In this iPhone 6 schematic, why is the VCC line tied into the SW and VP pins? My confusion stems from thinking SW means switching as in a boost or buck circuit but because it's directly linked to VP which I'm guessing is the input for the ic it's throwing me off. I believe this link is the Datasheet for the ic https://www.cirrus.com/en/pubs/proDatasheet/CS35L01-03_F1.pdf
In this iPhone 6 schematic, why is the VCC line tied into the SW and VP pins?
Notice that the incoming
PP_BATT_VCC supply does not connect directly to the
SW pins. Inductor
L1604 is effectively between the
My confusion stems from thinking SW means switching as in a boost or buck circuit but because it's directly linked to VP which I'm guessing is the input for the ic it's throwing me off.
As I said, the
SW pins are not directly connected to the
VP pins :-) However there is some switching involved - see below.
I believe this link is the Datasheet for the ic https://www.cirrus.com/en/pubs/proDatasheet/CS35L01-03_F1.pdf
I don't think so. :-) That one is a much simpler audio IC. The specific IC in that schematic (CS35L19B-XWER) seems not to be generally available. However Cirrus Logic do sell another audio IC with similar power connections - the CS35L32 (datasheet).
That IC (in common with some other audio ICs) can operate at a lower voltage than the (higher) voltage used to drive the loudspeaker(s) (and, on the CS35L32, also used to drive the LEDs). Therefore the IC contains a built-in boost converter which can generate a higher voltage than its supply voltage. That requires an external inductor, and that is what
Look at the CS35L32 datasheet linked above and you will see it is a complex IC, but section 4 describes the power supplies, speaker amplifier and the boost converter which uses the
SW pins. Looking at the external power connections and external inductor in the schematic extract you included, I believe that your questions about the CS35L19
VP pins are answered by the relevant part of the CS35L32 datasheet.
Here is a diagram from the CS35L32 datasheet, showing the equivalent of the
L1604 inductor (here marked LBST) between the
So unless someone finds a CS32L19B datasheet, I hope that should be enough information to answer your questions.