This my 12V boost converter shematic and Vin voltage 6.6V to 8.4V. I use Texas Instruments LM3478 boost converter.
I calculated my capacitor value, resistor value, inductor value, switching frequency etc. with formulas in the datasheet. This shematic works fine when the 12 V current is bigger than 10 mA, but when current lower than 10 mA I hear a voice in inductance. I analyzed it with osciloscope and there is no gate drive.
- i can add a resistor to 12V like 2k2 ohm, but my V in batary, i dont want power loss.
- i think maybe, its capacitor esr problem.
- i can add a mosfet Vin and i can switch it when current bigger than 10mA. But i must change my firmware, shematic and pcb.
Also I have search this problem and i found discontinues mode. But i dont know how can i change my shematic.