LM2611 regulator don't starts

Hi, There is a bit inrush current on start-up, can you set the current limit on your supply to 1A instead of 500mA and try again.
regards
John

Thanks John,
This indeed was the cause to this problem.

Hi again,
Unfortunately I see now that the inrush current was not my only problem - now the regulator gets hot even though its load is only 10mA.
Please advice.

Hi, I quickly put a resistive load on the device of 300mA all ok, how are you applying the load?
regards
john

Hi John,
As you can see in the schematic i attached previously, there is a jumper JP11 that connects the regulator output to the load (became to be -5V power line). This load is made of four dual OpAmps that consumes total of 10mA (I measured the regulator output current and verified that it indeed drives only 10mA).
The other rail of the OpAmps uses +5V from the power supply but I disconnect it to prevent any other current consumption from the PS.
Now when i turn on the PS its current meter shows 210mA. So i came to the conclusion that 210-10 = 200mA must be consumed by the regulator itself. How come?

reg,

Shony

Hi Shony,

Can you show your overall schematic,how you are driving the Op amps including grounding.

regards

John

Hi John,

Attached the relevant pages of my design that includes the regulators and the OpAmps circuits.

regards,

Shony

plant-a.pdf

Hi Shony, Is the current all going into LM2611 or is that total system current, can you remove the load and split supply to measure the current on each regulator, if LM2611 is taking all the current it will be hot to touch and may be damaged.
cheers
John

Hi,
I indeed first split the regulators to isolated the current consumed by the LM2611 and its load. I also used a current meter between the LM2611 and its load to measure the current consumed by the load only - 10mA. This way I could calculate the current dissipated by the regulator and came to the conclusion that it is about 150mA - and it indeed get hot.
I have another identical board. The phenomenon is the same.

Obviously something cause the regulator to dissipate very high power. What can cause to such phenomenon?

Shony

Hi Shony

Can you probe the switch node. can you also remove the 1K load, you might need to change the inductors, current saturation is 70mA, also DCR is really high. Would you be able to change the inductors and diode to match the ones in figure 26 of DS.

regard John.

Hi John,

I tried everything, including replacing the inductors with very efficient ones and also replacing the diode with few different diodes, but unfortunately this didn't help - some of the diodes didn't succeed to start-up the regulator.

Finally the regulator burnt out.

I consider to replace this regulator with similar one in terms of packaging and configuration (not necessary identical). Can you recommend on such regulator?

Reg,

Shony 

Hi Shony,

I have an EVM configured as per figure 26 in the datasheet and it has no excessive IQ under your conditions, maybe as a starting point you should configure your board as figure 26 and work from there.

regards

John