some questions of “Control TEC with ADN8830”

it's the schematic.

there are some questions.

1、the schematic is right?

2、the voltage of VREF(pin7)can't reach 2.5V,only about 1V.【VCC=5V】

3、4 MOSFETs can be turned on only three.

4、the voltage of pin12 Doesn’t equal the  Twenty times the second pin and the fourth pin of the voltage difference +1.5V。

...........

what should I do to solve these problem.

thanks to answer.

For a Chinese, English is really hard to ask questions

  • 0
    •  Analog Employees 
    on Apr 28, 2015 4:41 AM

    What is the value of potentiometer RP2 and what is the VLIM pin voltage? VLIM should be set below 1.5V therefore RP2 should be smaller than 0.6k ohm, which means VREF is sourcing a noticeable amount of current. Either way the part can't function properly. I would suggest connecting VREF to ground through a 100k ohm resistor to leave voltage limit wide open and see if VREF voltage is back to 2.5V.

    The connection of the FETs looks right, I wonder if the P1, N1, P2, N2 pins have output when you saw the FET not turned ON?


  • Thanks  for your answer . I have revised some circuits, but the results are not satisfactory.

    I have  connected VLIM to ground directly.

    I have connected VREF to ground through a 100k ohm resistor.

    But VREF=about 0.5V.

    I have other questions.

    1、pin25(SYNCIN) should connect to ground?

    2、the MOSFET should use FDW2520C? if  not,will affect the voltage of VREF?

    Looking forward to your reply. thank you

  • 0
    •  Analog Employees 
    on Apr 30, 2015 12:52 AM

    Apologies for the typo. I was suggesting "connecting VLIM to ground through a 100k ohm resistor". VREF shouldn't be short to ground.

    SYNCIN pin should be tied to ground if external clock is not needed. In this case the switching frequency is set by FREQ pin and R9 in your schematic.

    VREF is an independent circuit block and will not be affected by MOSFET selection.

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:00 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin