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参数资料
| 型号： | FT245RQ-REEL |
| 厂商： | FTDI, Future Technology Devices International Ltd |
| 文件页数： | 16/37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
23
Document No.: FT_000052
FT245R USB FIFO IC Datasheet Version 2.12
Clearance No.: FTDI# 39
7.2 Self Powered Configuration
Figure 7.2 Self Powered Configuration
Figure 7.2 illustrates the FT245R in a typical USB self powered configuration. A USB self powered device
gets its power from its own power supply, VCC, and does not draw current from the USB bus. The basic
rules for USB self powered devices are as follows –
i)
A self powered device should not force current down the USB bus when the USB host or hub
controller is powered down.
ii)
A self powered device can use as much current as it needs during normal operation and USB
suspend as it has its own power supply.
iii)
A self powered device can be used with any USB host, a bus powered USB hub or a self
powered USB hub.
The power descriptor in the internal EEPROM of the FT245R should be programmed to a value of zero
(self powered).
In order to comply with the first requirement above, the USB bus power (pin 1) is used to control the
RESET# pin of the FT245R device. When the USB host or hub is powered up an internal 1.5kΩ resistor
on USBDP is pulled up to +3.3V (generated using the 4K7 and 10k resistor network), thus identifying the
device as a full speed device to the USB host or hub. When the USB host or hub is powered off, RESET#
will be low and the FT245R is held in reset. Since RESET# is low, the internal 1.5kΩ resistor is not pulled
up to any power supply (hub or host is powered down), so no current flows down USBDP via the 1.5kΩ
pull-up resistor. Failure to do this may cause some USB host or hub controllers to power up erratically.
Error! Reference source not found. illustrates a self powered design which has a +4V to +5.25V
upply.
Note:
1. When the FT232R is in reset, the UART interface I/O pins are tri-stated. Input pins have internal
200kΩ pull-up resistors to VCCIO, so they will gently pull high unless driven by some external
logic.
2. When using internal FT232R oscillator the VCC supply voltage range must be +4.0V to 5.25V.
3. When using external oscillator the VCC supply voltage range must be +3.3V to 5.25V
Any design which interfaces to +3.3 V or +1.8V would be having a +3.3V or +1.8V supply to
VCCIO.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| FT24B3-E2 | 制造商:Comair Rotron 功能描述:FAN FLIGHT II 120X120X25MM 24V |
| 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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