Other Parts Discussed in Thread: CSD18509Q5B
Hi,
We are currently using LM5175 Buck-Boost converter as a DC-DC converter from 10V-17V to Vout of 12V with a maximum current of 10A.
On our application the converter is working in Buck mode only - from 13V-17V to Vout of 12V (It originally designed to be also Boot but not anymore..)
Some of our users are connecting a DC-AC converters to the output of the LM5715 and its not working.
After testing few different DC-AC converters we saw that when connecting the DC-AC to a 12V PS, it has an inrush current of about 100A for about 150uSec.
Currently we have 4mOhm sense resistor that connected between "CS" and "CSG" pins, and a SS capacitor of 200nF.
We tried to replace the sense resistor to 3mOhm and some of the DC-AC converters started to work. So we tried to place 2mOhm sense resistor and some more DC-AC started to work. Finally we placed 1mOhm resistor and almost all of the DC-AC converters started to work (Vin was 14.5V).
BTW:
1. We have a SW current limit protection of 10A.
2. We are using the DCM with Hiccup enabled MODE.
3. RT/SYNC resistor is 130Kohm - its about 200Khz
4. HDRV1 and LDRV1 MOSFETs P/N is CSD18509Q5B, and the inductor value is 2.6uH.
5. We are not using the average input/output current limiting (it is shorted to GND).
So I have the following questions:
1. Is it OK to use 1mOhm sense resistor? will it effect the stability?
2. If we will connect the average input/output current limiting to the input, will it effect this issue? (will the converter cut the inrush current?)
Thanks :)
