Problem with AD9954 DDS as it stops giving signal after drawing 1A
时间：04-09
整理：3721RD
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AD9954 is a 400MHZ DDS that works with 3.3V as DVDD-IO and 1.8V as DVDD and
1.8V as AVDD.so it uses 3 suply.
when I worked with its dev kit,suddenly it draws 1A! current and stop giving signals ,at final I desoldered the IC from board and tested with DVM ,I found out that DVDD-IO ,DVDD,DGND was shorted(short circuit),but AGND and AGND are ok and no short circuit!
what is the cause of the problem? this happened when I turned off the supply(they turned off simultanously.
1.8V as AVDD.so it uses 3 suply.
when I worked with its dev kit,suddenly it draws 1A! current and stop giving signals ,at final I desoldered the IC from board and tested with DVM ,I found out that DVDD-IO ,DVDD,DGND was shorted(short circuit),but AGND and AGND are ok and no short circuit!
what is the cause of the problem? this happened when I turned off the supply(they turned off simultanously.
There is no sequence requirement for supply voltages on AD9954.
Is possible to be just a defective IC, if AVDD is no higher than 2V which will destroy the circuit.
I used 2 TPS76801 as LDOs for powering DDS 1.8V(AVDD,DVDD)