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annotate pirelli/chg-circuit @ 387:f190b78c3b6a

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pirelli/chg-circuit: found PCHG and the precharge circuit
author Mychaela Falconia <falcon@freecalypso.org>
date Wed, 23 Mar 2022 21:20:26 +0000
parents 8d19e61d202f
children b99663e66660
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
386
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
1 VBUS from USB connector on L1: microvia at (5679,1177). On L2 a transition is
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
2 made to two directly adjacent inner vias at (5689,1157) and (5709,1186). On L5
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
3 another transition is made to a new pair of inner vias at (5565,1089) and
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
4 (5569,1125). On L7 yet another transition to what appears to be a pair of
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
5 microvias to L8, guessing center coordinates at (5546,1077) and (5546,1108).
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
6 On L8 this VBUS supply passes through a series component marked "H" before going
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
7 to the rest of the circuit. After passing through this "H" series component,
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
8 the fat power trace goes to a polygon on L8 whose bottom y coord is 1041, top y
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
9 coord 834. This polygon contains pads for 3 caps (other sides remain to be
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
10 traced) and a microvia at (5592,1034). The left x coord boundary of the polygon
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
11 is at 5515 where the cap is, or 5474 to the left and up from the cap. The right
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
12 x coord boundary is at 5627.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
13
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
14 The big polygon identified in the previous paragraph feeds VBUS power to a 6-pin
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
15 component that might be the power P-MOSFET for charging. The 4 pins that could
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
16 constitute the drain output of this big MOSFET land on another polygon which in
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
17 turns feeds to a 2-pin component: it might be the Schottky diode.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
18
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
19 Out of the 3 caps connected to what seems to be VCHG (VBUS passed through the
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
20 "H" component), the lower little seems to go to GND, but where does the upper
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
21 little go? Apparent microvia from L8 to L7 at (5709,940), on L7 there seems to
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
22 be a trace going back to L8 at (5663,858) and an inner via at (5675,965). It
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
23 looks like ICTL net!
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
24
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
25 Now let's trace the other side of the left bigger cap from MOSFET VCHG input.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
26 L8 pad center is at (5469,950), on L7 that spot is solid GND fill - consistent
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
27 with the natural expectation that this cap goes to GND.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
28
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
29 Let's trace the presumed ICTL net and see if it really is what it seems to be.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
30 Inner via at (5675,965) - found it on L2. Microvia to L1 at (2923,1163), on L1
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
31 it goes to Iota ball D6 - it is indeed ICTL!
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
32
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
33 Now let's trace the branch from VCHG (VBUS after "H") polygon that starts with
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
34 L8-L7 microvia at (5592,1034). On L7 it goes to an inner via at (5618,1019) -
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
35 but no connections are seen on any other layer!
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
36
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
37 Let's try tracing VBUS connection to CP2102. There appears to be an L8-L7
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
38 microvia at (5349,1392). On L7 this spot falls on a fat power trace made out
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
39 of a polygon. This polygon has two visible via holes at (5390,1271) and
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
40 (5631,1250). It also has spots that may contain hidden microvias back to L8:
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
41 candidate spots (5459,1177), (5460,1059), (5635,1226). Looking on L8, we see
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
42 that the L7 via hole at (5631,1250) is likely a microvia back to L8, connecting
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
43 to the VBUS-after-"H" fat trace, whereas (5390,1271) is probably an inner via.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
44 The other 3 spots found from L7 are either false leads or contain microvias to
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
45 the same power trace on L8, as that's where the coordinates fall.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
46
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
47 Looking for (5390,1271) inner via on other layers: found it on L2, connects to
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
48 L2-L1 microvia at (5371,1298). Also on L4: a thick power trace to another inner
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
49 via at (4031,1549). Let's go back to L2-L1 microvia at (5371,1298): on L1 it
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
50 is a test point and nothing more. Now let's look for the inner via at
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
51 (4031,1549): on L2 it connects to L2-L1 microvia at (4000,1563). On L1 this
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
52 microvia falls into the pad of some 2-pad component to GND, and also goes to
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
53 another microvia at (4011,1435). On the populated pic, the 2-pad component
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
54 appears to be a diode, with the cathode connected to the power net (VCHG?) and
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
55 with the anode to GND.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
56
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
57 Continuing the trace from L1-L2 microvia at (4011,1435): on L2 there is a power
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
58 trace to another microvia at (3003,1363). On L1 it goes to Iota ball A5 - it
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
59 is VCHG.
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
60
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
61 The via hole on L7 at (5631,1250) appears to be an inner via after all: let's
8d19e61d202f pirelli/chg-circuit: found VBUS, VCHG and ICTL
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
62 look for it on other layers. Couldn't find any connections.
387
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
63
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
64 Let's try tracing PCHG (ball B5) from Iota: it goes through a 2-pad component
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
65 (probably the precharge current limiting resistor) centered at (2862,1443) and
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
66 then to a microvia at (2849,1378). On the populated pic, the 2-pad component
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
67 is indeed a black resistor, marked "470". Tracing the microvia from L1 at
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
68 (2849,1378): it goes to an inner via at (2865,1350). Found it on L4: goes to
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
69 another inner via at (5548,1198). Looking for the new via: found it on L5, goes
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
70 to another via at (5593,717). Looking for the new via at (5593,717): found it
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
71 on L7, microvia to L8 at (5514,741). On L8 the microvia lies in the polygon
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
72 that connects the drain output of the P-MOSFET to the anode of the Schottky
f190b78c3b6a pirelli/chg-circuit: found PCHG and the precharge circuit
Mychaela Falconia <falcon@freecalypso.org>
parents: 386
diff changeset
73 diode, matching TI's reference charging circuit.