UMFT201XA-01 FTDI, UMFT201XA-01 Datasheet - Page 9

• Manufacturer Part Number: UMFT201XA-01
• Description: Interface Development Tools USB to I2C Dev Module for FT201X
• Manufacturer: FTDI
• Type: USB to I2Cr

Specifications of UMFT201XA-01

• Rohs: yes
• Product: Development Modules
• Tool Is For Evaluation Of: FT201XQ
• Interface Type: I2C, USB
• Operating Supply Voltage: 3.3 V
• Dimensions: 30.2 mm x 12.2 mm
• Tradename: X-Chip

UMFT201XA Datasheet
Version 1.1
266
Document Reference No.: FT_000516
Clearance No.: FTDI#
Self Powered Configuration
5.4
Vcc = 1.8V – 3.3V
Vcc = 5V
VIO
SCL
SCL
SDA
SDA
MCU
VCCIO
VCC
3V3OUT
VBUS
GND
Self Power
Variable TTL
Mode
Mode
Solder Link JP2 - Open
Solder Link JP1 - Open
Viewing pins thourgh the board
from the top.
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 UMFT201XA in a typical USB self-powered configuration. In this case the solder
link 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 UMFT201XA
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 FT201X 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 UMFT201XA will override the effect of this voltage
divider. When the FT201X 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.
2
An example of interfacing the FT201X with a Microcontroller‟s I
C interface is also illustrated in Figure
5.2.
9
Copyright © 2012 Future Technology Devices International Limited