Mosaic
Well-Known Member
For the boost converter to derive 5V from a Li ion batt, I am looking at fig 5.2 here:
http://www.farnell.com/datasheets/1787127.pdf
I note a large 47uF ceramic cap is suggested....but then they add 0.1 ohm to increase the ESR.
As alum polymer caps have much lower esr than 0.1ohm, I am leaning toward using a Nichicon PM series 470uF alum electrolytic instead to have a similar ESR.
http://nichicon-us.com/english/products/pdfs/e-pm.pdf
Also, to meet the spec. for the external NFET (section 5.2.2.1 in the first datasheet above) ...I have selected this one.
http://www.irf.com/product-info/datasheets/data/irlr6225pbf.pdf
Does the cap. selection and the Nfet selection seem reasonable?
I need to run some 4.5V minimum TPIC6B595 SIPO registers from the Li ion batt and drive some RGB LEDs as well.
http://www.farnell.com/datasheets/1787127.pdf
I note a large 47uF ceramic cap is suggested....but then they add 0.1 ohm to increase the ESR.
As alum polymer caps have much lower esr than 0.1ohm, I am leaning toward using a Nichicon PM series 470uF alum electrolytic instead to have a similar ESR.
http://nichicon-us.com/english/products/pdfs/e-pm.pdf
Also, to meet the spec. for the external NFET (section 5.2.2.1 in the first datasheet above) ...I have selected this one.
http://www.irf.com/product-info/datasheets/data/irlr6225pbf.pdf
Does the cap. selection and the Nfet selection seem reasonable?
I need to run some 4.5V minimum TPIC6B595 SIPO registers from the Li ion batt and drive some RGB LEDs as well.
