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
DRIVE 1
DRIVE 0
CBUS5, CBUS6
CBUS5, CBUS6
CBUS5, CBUS6
IO Pad is tri-stated
Output a constant 1
Output a constant 0
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.
PWREN#
SLEEP#
CBUS5, CBUS6
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
CLK12MHz
CLK6MHz
CBUS5, CBUS6
CBUS5, CBUS6
CBUS5, CBUS6
24 MHz Clock output.*
12 MHz Clock output.*
6 MHz Clock output.*
Battery charge Detect, indicates when the device is
connected to a dedicated battery charger host. Active high
output.
BCD Charger
CBUS5, CBUS6
BCD
Charger#
CBUS5, CBUS6
CBUS5, CBUS6
Inverse of BCD Charger
Synchronous and asynchronous bit bang mode WR#
strobe output.
BitBang_WR#
Synchronous and asynchronous bit bang mode RD# strobe
output.
BitBang_RD#
VBUS Sense
Time Stamp
CBUS5, CBUS6
CBUS5, CBUS6
CBUS5, CBUS6
Input to detect when VBUS is present.
Toggle signal which changes state each time a USB SOF is
received
Prevents the device from entering suspend state when
unplugged.
Keep_Awake#
CBUS5, CBUS6
Table 3.9 CBUS Configuration Control
*When in USB suspend mode the outputs clocks are also suspended.
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