ADN8835 Design

Hi Hope ,

Thank you for reaching out.

Seeing your schematic I would have some suggestions. I am seeing that you will be using digital control, right? if the chopper amplifier1 will be unused, you may short the OUT1 pin to IN1N pin, then connect the IN1P to gnd (buffer configuration with input grounded). 

Next is, make sure that the enable pin is pulled high to operate. 

What is the OUT2 voltage when you saw that the SW is short to GND?

Take a look at the LDR and SFB vs. OUT2 so you will know that to expect on the output of the LDR and SFB.

See figures 37 to 39 on the datasheet.

Double check also the resistor values on the ILIM and VLIM as I was not able to check it for you. 

Best regards,

Noel

Appreciate for your great support

Yes, we had used the digital control, and we will try the soluution as your suugestion

We will communicate with you in coming future if more need

Hi Noel

Hi Noel

Hi Noel     

Sorry to disturb you

Would you please help check the below question and give us any advice
   1,   Please help check if you can share the original documents of Layout about ADN8835CP-EVALZ
         How to achieve single point grounding in the PCB design as below SCH design                                                                                        2，If the power supply is 5V, what to pay attention to in the design,and if the ADN8835 can used when the power supply is 5V without any risk                                                                                                                                                                                                                                                                                            Looking forwoard to your reply                                           

Hi Hope ,

No worries. I'll try to help you the best way I can. On your questions:

1. I am giving you this link to the ADN8835 user guide evaluation board. You can check on page 9 how the PCB layout was routed.

https://www.analog.com/media/en/technical-documentation/user-guides/ADN8835CP-EVALZ-UG-951.pdf

The signals gnd and the power gnd are separated throughout and meet at a single point on pin 7 and 8 of J6. 

Top Layer:

2nd Layer:

3rd Layer:

Bottom Layer:

2. There is no problem in using the ADN8835 with 5V input. it can guarantee operation up to VIN = 5.5V. You may want to check the voltage rating of the TEC that you are going to use. Just in case it cannot handle 5V, you can always set the VLIM (ILIM for current) limit to protect your TEC.

Thank you.

Regards,

Noel

Hi Noel                                                                                                                                      If the power supply of ADN8835 change to 3.3v from 5.5V . Do we need to change the software about digital thermal PID to meet the power supply change

Hi Hope ,

I think changing the VIN while in operation and not changing the PID loop can cause some indications of not optimized loop. I suggest to have it tuned on both VIN levels then use each value depending on the VIN.

Thanks,

Noel