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参数资料
| 型号： | FT245RQ-REEL |
| 厂商： | FTDI, Future Technology Devices International Ltd |
| 文件页数： | 18/37页 |
| 文件大小： | 0K |
| 描述： | IC USB TO PARALLEL FIFO 32-QFN |
| 产品培训模块： | USB Introduction |
| 标准包装： | 1 |
| 应用： | USB 至 FIFO 控制器 |
| 接口： | USB，FIFO，（同步/异步） |
| 电源电压： | 1.8 V ~ 5.25 V |
| 封装/外壳： | 32-VFQFN 裸露焊盘 |
| 供应商设备封装： | 32-QFN 裸露焊盘（5x5） |
| 包装： | 标准包装 |
| 安装类型： | 表面贴装 |
| 产品目录页面： | 634 (CN2011-ZH PDF) |
| 配用： | 768-1020-ND - MOD USB PARALLEL FIFO DEV FT245R |
| 其它名称： | 768-1012-6 |
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Copyright 2010 Future Technology Devices International Limited
25
Document No.: FT_000052
FT245R USB FIFO IC Datasheet Version 2.12
Clearance No.: FTDI# 39
v) PWREN# gets its VCC from VCCIO. For designs using 3V3 logic, ensure VCCIO is not powered
down using the external logic. In this case use the +3V3OUT.
7.4 USB Bus Powered with Selectable External Logic Supply
FT245R
A
G
N
D
G
N
D
G
N
D
G
N
D
T
E
S
T
100nF
3V3OUT
VCCIO
NC
RESET#
NC
10nF
D0
D1
D2
D3
D4
D5
D6
D7
TXE#
WR#
RD#
RXF#
USBDP
USBDM
VCC
1
2
3
4
5
OSCI
OSCO
PWREN#
Ferrite
Bead
+
SHIELD
GND
3.3V or 5V Supply
to External Logic
100nF
+
100nF
Vcc
4.7uF
GND
1
Jumper
2
3
Vcc
VCCIO
10k
VCCIO
Figure 7.4 USB Bus Powered with +3.3V or +5V External Logic Power Supply
Figure 7.4 illustrates a USB bus power application with selectable external logic supply. The external logic
can be selected between +3.3V and +5V using the jumper switch. This jumper is used to allow the
FT245R to be interfaced with a +3.3V or +5V logic devices. The VCCIO pin is either supplied with +5V
from the USB bus (jumper pins1 and 2 connected), or from the +3.3V output from the FT245R 3V3OUT
pin (jumper pins 2 and 3 connected). The supply to VCCIO is also used to supply external logic.
With bus powered applications, the following should be noted:
i)
To comply with the 2.5mA current supply limit during USB suspend mode, PWREN# or
SLEEP# signals should be used to power down external logic in this mode. If this is not
possible, use the configuration shown in Section 9.
ii)
The maximum current sourced from the USB bus during normal operation should not exceed
100mA, otherwise a bus powered design with power switching (Section 7.3) should be used.
Another possible configuration could use a discrete low dropout (LDO) regulator which is supplied by the
5V on the USB bus to supply between +1.8V and +2.8V to the VCCIO pin and to the external logic. In
this case VCC would be supplied with the +5V from the USB bus and the VCCIO would be supplied from
the output of the LDO regulator. This results in the FT245R I/O pins driving out at between +1.8V and
+2.8V logic levels.
For a USB bus powered application, it is important to consider the following when selecting the regulator:
i)
The regulator must be capable of sustaining its output voltage with an input voltage of
+4.35V. An Low Drop Out (LDO) regulator should be selected.
ii)
The quiescent current of the regulator must be low enough to meet the total current
requirement of <= 2.5mA during USB suspend mode.
A suitable series of LDO regulators that meets these requirements is the MicroChip/Telcom
(www.microchip.com) TC55 series of devices. These devices can supply up to 250mA current and have a
quiescent current of under 1μA.
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相关代理商/技术参数 |
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|---|---|
| FT245RQ-TRAY | 制造商:Future Technology Devices International (FTDI Chip) 功能描述:Single Chip USB Tray |
| FT24B3 031175 | 制造商:Comair Rotron 功能描述:FAN 120X120X25MM 24VDC |
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| FT24B3-E2 | 制造商:Comair Rotron 功能描述:FAN FLIGHT II 120X120X25 24V |
| FT24C02A | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Two-Wire Serial EEPROM |
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