ADA4780 does not start up from a limited power supply.
Circuit is powered by 6W dcdc wich goes OVC cycling after power up.Pulling SD bar pin low during power up cures OVC. However the ampappeared to be in SC condition, i.e. 300 mV on TFL pin. Even more,nothing is connected to the output besides 2k resistor to inverting input.In order to turn damn thing on reset controller in not enough. I have to cycle SD barthus 2 states plus cycle ON bar afterwards thus 2 more states on power up.Summing up 4 states. Is not it too much for a mere opamp?Looking at posts it seems to be a common problem with the part in question.Please come up with the circuit needed and post it at product folder.P.S. My sincere congratulations to the digital age egghead designed an OpAmpthan needs 4 states Mealy machine to start up upon application of power.
I've just checked support people reply time up to few month.Thanks ADI you have made my day.
Hi baa, can you provide more information on your circuit? Specifically, what are the supply voltages you are using? I don't see Vee connected to anything but that may just be a misleading detail in your schematic. The amplifier is not intended to require 4 states to power it up, so I agree it's doing something unexpected. Please advise power supply configuration so that we can investigate.
Also, just to be clear, is this an actual bench circuit problem, or are you running a simulation?
Applications Mgr., High Voltage Amplifiers
SD bar should go high before ON bar.