The output voltage of the pin cp-out of the 36 pin of the ad9956 chip is 0, which leads to the low vibration frequency of the VCO. The output voltage of the pin cp-out of the 36 pin shoule be 3.3v,However, the chip can be programmed and work. The working voltage of the charge pump is 3.3v, which is no problem.So I can't find where the problem is.
Just to check, what is the value of your CP_Rset? The output current of the charge pump is programmed by this resistor.
Thanks for your reply,
This resistor is 2.7K,I remember that the current of CP_out equals 1.55 Divide by the resistor.And the most current of CP_out is 4mA.In the progrom,I give a Multiplier factor which is 8.
Thank you for confirming the value of the resistor on the CP_Rset. Is it possible to share your schematic?