From: drowe67 <drowe67@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Thu, 18 Sep 2014 20:37:14 +0000 (+0000)
Subject: adc spike caps
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=40844b69d807a43b6e33455ee82f83bdca803f7b;p=freetel-svn-tracking.git

adc spike caps

git-svn-id: https://svn.code.sf.net/p/freetel/code@1844 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/smartmic/SM1000-C/Change-Log-C.txt b/smartmic/SM1000-C/Change-Log-C.txt
index 238b4c97..794ce6ab 100644
--- a/smartmic/SM1000-C/Change-Log-C.txt
+++ b/smartmic/SM1000-C/Change-Log-C.txt
@@ -289,7 +289,12 @@ Status:	Researching effect on TPS54329E SW PS chip.	RGB 09/15/14
     + supply easy in US or Asutalia
     + Just a suggestion at this stage, part of the enclosure discussion
     Status:	No Action	RGB 09/15/14
-   
+
+58. Nice tactile feeling switch for PTT
+    (like power switch, put perhaps not locking?)
+
+59. 1nF on ADC1 and ADC2 inputs close to uC.  While debgugging noise I found big spikes and ringing when the ADCs sample.  I think it's the inability of the op-amps to drive high frequencies.  These caps removed the ringing, but made no apparant difference to the noise.  However I think they are useful as a precaution to reduce the general level of noise on the board.
+
 Questions:
 1.  SM1000 designed to be operated with 6-16V power supply. Would should recommend 9-15V. Should we recommend PS? Many will operate at 13.8V(rig supply). Do we risk ground loops, etc. using rig supply?
 2.  Should C37, C39, C40 be 50V? Or, only caps connected to VIN?