UMFT220XA-01 FTDI, UMFT220XA-01 Datasheet - Page 9

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UMFT220XA-01

Manufacturer Part Number
UMFT220XA-01
Description
Interface Development Tools USB to SPI/FT1248 Dev Mod for FT220X
Manufacturer
FTDI
Type
USB to SPIr
Datasheet

Specifications of UMFT220XA-01

Rohs
yes
Product
Development Modules
Tool Is For Evaluation Of
FT220XQ
Interface Type
SPI
Operating Supply Voltage
3.3 V
Dimensions
30.1 mm x 12.2 mm x 2.2 mm
Tradename
X-Chip
5.4
Figure 5.2 – Self-Powered Configuration
A self-powered configuration operates on the principle of drawing power from an external power supply,
as oppose to drawing power from the USB host. In this configuration no current is drawn from the USB
bus.
Figure 5.2 illustrates the UMFT220XA in a typical USB self-powered configuration. In this case the solder
links connection of JP1 is removed, which allows 5V power to be supplied to the module VCC pins from an
external source. VCCIO can to be powered from 3V3OUT or the VCC of an external source. (Note that
Figure 5.2 is for illustration only and that the pins do not actually go all the way through the PCB)
For a self-powered configuration it is necessary to prevent current from flowing back to the USB data
lines when the connected USB host or hub has powered down. To carry out this function the UMFT220XA
uses an on-board voltage divider network connected to the USB power bus and RESET# pin. This
operates on the principle that when no power is supplied to the VBUS line, the FT220X will automatically
be held in reset by a weak pull-down, when power is applied the voltage divider will apply a weak 3.3V
pull-up. Driving a level to the RESET# pin of the UMFT220XA will override the effect of this voltage
divider. When the FT220X is in reset the USB DP signal pull-up resistor connected to the data lines is
disconnected and no current can flow down the USB lines.
An example of interfacing the FT220X with a Microcontroller‟s FT1248 interface is also illustrated in Figure
5.2. This example shows the wire configuration of the transfer and handshake lines. This example also
illustrates that a voltage other than 3.3V can be supplied to the FT220X‟s IO port, this feature is
described further and for bus powered mode in Section 5.6.
Alternatively both the FT220X‟s IO port and MCU can be powered from the 3V3OUT pin; this approach is
described in Section 5.5.
Vcc = 1.8V – 3.3V
VIO
Self Powered Configuration
MCU
IO0
SCLK
MISO
SS#
Solder Link JP1 - Open
Variable TTL
GND
Mode
Copyright © 2012 Future Technology Devices International Limited
Optional
Optional
Optional
IO0
IO1
IO2
IO3
Viewing Pin thourgh the board
Document Reference No.: FT_000517
3V3OUT
VCCIO
from the top.
VBUS
VCC
Solder Link JP2 - Open
Self Power
Clearance No.: FTDI#
Mode
SCLK
MISO
SS#
9
UMFT220XA
Vcc = 5V
Version 1.1
267

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