I am using two LTC3614 and one LTC3617 in my application. You can see the block diagram of the circuit in the attachment as setup1 file. I am using a 5VDC external power supply for my circuit. In this setup when I switch on the 5VDC supply, the output voltage waveform of 3617 is shown in Figure1 in the attachment.
When I try to solve this problem, I tried several things and I noticed a situation; the setup for this circuit is shown in setup2 file. In this setup when I switch on the 3 power supplies simultaneously I got an output waveform same as the setup1. But, when i follow the following steps:
-Switch on 5VDC power supply,
-Switch on 1V5DC power supply,
-RUN is pulled down to GND
The output voltage of the 3617 is 0.7VDC.
-Switch on 3V3 RUN power supply
The output voltage of the 3617 is 0.75VDC.
Is there a voltage opening sequence for 3617? Why, the output voltage of the 3617 reaches to 1V in the setup1?
Is there a minimum load requirement for 3617? Why, although the run pin tied the ground the output voltage of the 3617 is 0.7VDC in setup2?
Could you help me with the root cause of the problems I mentioned above?
Thank you and best regards,