diff pirelli/chg-circuit @ 388:b99663e66660

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
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--- a/pirelli/chg-circuit	Wed Mar 23 21:20:26 2022 +0000
+++ b/pirelli/chg-circuit	Wed Mar 23 21:55:57 2022 +0000
@@ -71,3 +71,19 @@
 on L7, microvia to L8 at (5514,741).  On L8 the microvia lies in the polygon
 that connects the drain output of the P-MOSFET to the anode of the Schottky
 diode, matching TI's reference charging circuit.
+
+Now let's look for the main charging current path after the Schottky diode.  On
+L8 the cathode pad is a rectange, center at (5470,621), no visible microvia
+hole.  On L7 in this spot there is a polygon separate from GND pour, and in
+this polygon 4 inner via holes are visible, arranged in a neat 2x2 pattern.
+The upper left of these 4 vias is at (5514,538).  On L1 there is a row of 4
+microvias from (5485,513) to (5542,511) - let's see if they fall into the
+polygon on L2 that connects to the 4 inner vias for the charging current - they
+do!  The polygon on L1 with these 4 stitching microvias is where the charging
+current comes to L1 - and lo and behold, on L1 we have a series resistor marked
+"R200" whose other side goes directly to the positive rail on the physically
+nearby battery connector!
+
+On L6 there is another connection to the 4-inner-vias charging current path,
+possibly for the purpose of bringing this net to Iota VCCS - but the trace gets
+lost in the grind-down damage.