What is the power up sequence of AD6633 core and I/O?

Document created by analog-archivist Employee on Feb 23, 2016
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the program and other configuration are correct, but there is no current
output, should it be the power up sequence problem?


The power up sequence is very important. If you power up VI/O 3.3V only and get
1A current, it proved there is EOS issue on your board, then power up sequence
is very important. Please make sure 3.3V and 1.8V are directly coming from one
signal 5V, then use big capacitor (470uF) on 3.3V, small capacitor on 47uF on
1.8V, to make Vcore power up before VIO.
You can also use another simple sequencer IC ADM1085 to control the enable pin
of LDO (need LDO with enable or shut down such as ADP3335, please note ADP3335
only on VIO).
Power up 1.8V Core 20ms before 3.3V I/O. Your AD6633 has no current if you
power up Vcore and VIO together. If  you power up 3.3V I/O only, current may be
bigger than 1A.