Copyright © 2010 Future Technology Devices International Limited 13
Document No.: FT_000173
FT2232D DUAL USB TO SERIAL UART/FIFO IC Datasheet
Version 2.05
Clearance No.: FTDI# 127
4 Function Description
The FT2232D is a USB to serial UART interface device which incorporates the functionality of two
of FTDI‟s second generation FT232BM and FT245BM chips into a single device. A single downstream
USB port is converted to two IO channels which can each be individually configured as a FT232BM-
style UART interface, or a FT245BM-style FIFO interface, without the need to add a USB hub. In
addition a new high drive level option means that the device UART / FIFO IO pins will drive out at
around three times the normal power level, meaning that the bus can be shared by several devices.
4.0 Key Features
Two Individually Configurable IO Channels: Each of the FT2232D‟s Channels (A and B) can be
individually configured as a FT232BM-style UART interface, or as a FT245BM-style FIFO interface. In addition
these channels can be configured in a number of special IO modes.
Integrated Power-On-Reset (POR) circuit: The device incorporates an internal POR function. A
RESET# pin is available to allow external logic to reset the device where required, however for most
applications this pin can simply be hardwired to Vcc. A RSTOUT# pin is provided in order to allow the new
POR circuit to provide a stable reset to external MCU and other devices.
Integrated RCCLK circuit: Used to ensure that the oscillator and clock multiplier PLL frequency are stable
prior to USB enumeration.
Integrated level converter on UART / FIFO interface and control signals: Each channel of the
FT2232D has its own independent VCCIO pin that can be supplied by between 3V to 5V. This allows each
channel‟s output voltage drive level to be individually configured. Thus allowing, for example 3.3V logic to
be interfaced to the device without the need for external level converter I.C.‟s.
Improved power management control for high-power USB Bus Powered devices: The PWREN# pin
will become active when the device is enumerated by USB, and be deactivated when the device is in USB
suspend. This can be used to directly drive a transistor or P-Channel MOSFET in applications where power
switching of external circuitry is required. The BM pull down enable feature (configured in the external
EEPROM) is also retained. This will make the device gently pull down on the FIFO / UART IO lines when the
power is shut off (PWREN# is high). In this mode any residual voltage on external circuitry is bled to GND
when power is removed, thus ensuring that external circuitry controlled by PWREN# resets reliably when
power is restored.
Send Immediate / Wake Up Signal Pin on each channel: There is a Send Immediate / Wake Up
(SI/WU) signal pins on each of the chips channels. These combine two functions on one pin. If USB is in
suspend mode (and remote wakeup is enabled in the EEPROM), strobing this pin low will cause the device
to request a resume from suspend (WakeUp) on the USB Bus. Normally, this can be used to wake up the
Host PC. During normal operation, if this pin is strobed low any data in the device RX buffer will be sent out
over USB on the next Bulk-IN request from the drivers regardless of the packet size. This can be used to
optimise USB transfer speed for some applications.
Low suspend current: The suspend current of the FT2232D is typically under 100 μA (excluding the 1.5K
pull up resistor on USBDP) in USB suspend mode. This allows greater margin for peripherals to meet the
USB Suspend current limit of 500uA.
Programmable Receive Buffer Timeout: The TX buffer timeout is programmable over USB in 1ms
increments from 1ms to 255ms, thus allowing the device to be better optimised for protocols requiring
faster response times from short data packets.
Relaxed VCC Decoupling: The improved level of Vcc decoupling that was incorporated into BM devices
has also been implemented in the FT2232D device.
Baud Rate Pre-Scaler Divisors: The FT2232D (UART mode) baud rate pre-scaler supports division by
(n+0), (n+0.125), (n+0.25), (n+0.375), (n+0.5), (n+0.625), (n+0.75) and (n+0.875) where n is an
integer between 2 and 16,384 (2
14
).
Extended EEPROM Support: The FT2232D supports 93C46 (64 x 16 bit), 93C56 (128 x 16 bit), and
93C66 (256 x 16 bit) EEPROMs. The extra space is not used by the device. However it is available for use
by other external MCU / logic whilst the FT2232D is being held in reset. There is now an additional 64 words
of space available (128bytes total) in the user area when a 93C56 or 93C66 is used.
USB 2.0 (full speed option): An EEPROM based option allows the FT2232D to return a USB 2.0 device
descriptor as opposed to USB 1.1. Note: The device would be a USB 2.0 Full Speed device (12Mb/s) as
opposed to a USB 2.0 High Speed device (480Mb/s).