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comparison pirelli/chg-circuit @ 388:b99663e66660

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pirelli/chg-circuit: traced the current path to the battery
author Mychaela Falconia <falcon@freecalypso.org>
date Wed, 23 Mar 2022 21:55:57 +0000
parents f190b78c3b6a
children
comparison
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387:f190b78c3b6a 388:b99663e66660
69 another inner via at (5548,1198). Looking for the new via: found it on L5, goes 69 another inner via at (5548,1198). Looking for the new via: found it on L5, goes
70 to another via at (5593,717). Looking for the new via at (5593,717): found it 70 to another via at (5593,717). Looking for the new via at (5593,717): found it
71 on L7, microvia to L8 at (5514,741). On L8 the microvia lies in the polygon 71 on L7, microvia to L8 at (5514,741). On L8 the microvia lies in the polygon
72 that connects the drain output of the P-MOSFET to the anode of the Schottky 72 that connects the drain output of the P-MOSFET to the anode of the Schottky
73 diode, matching TI's reference charging circuit. 73 diode, matching TI's reference charging circuit.
74
75 Now let's look for the main charging current path after the Schottky diode. On
76 L8 the cathode pad is a rectange, center at (5470,621), no visible microvia
77 hole. On L7 in this spot there is a polygon separate from GND pour, and in
78 this polygon 4 inner via holes are visible, arranged in a neat 2x2 pattern.
79 The upper left of these 4 vias is at (5514,538). On L1 there is a row of 4
80 microvias from (5485,513) to (5542,511) - let's see if they fall into the
81 polygon on L2 that connects to the 4 inner vias for the charging current - they
82 do! The polygon on L1 with these 4 stitching microvias is where the charging
83 current comes to L1 - and lo and behold, on L1 we have a series resistor marked
84 "R200" whose other side goes directly to the positive rail on the physically
85 nearby battery connector!
86
87 On L6 there is another connection to the 4-inner-vias charging current path,
88 possibly for the purpose of bringing this net to Iota VCCS - but the trace gets
89 lost in the grind-down damage.