FT221XQ-R International Semiconductor Technologies, FT221XQ-R Datasheet - Page 26

• Manufacturer Part Number: FT221XQ-R
• Description: Specifications: Applications: * ; Interface: * ; Voltage - Supply: 3.3 V ~ 5 V ; Package / Case: 20-VFQFN Exposed Pad ; Packaging: Digi-Reel
• Manufacturer: International Semiconductor Technologies

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The following sections illustrate possible USB power configurations for the FT221X. The illustrations have
omitted pin numbers for ease of understanding since the pins differ between the FT221XS and FT221XQ
package options.
All USB power configurations illustrated apply to both package options for the FT221X device. Please refer
to Section 3 for the package option pin-out and signal descriptions.
7.1 USB Bus Powered Configuration
Figure 7.1 Bus Powered Configuration
Figure 7.1 Illustrates the FT221X in a typical USB bus powered design configuration. A USB bus powered
device gets its power from the USB bus. Basic rules for USB bus power devices are as follows –
The power descriptors in the internal MTP memory of the FT221X should be programmed to match the
current drawn by the device.
A ferrite bead is connected in series with the USB power supply to reduce EMI noise from the FT221X and
associated circuitry being radiated down the USB cable to the USB host. The value of the Ferrite Bead
depends on the total current drawn by the application. A suitable range of Ferrite Beads is available from
Steward (www.steward.com), for example Steward Part # MI0805K601R-10.
i)
ii)
iii)
iv)
v)
USB Power Configurations
SHIELD
On plug-in to USB, the device should draw no more current than 100mA.
In USB Suspend mode the device should draw no more than 2.5mA.
A bus powered high power USB device (one that draws more than 100mA) should use one of
the CBUS pins configured as PWREN# and use it to keep the current below 100mA on plug-in
and 2.5mA on USB suspend.
A device that consumes more than 100mA cannot be plugged into a USB bus powered hub.
No device can draw more than 500mA from the USB bus.
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Copyright © 2013 Future Technology Devices International Limited
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2
3
4
100nF
GND
10nF
47pF
Ferrite
Bead
GND
VCC
+
GND
47pF
4.7uF
VCC
Document No.: FT_000630 Clearance No.: FTDI# 263
GND
27R
27R
100nF
USBDM
USBDP
VCC
3V3OUT
RESET#
VCCIO
FT221X
Version 1.2
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