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adn8834

Hi,

I had some problems testing the PCB board made by ADN8834 and hope you can help with it.

I made PCB boards based on the ADN8834CP-EVALZ evaluation board schematic,and with NTC, no TEC, Vvtec was at 1.25V. stating that LDR and SFB have no output and the truth.

But the actual Vout1 output varies according to the NTC resistance value, and the Vout2 is also changing.on the basis of

output

The LDR and SFB should have an output while I checked that the VDD input is 5V.

Vb

I don t understand why there is no output.Can you help me.

ADN8834CP-EVALZMy

Top Replies

  • Hi ,

    Thank you for reaching out. With your statements above, it can be said that the chopper amplifiers are working well. Am I right? With that, I agree that the LDR and SFB should have output with…

  • Hi ,

    Thank you for reaching out. With your statements above, it can be said that the chopper amplifiers are working well. Am I right? With that, I agree that the LDR and SFB should have output with respect to GND with the output relationship to OUT2 voltage defined by,


    I have reviewed your schematic and find it good. Let us go to some basic power-up checking.
    Have you tried checking the soldering of the IC if all the pins are connected to the pads? one way to check is that using a multimeter with the positive terminal probed to GND, probe all the other pins one by one with the negative terminal and it should give you a diode voltage drop. We can see then if the contact is good. Doesn't need to probe at the pin of the IC directly. You can use the trace that is directly connected to the said pins. If didn't give a diode voltage drop, it could be a poor contact. 
    Also, make sure the VLIM as the correct voltage, pulling it to low will put the part in shutdown mode. Also take a look at the EN/SY pin. It can be connected to VDD to make the part enable. 


    Thanks,

    Noel