Sixth iteration of Apple iPhone, announced on September 12, 2012. Repair of this device is similar to the previous models, requiring screwdrivers and prying tools. Available as GSM or CDMA / 16, 32, or 64 GB / Black or White.

3109 Questions View all

vbat vs vccmain different//?

i want to know different between vccmain and vbat power rails. i know both same voltage. who create vccmain ? pm ic or q1403??

Answered! View the answer I have this problem too

Is this a good question?

Score 0
Add a comment
Black Friday
Broken doesn't stand a chance.

1 Answer

Chosen Solution

Q1403 is a power MOSFET (P-Channel enhancement mode MOSFET). This kind of FET is used for high-side switching, allowing PP_VCC_MAIN to charge the battery or not.

So in essence:

  • PP5V0_USB gets converted to ~4.25V by the internal Buck converter in Tigris to create PP_VCC_MAIN.
  • CHG_ACT_DIO will go low (0V) when it detects something in the charge port.
  • VCC_MAIN & BATT_VCC are connected together via Q1403 and battery charging occurs.
  • When the battery is fully charged, CHG_ACT_DIO goes high and cuts the connection between PP_VCC_MAIN & PP_BATT_VCC.

What's not entirely clear is what the battery lines in Tigris (A1-D1) do because we don't know what the internal logic is. Are they switched internally to output at VDD_MAIN (A2-D2) when no charging occurs or does BATT_VCC go though the body diode of the MOSFET to supply VCC_MAIN? Given that there is very little Forward Voltage drop measured across the body diode, I believe it is the former and not the latter. Only the Apple engineers know for sure.

EDIT

I've edited this answer so that it is a little clearer and more importantly, there is a big unknown because no one knows what the internal logic of TIGRIS is. This answer is my "reading" of the schematic. Only the Apple engineers know for certain what goes on inside TIGRIS.

Was this answer helpful?

Score 1
Add a comment

Add your answer

Mohammed Irfan will be eternally grateful.
View Statistics:

Past 24 Hours: 0

Past 7 Days: 2

Past 30 Days: 14

All Time: 58