From 9b6573780f663c8ec688148ed8a554e72b93d948 Mon Sep 17 00:00:00 2001 From: emard Date: Thu, 21 Feb 2019 16:45:18 +0100 Subject: [PATCH] manual: cleanup of 5V power mode description --- doc/MANUAL.md | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/doc/MANUAL.md b/doc/MANUAL.md index 443c1d1..1323560 100644 --- a/doc/MANUAL.md +++ b/doc/MANUAL.md @@ -118,6 +118,20 @@ If other devices are connected and powered from ULX3S J1/J2 GPIO/PMOD connectors then more than 0.5A may be required - board can draw 2-3A when externally loaded. +On J2 connector there are 2 pins for 5V external power input +and output. They are located on top right, near pin labeled 27 +and US2 connector. On PCB v2.0 and later boards, both J2 5V pins are +connected to US2 5V but there are onboard jumpers which can be +carefully cut and schottky diodes soldered on their pads to route the +5V power in and/or out of the board. + +Powering only from 3.3V is not possible because switching regulators +need 5V to generate 2.5V and 1.1V. + +Switching regulators use ferrite core coils L1,L2,L3 which can saturate +at magnetic fields above 0.3T. Never approach neodymium magnets +near powered board. + # Low Power Mode RTC without battery will keep waking up the board as factory default. @@ -167,17 +181,6 @@ but reconfigure USB chip to turn D18 OFF: ftx_prog --cbus 3 DRIVE_0 -On J2 connector there are 2 pins for 5V external power input -and output. They are located on top right, near pin labeled 27 -and US2 connector. Power is unidirectionaly routed using schottky -diodes. - -Powering only from 3.3V is not possible because switching regulators -need 5V to generate 2.5V and 1.1V. - -Switching regulators use ferrite core coils L1,L2,L3 which can saturate -at magnetic fields above 0.3T. Never approach neodymium magnets -near powered board. # Programming options