LDC0851: LDC0851

Dear Luck,

We Wanted to test the proximity sensor output with 200mA load wirh proximity sensing Schematic Prints.pdfhence we did testing for the attached circuit.Its working but again found to be getting  bulky additional delays power consumption.

Please suggest , any other way to get the 200mA load driven at output.

Regards

Seema Joshi

Seema,

In your circuit, there will be an inversion between LDC0851 output and the signal labelled as O/P. Is this what you want ? If not then  you may want to eliminate the second NPN transistor.

You may want to plot the signals, LDC0851 output, NPN and PNP outputs to find which part of the circuit contributes maximum to the delay. By adjusting the bias resistors for NPN/PNP, you can tune the base and collector currents and optimize between delay and power consumption. You should also refer the d/s of the NPN/PNP used to find out the hFE (collector current/base current) and turn on times of the transistors themselves.

Regards

Nitesh

Dear Nitesh,

Sure! we want the 200mA current flow during sensor proximity  & normally we want no current. Also the requirement is to have 2 wires at out put one for load other for ground.

Accordingly the circuit is working.

Is there any other way to achieve the same in perview of reduction of components.

Shall we try making refernce & sense coil reverse & get the rquired output to avoid the one inversion stage??

Regards

Seema joshi

Seema,

If you are able to eliminate one additional NPN then it will definitely help reduce the solution size.

Lesser elements, would definitely help speed up the response, but you should check if you have biased the NPN's and PNP's optimally before making a change. Looking at intermediate waveform on an oscilloscope would help provide some clues.

In general you could simulate your circuit in a spice program . One such spice simulator is provided by TI and can be downloaded at http://www.ti.com/tool/tina-ti

. Several vendors provide spice models for the components, which can be imported in TINA.

One such e2e post  describes how to import a vendor provided spice model into TINA e2e.ti.com/.../452146

I was able to put together a sample circuit in TINA to demonstrate the concept. The attached circuit is able to achieve 200mA load current within few us of LDC output switching. Choice of transistors and biasing can be modified to suit the requirements.

Example_Output_Ckt.TSC

Regards

Nitesh

Dear NItesh,

Thanks for the support! One more issue mentioned bellow please check if you can suggest something .

Proximity sensor  non flush is working fine  with LDC0851  for proximity of 4mm as well as 5mm.

But if we try to assemble flush type proximity sensor  with stacked coil  when we try to cover coil with metal tube the proximity reduces to 2mm.

Please suggest if we try to cover periferry of the pcb coil with ferrite sheet ,will it solve the issue.?

Regards

Seema Joshi