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This is from an iPhone 6. I'm having a hard time understanding how q1701 controls the "handshake" to Tristar_pin to allow charging. (Diagram says "pin for handshake" next to C1704 at top right.)

I don't see anything controlling the gate of q1701 either. Am I right to assume current flow that I've traced in red?

enter image description here

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    \$\begingroup\$ Please post a clearer png, this is unreadable \$\endgroup\$ – Voltage Spike Sep 16 '16 at 23:00
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    \$\begingroup\$ @laptop2d It's a screen shot from my phone. Looks clear until I upload it. Idk why \$\endgroup\$ – ohmmy Sep 16 '16 at 23:04
  • \$\begingroup\$ Probably cropping... \$\endgroup\$ – Voltage Spike Sep 16 '16 at 23:11
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    \$\begingroup\$ If I show entire circuit it looks even worse. Is there a way to post it better from just a screen shot from phone? \$\endgroup\$ – ohmmy Sep 16 '16 at 23:21
  • \$\begingroup\$ "q1401 controls the "handshake" to Tristar_pin to allow charging" - says who? "I don't see anything controlling the gate of q1401" - I don't even see a q1401... \$\endgroup\$ – Bruce Abbott Sep 17 '16 at 2:25
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If "Tristar pin" (which appears to be what it says on diagram) is taken high then the P Channel MOSFET (which the diagram shows that it is ) is turned on as it is P Channel (according to diagram) and then has gate low and source high. A greater issue is that IF the pin is tristated then the FET state is undefined - but arguably that's not a problem as it does or doesn't connect the output to a tristated pin. If the pin is low then the FET is off and the output is high impedance (which may be termed tri-stated depending on their nomenclature).

The FET MAY also be one of

CSD68822F4 TLV70518YFPR TPS62698YFDR TPS826745SIPT

IF the chart here means what it appears to mean.

enter image description here

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