LDC5072-Q1: Can't startup. Goes to bootloop

Kirill,

Is the Clc capacitor the resonant cap for the exciter coil?
If so, is it a single cap in parallel with the coil?

Regards,
John

2 capacitors parallel to exciter coil according to the datasheet

Kirill,

For the purposes of troubleshooting, let's try getting to a nominal exciter frequency of ~3.5MHz.
With that in mind, please try a ~3.8nF cap on each exciter pin to ground.

If possible, please look at the LCOUT pin with a high impedance probe.
One trick that can help with our inductive sensors is to put a leaded 1k resistor on the probe tip and use the other end of the resistor to probe the test point of interest. 
If possible, please post a scope capture to this thread, making sure the signal, time base and amplitude scales are visible.

Regards,
John

I setted up 2x3.5 nF (2 + 1.5 uF NP0). Here is scope of LCOUT via 1k.

Kirill,

Your middle plot shows the device is still in a FAULT condition, but the exciter frequency looks okay.
Are you using our LDC5072-Q1 EVM, or a custom PCB?
If it is the EVM, has it ben modified in any way?

Regards,
John

It's custom PCB without input RC filters. 

Kirill,

Is a target in place over the coils during the FAULT condition?
If so, what is the air gap?

Regards,
John

I tested with target, without target, with a small gap (0.6 mm) and greater (~1.5 mm).
This is a small linear sensor: 12x10 mm. IC on the top side of 2 mm PCB, coils on the bottom. It works with Renesas IPS2550, but I wanted to try the cheaper LDC5072 (also ordered 5071, it has less diagnostic). Placing input filters is quite difficult.
Actually IPS2550 is simple to use and has more settings and diagnostic. Do you plan to share test interface for diagnostic and maybe settings?

Kirill,

We do plan to release a GUI in the future, but we don't have a release date yet.

Could you share the complete PCB layout and the schematic of your PCB?
What is your device supply voltage?

Regards,
John

Supply is 3.3V. 

I can't share PCB because have NDA with customer. 
I will wait for debugger. And I will try 5071, and variation of the exciter and input coils inductance.