FT230X 参数 Datasheet PDF下载

FT230X USB TO BASIC UART IC

Document No.: FT_000566 Clearance No.: FTDI# 260

Version 1.2

6

USB Power Configurations

The following sections illustrate possible USB power configurations for the FT230X. The illustrations have

omitted pin numbers for ease of understanding since the pins differ between the FT230XS and FT230XQ

package options.

All USB power configurations illustrated apply to both package options for the FT230X device. Please refer

to Section 9 for the package option pin-out and signal descriptions.

6.1 USB Bus Powered Configuration

VCC

1

2

3

4

47pF

5

SHIELD

RESET#

10nF

VCCIO

GND

47pF

FT230X

Ferrite

Bead

VCC

27R

USBDM

27R

USBDP

3V3OUT

AG

ND

GN

D

GND

VCC

100nF

+

4.7uF

GND

100nF

GND

Figure 6.1 Bus Powered Configuration

device gets its power from the USB bus. Basic rules for USB bus power devices are as follows –

i) On plug-in to USB, the device should draw no more current than 100mA.

ii) In USB Suspend mode the device should draw no more than 2.5mA.

iii) 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.

iv) A device that consumes more than 100mA cannot be plugged into a USB bus powered hub.

v) No device can draw more than 500mA from the USB bus.

The power descriptors in the internal MTP memory of the FT230X 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 FT230X 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

Laird Technologies (http://www.lairdtech.com) for example Laird Technologies Part # MI0805K601R-10.

Copyright © 2013 Future Technology Devices International Limited

22