# HG changeset patch # User Mychaela Falconia # Date 1648065968 0 # Node ID 8d19e61d202f925731058064566b44607bd8391a # Parent 79e512a21e029cbea4c8bd986d2b72a6f9e4cdfa pirelli/chg-circuit: found VBUS, VCHG and ICTL diff -r 79e512a21e02 -r 8d19e61d202f pirelli/chg-circuit --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/pirelli/chg-circuit Wed Mar 23 20:06:08 2022 +0000 @@ -0,0 +1,62 @@ +VBUS from USB connector on L1: microvia at (5679,1177). On L2 a transition is +made to two directly adjacent inner vias at (5689,1157) and (5709,1186). On L5 +another transition is made to a new pair of inner vias at (5565,1089) and +(5569,1125). On L7 yet another transition to what appears to be a pair of +microvias to L8, guessing center coordinates at (5546,1077) and (5546,1108). +On L8 this VBUS supply passes through a series component marked "H" before going +to the rest of the circuit. After passing through this "H" series component, +the fat power trace goes to a polygon on L8 whose bottom y coord is 1041, top y +coord 834. This polygon contains pads for 3 caps (other sides remain to be +traced) and a microvia at (5592,1034). The left x coord boundary of the polygon +is at 5515 where the cap is, or 5474 to the left and up from the cap. The right +x coord boundary is at 5627. + +The big polygon identified in the previous paragraph feeds VBUS power to a 6-pin +component that might be the power P-MOSFET for charging. The 4 pins that could +constitute the drain output of this big MOSFET land on another polygon which in +turns feeds to a 2-pin component: it might be the Schottky diode. + +Out of the 3 caps connected to what seems to be VCHG (VBUS passed through the +"H" component), the lower little seems to go to GND, but where does the upper +little go? Apparent microvia from L8 to L7 at (5709,940), on L7 there seems to +be a trace going back to L8 at (5663,858) and an inner via at (5675,965). It +looks like ICTL net! + +Now let's trace the other side of the left bigger cap from MOSFET VCHG input. +L8 pad center is at (5469,950), on L7 that spot is solid GND fill - consistent +with the natural expectation that this cap goes to GND. + +Let's trace the presumed ICTL net and see if it really is what it seems to be. +Inner via at (5675,965) - found it on L2. Microvia to L1 at (2923,1163), on L1 +it goes to Iota ball D6 - it is indeed ICTL! + +Now let's trace the branch from VCHG (VBUS after "H") polygon that starts with +L8-L7 microvia at (5592,1034). On L7 it goes to an inner via at (5618,1019) - +but no connections are seen on any other layer! + +Let's try tracing VBUS connection to CP2102. There appears to be an L8-L7 +microvia at (5349,1392). On L7 this spot falls on a fat power trace made out +of a polygon. This polygon has two visible via holes at (5390,1271) and +(5631,1250). It also has spots that may contain hidden microvias back to L8: +candidate spots (5459,1177), (5460,1059), (5635,1226). Looking on L8, we see +that the L7 via hole at (5631,1250) is likely a microvia back to L8, connecting +to the VBUS-after-"H" fat trace, whereas (5390,1271) is probably an inner via. +The other 3 spots found from L7 are either false leads or contain microvias to +the same power trace on L8, as that's where the coordinates fall. + +Looking for (5390,1271) inner via on other layers: found it on L2, connects to +L2-L1 microvia at (5371,1298). Also on L4: a thick power trace to another inner +via at (4031,1549). Let's go back to L2-L1 microvia at (5371,1298): on L1 it +is a test point and nothing more. Now let's look for the inner via at +(4031,1549): on L2 it connects to L2-L1 microvia at (4000,1563). On L1 this +microvia falls into the pad of some 2-pad component to GND, and also goes to +another microvia at (4011,1435). On the populated pic, the 2-pad component +appears to be a diode, with the cathode connected to the power net (VCHG?) and +with the anode to GND. + +Continuing the trace from L1-L2 microvia at (4011,1435): on L2 there is a power +trace to another microvia at (3003,1363). On L1 it goes to Iota ball A5 - it +is VCHG. + +The via hole on L7 at (5631,1250) appears to be an inner via after all: let's +look for it on other layers. Couldn't find any connections.