From 75c012d460b0c92c46d3fc29633034157a2468b1 Mon Sep 17 00:00:00 2001 From: emard Date: Thu, 21 Feb 2019 16:11:10 +0100 Subject: [PATCH] manual update powering ft231x --- doc/MANUAL.md | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/doc/MANUAL.md b/doc/MANUAL.md index fdc59d8..b1722cb 100644 --- a/doc/MANUAL.md +++ b/doc/MANUAL.md @@ -83,10 +83,17 @@ Plug US1 into PC or USB charger and board should power up. Initial voltage rise at USB 5V line will trigger board powering up and holding the power. -USB-serial chip FT231X will always be powered from 5V USB -on PCB v1.7. The board has switching voltage regulators +On PCB v1.7, USB-serial chip FT231X will always be powered from 5V USB. +The board has switching voltage regulators which can be turned off to reduce power consumption. +On PCB v2.0 and later, USB-serial chip FT231X will be directly +powered only from US1. If board is powered from US2, there is diode +preventing 5V to FT231X power pin, but FT231X will still be weakly +back-powered from its other pins connected with rest of the board +and it will appear as some load. For most practical cases, we +are lucky that FT231X appears as high-z when not directly powered. + Green LED D18 behaviour is the "Power LED". Green LED ON will keep board powered up. By factory default, when USB-serial chip is enumerated by PC, Green LED will turn ON.