Datasheet

4D SYSTEMS PICadillo-35T Display Module
© 2014 4D SYSTEMS Page 18 of 31 www.4dsystems.com.au
4. Powering the PICadillo-35T
USB Power 4.1.
The PICadillo-35T is able to be powered numerous
ways, however the most common will be using the
USB Mini jack, which is also used to program the
display module.
The PICadillo-35T runs off a 5.0V DC supply, and
draws approximately 250mA using an average
arrangement of features at any given time. This is
within the suitable limits of supply for most
computers USB ports, however in some cases a
powered USB hub or external power supply may
be required.
There is a 500mA PTC resettable fuse located on
the 5V line coming from the USB, to protect the
computer against excessive current draw which
may damage your PC if any unfortunate events
occur while developing with the PICadillo-35T.
DC Barrel Jack 4.2.
The PICadillo-35T Features a DC Barrel Jack,
designed for a fine pitch DC Jack, 2.35mm in
diameter, with a centre hole of 0.7mm, and barrel
length of 8mm or more.
A suitable 1 Amp 5.0V DC Adaptor is available from
the 4D Systems website, which has been designed
specifically for 4D Systems.
The Barrel Jack on board is a CUI Inc PJ1-023-SMT
if more information is required.
Powering from the Headers 4.3.
The PICadillo-35T is able to be powered off the
Arduino style headers. There is a VIN pin located
on Pin 8 of the P2 Header. This pin accepts only
5.0VDC, with a maximum input of approximately
5.5VDC. Input outside this range could damage the
module as some peripherals run directly of the 5V
bus.
There is also a +5V pin, located on Pin 5 of the P2
header. This is NOT designed for direct input, this
is an output pin for supplying external devices.
This pin comes after the reverse polarity
protection, so it is designed for output only. This
pin will supply approximately VIN – 0.3V.
The Power Supplies 4.4.
On board the PICadillo-35T are two 3.3V
regulators. There are no 5.0V regulators, so power
input to the PICadillo-35T is required to be a
regulated 5.0V supply.
There is a dedicated LP2992IM5-3.3 3.3V 250mA
regulator for the PIC32 itself, which aims to
provide the PIC32 with an isolated supply so any
noise induced by external circuits will be at a
minimum relative to the PIC32’s supply.
There is then a 3.3V Max 1A regulator for the
peripherals and for the User, which is a
LP38692MP-3.3. This powers peripherals such as
the microSD card, and the display logic. The +3.3V
pin on the P2 header, is powered off this supply.
This supply is enabled by default, but there is a
single pad on the PCB labelled PER_DIS, which can
be grounded and this regulator will be disabled.
This may be useful for low power solutions.
The Audio Amplifier is powered directly off the 5V
bus, however its power supply is enabled/disabled
using the RB14 GPIO, which needs to be selected
using the J1 header.
The FTDI FT232RQ is powered off the 5V bus,
however features a simple switching circuit which
holds it in reset unless the USB cable is attached. If
powering the PICadillo-35T off the Barrel Jack or
5V header, then the FT232RQ will remain disabled.
The LCD Backlight is also powered directly off the
5V bus, and therefore the backlight may be
damaged if the display module is supplied with
power outside the recommended ranges.
When powering the display, multiple power
sources can be connected if desired, such as USB
and Barrel Jack, or USB and 5V Header Input.
There is a simple diode pair on board, so which
ever has the highest voltage will take over supply
to the display module. This protects multiple
supplies from fighting each other, and allows the
DC Barrel Jack to be used to power the display
while programming it over the USB port.