FreeCalypso > hg > freecalypso-reveng
comparison pirelli/chg-circuit @ 386:8d19e61d202f
pirelli/chg-circuit: found VBUS, VCHG and ICTL
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Wed, 23 Mar 2022 20:06:08 +0000 |
| parents | |
| children | f190b78c3b6a |
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| 385:79e512a21e02 | 386:8d19e61d202f |
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| 1 VBUS from USB connector on L1: microvia at (5679,1177). On L2 a transition is | |
| 2 made to two directly adjacent inner vias at (5689,1157) and (5709,1186). On L5 | |
| 3 another transition is made to a new pair of inner vias at (5565,1089) and | |
| 4 (5569,1125). On L7 yet another transition to what appears to be a pair of | |
| 5 microvias to L8, guessing center coordinates at (5546,1077) and (5546,1108). | |
| 6 On L8 this VBUS supply passes through a series component marked "H" before going | |
| 7 to the rest of the circuit. After passing through this "H" series component, | |
| 8 the fat power trace goes to a polygon on L8 whose bottom y coord is 1041, top y | |
| 9 coord 834. This polygon contains pads for 3 caps (other sides remain to be | |
| 10 traced) and a microvia at (5592,1034). The left x coord boundary of the polygon | |
| 11 is at 5515 where the cap is, or 5474 to the left and up from the cap. The right | |
| 12 x coord boundary is at 5627. | |
| 13 | |
| 14 The big polygon identified in the previous paragraph feeds VBUS power to a 6-pin | |
| 15 component that might be the power P-MOSFET for charging. The 4 pins that could | |
| 16 constitute the drain output of this big MOSFET land on another polygon which in | |
| 17 turns feeds to a 2-pin component: it might be the Schottky diode. | |
| 18 | |
| 19 Out of the 3 caps connected to what seems to be VCHG (VBUS passed through the | |
| 20 "H" component), the lower little seems to go to GND, but where does the upper | |
| 21 little go? Apparent microvia from L8 to L7 at (5709,940), on L7 there seems to | |
| 22 be a trace going back to L8 at (5663,858) and an inner via at (5675,965). It | |
| 23 looks like ICTL net! | |
| 24 | |
| 25 Now let's trace the other side of the left bigger cap from MOSFET VCHG input. | |
| 26 L8 pad center is at (5469,950), on L7 that spot is solid GND fill - consistent | |
| 27 with the natural expectation that this cap goes to GND. | |
| 28 | |
| 29 Let's trace the presumed ICTL net and see if it really is what it seems to be. | |
| 30 Inner via at (5675,965) - found it on L2. Microvia to L1 at (2923,1163), on L1 | |
| 31 it goes to Iota ball D6 - it is indeed ICTL! | |
| 32 | |
| 33 Now let's trace the branch from VCHG (VBUS after "H") polygon that starts with | |
| 34 L8-L7 microvia at (5592,1034). On L7 it goes to an inner via at (5618,1019) - | |
| 35 but no connections are seen on any other layer! | |
| 36 | |
| 37 Let's try tracing VBUS connection to CP2102. There appears to be an L8-L7 | |
| 38 microvia at (5349,1392). On L7 this spot falls on a fat power trace made out | |
| 39 of a polygon. This polygon has two visible via holes at (5390,1271) and | |
| 40 (5631,1250). It also has spots that may contain hidden microvias back to L8: | |
| 41 candidate spots (5459,1177), (5460,1059), (5635,1226). Looking on L8, we see | |
| 42 that the L7 via hole at (5631,1250) is likely a microvia back to L8, connecting | |
| 43 to the VBUS-after-"H" fat trace, whereas (5390,1271) is probably an inner via. | |
| 44 The other 3 spots found from L7 are either false leads or contain microvias to | |
| 45 the same power trace on L8, as that's where the coordinates fall. | |
| 46 | |
| 47 Looking for (5390,1271) inner via on other layers: found it on L2, connects to | |
| 48 L2-L1 microvia at (5371,1298). Also on L4: a thick power trace to another inner | |
| 49 via at (4031,1549). Let's go back to L2-L1 microvia at (5371,1298): on L1 it | |
| 50 is a test point and nothing more. Now let's look for the inner via at | |
| 51 (4031,1549): on L2 it connects to L2-L1 microvia at (4000,1563). On L1 this | |
| 52 microvia falls into the pad of some 2-pad component to GND, and also goes to | |
| 53 another microvia at (4011,1435). On the populated pic, the 2-pad component | |
| 54 appears to be a diode, with the cathode connected to the power net (VCHG?) and | |
| 55 with the anode to GND. | |
| 56 | |
| 57 Continuing the trace from L1-L2 microvia at (4011,1435): on L2 there is a power | |
| 58 trace to another microvia at (3003,1363). On L1 it goes to Iota ball A5 - it | |
| 59 is VCHG. | |
| 60 | |
| 61 The via hole on L7 at (5631,1250) appears to be an inner via after all: let's | |
| 62 look for it on other layers. Couldn't find any connections. |