Hello
I am designing a bosst converter from 5V to 12V. I use a datasheet schema (page9).
Without load, output is 12V, but when i have a load ( 1kohm or less), the output step down and my current source limit activate.
I don 't understand why. Can you help me?
thanks
Best regards,
Céline
What type of input power supply are you using? Could you monitor the 5V input voltage while you are loading the part and see if it drops.
Regards,
Marc
I am using a hewlett Packard supply with 5v/1A. To protect my design the current limit is set 600mA.
When I load the LMR64010, I can monitor 5v . 5V input drops to 2.5V and the current limitation of my supply activates.
The load is a 150ohm (12V/150=80ma).
Thanks for your help.
oscilloscope display:
yellow: input voltage
green: output voltage
in the middle, it's the moment with load.
Hi
i try to remove capacitor 220pf called Cf. I load with 80mA,I obtain 12v output but with a lot of noise.
But the device consume 180mA.
It mean's i have a very small efficiency.
However, i think this capacitor is required to filter the feedback, and i don't understand why with Cf, the device input drops.
I try to load with 40mA.
input voltage 5v --> 170mA input
then i increase input to 7v and i return to 5V. At this moment the device consume 110mA.
why? it's like the device was in start mode without succeeding to stop this mode.
celine
Could you turn the input current limit on the supply all the way up to 1 amp. I just want to try and eliminate that as a potential problem.
Also can you send me the bill of materials that you used for this part, and a picture of your layout. This will let me look for other potential problems.
Thanks,
hi,
Sorry, but i was in holidays!
I try to change the inductance. It was a 400mA dc max, with a 1A dc max, it works.
thank you for your help!