCobra at 8:13 AM (GMT 0) on 25 May 2020]