FT245RQ-REEL FTDI, FT245RQ-REEL Datasheet - Page 22

• Manufacturer Part Number: FT245RQ-REEL
• Description: USB Interface IC USB to Parallel FIFO Enhanced IC QFN-32
• Manufacturer: FTDI

Specifications of FT245RQ-REEL

• Mounting Style: SMD/SMT
• Package / Case: QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7
The following sections illustrate possible USB power configurations for the FT245R. The illustrations have
omitted pin numbers for ease of understanding since the pins differ between the FT245RL and FT245RQ
package options.
All USB power configurations illustrated apply to both package options for the FT245R 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 FT245R 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 EEPROM of the FT245R 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 FT245R 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 # MI0805K400R-10.
Note: If using PWREN#, the pin should be pulled to VCCIO using a 10kΩ resistor.
i)
ii)
iii)
iv)
v)
USB Power Configurations
SHIELD
5
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 the
PWREN# 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.
100nF
1
2
3
4
Copyright © 2010 Future Technology Devices International Limited
10nF
4.7uF
GND
GND
VCC
+
Ferrite
Bead
Vcc
FT245R USB FIFO IC Datasheet Version 2.10
100nF
GND
OSCI
USBDM
OSCO
USBDP
VCCIO
RESET#
NC
3V3OUT
VCC
NC
G
A
N
D
G
N
D
FT245R
G
N
D
Document No.: FT_000052
GND
G
N
D
Clearance No.: FTDI# 39
E
S
T
T
PWREN#
TXE#
RXF#
RD#
WR
D0
D1
D2
D4
D5
D6
D7
D3
Vcc
10K
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