Hello. I am using LM43603. I have used the tools provided by Texas Instruments to calculate the value of the external components. This is the arrangement:
The problem I have is that I hear a very small noise coming from the inductor. I have tried changing the value of RT resistor, to change the frequency. I have tried with RT=OPEN, RT=205k and RT= 22k. The current the regulator is delivering is very low (5mA). There is a uC and a blinking led in the circuit (besides another devices). I can hear the noise increasing when the led is on and decreasing when is off.
The noise is very small and only can be heared if you put your ear on the coil. The output voltage of the buck regulator is ok. I have attached the oscilloscope´s probe and there is no oscillation on the output. All seems to be ok at the output of the regulator.
The LM43603 is feeding a power-path/battery charger and this power-path/battery charger is feeding a buck-boost regulator to get 3V3. So the power chain is:
12V ----> LM43603 ----> POWERPATH/BATTERYCHARGER ----> BUCK/BOOST ----> 3V3
I do not know if this arrangement could be a problem or not. And I don´t know if this audible noise coming from the coil is normal. Could somebody help?
Thank you in advance!
