Hello forum,
I am designing the TPS61028 into one of our High Definition Earthworks Microphones, and I need to achieve the lowest possible noise performance possible. I chose this part because it can regulate down to 0.9V so it can be used with any battery, also because of its high efficiency and high PWM frequency.
I only need about 10 mA of output drive at 5.5V, and I tie the PS to Vbat as I need the PWM frequency to stay out of the audio range.
TI in its datasheets says that values in the range of 2uH to 22 uH are preferable for optimum performance, but when I use the inductor selection equation and based on the small ripple Id I have in this application, I get a required value in excess of 500 uH.
My question here relates to my inductor selection and is 2 fold:
By using a 6.8uH inductor in a 10 mA output drive design at 5.5V output, am I generating a lot of ripple current and hence making the design susceptible to EMI and excess noise.
How high of an inductor value can I use with the TPS61028 and still maintain stability with such a design.
Thank you so much.
