Copyright © 2013 Future Technology Devices International Limited

11

FT240X USB 8-BIT FIFO IC Datasheet

Version 1.3

Document No.: FT_000626 Clearance No.:

FTDI# 259

3.5 CBUS Signal Options

The following options can be configured on the CBUS I/O pins. CBUS signal options are common to both

package versions of the FT240X. These options can be configured in the internal MTP memory using the

software utility FT_PPROG, which can be downloaded from the FTDI Utilities (www.ftdichip.com). The

default configuration is described in Section 8.

CBUS

Signal

Option

Available On CBUS Pin

Description

TRI-STATE

CBUS5, CBUS6

IO Pad is tri-stated

DRIVE 1

CBUS5, CBUS6

Output a constant 1

DRIVE 0

CBUS5, CBUS6

Output a constant 0

PWREN#

CBUS5, CBUS6

Output is low after the device has been configured by

USB, then high during USB suspend mode. This output can

be used to control power to external logic P-Channel logic

level MOSFET switch. Enable the interface pull-down

option when using the PWREN# in this way.

SLEEP#

CBUS5, CBUS6

Goes low during USB suspend mode. Typically used to

power down an external TTL to RS232 level converter IC

in USB to RS232 converter designs.

CLK24MHz

CBUS5, CBUS6

24 MHz Clock output.*

CLK12MHz

CBUS5, CBUS6

12 MHz Clock output.*

CLK6MHz

CBUS5, CBUS6

6 MHz Clock output.*

BCD Charger

CBUS5, CBUS6

Battery charge Detect, indicates when the device is

connected to a dedicated battery charger host. Active high

output.

BCD

Charger#

CBUS5, CBUS6

Inverse of BCD Charger

BitBang_WR#

CBUS5, CBUS6

Synchronous and asynchronous bit bang mode WR#

strobe output.

BitBang_RD#

CBUS5, CBUS6

Synchronous and asynchronous bit bang mode RD# strobe

output.

VBUS Sense

CBUS5, CBUS6

Input to detect when VBUS is present.

Time Stamp

CBUS5, CBUS6

Toggle signal which changes state each time a USB SOF is

received

Keep_Awake#

CBUS5, CBUS6

Prevents the device from entering suspend state when

unplugged.

Table 3.9 CBUS Configuration Control

*When in USB suspend mode the outputs clocks are also suspended.