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Lower Supply Voltage -
Previous generations of the chip required 5V supply on the VCC pin. The FT232R will work
with a Vcc supply in the range 3.3V - 5.25V. Bus powered designs would still take their supply from the 5V on the USB
bus, but for self powered designs where only 3.3V is available and there is no 5V supply there is no longer any need
for an additional external regulator.
Integrated Level Converter on UART Interface and Control Signals
- VCCIO pin supply can be from 1.8V to 5V.
Connecting the VCCIO pin to 1.8V, 2.8V, or 3.3V allows the device to directly interface to 1.8V, 2.8V or 3.3V and other
logic families without the need for external level converter I.C. devices.
5V / 3.3V / 2.8V / 1.8V Logic Interface -
The FT232R provides
true
CMOS Drive Outputs and TTL level Inputs.
Integrated Power-On-Reset (POR) Circuit-
The device incorporates an internal POR function. A RESET# pin is
available in order to allow external logic to reset the FT232R where required. However, for many applications the
RESET# pin can be left unconnected, or pulled up to VCCIO.
Lower Operating and Suspend Current -
The device operating supply current has been further reduced to 15mA,
and the suspend current has been reduced to around 70μA. This allows greater margin for peripheral designs to meet
the USB suspend current limit of 500μA.
Low USB Bandwidth Consumption -
The operation of the USB interface to the FT232R has been designed to use
as little as possible of the total USB bandwidth available from the USB host controller.
High Output Drive Option -
The UART interface and CBUS I/O pins can be made to drive out at three times the
standard signal drive level thus allowing multiple devices to be driven, or devices that require a greater signal drive
strength to be interfaced to the FT232R. This option is enabled in the internal EEPROM.
Power Management Control for USB Bus Powered, High Current Designs-
The PWREN# signal can be used to
directly drive a transistor or P-Channel MOSFET in applications where power switching of external circuitry is required.
An option in the internal EEPROM makes the device gently pull down on its UART interface 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.
UART Pin Signal Inversion -
The sense of each of the eight UART signals can be individually inverted by setting
options in the internal EEPROM. Thus, CTS# (active low) can be changed to CTS (active high), or TXD can be
changed to TXD#.
FTDIChip-ID™ -
Each FT232R is assigned a unique number which is burnt into the device at manufacture. This ID
number cannot be reprogrammed by product manufacturers or end-users. This allows the possibility of using FT232R
based dongles for software licensing. Further to this, a renewable license scheme can be implemented based on the
FTDIChip-ID™ number when encrypted with other information. This encrypted number can be stored in the user area
of the FT232R internal EEPROM, and can be decrypted, then compared with the protected FTDIChip-ID™ to verify
that a license is valid. Web based applications can be used to maintain product licensing this way. An application note
describing this feature is available separately from the
FTDI website.
Improved EMI Performance -
The reduced operating current and improved on-chip VCC decoupling significantly
improves the ease of PCB design requirements in order to meet FCC, CE and other EMI related specifications.
Programmable Receive Buffer Timeout -
The receive buffer timeout is used to flush remaining data from the
receive buffer. This time defaults to 16ms, but is programmable over USB in 1ms increments from 1ms to 255ms, thus
allowing the device to be optimised for protocols that require fast response times from short data packets.
Baud Rates -
The FT232R supports all standard baud rates and non-standard baud rates from 300 Baud up to 3
Megabaud. Achievable non-standard baud rates are calculated as follows -
Baud Rate = 3000000 / (n +
x)
where n can be any integer between 2 and 16,384 ( = 2
14
) and
x
can be a sub-integer of the value 0, 0.125, 0.25,
0.375, 0.5, 0.625, 0.75, or 0.875. When n = 1,
x
= 0, i.e. baud rate divisors with values between 1 and 2 are not
possible.
This gives achievable baud rates in the range 183.1 baud to 3,000,000 baud. When a non-standard baud rate is
required simply pass the required baud rate value to the driver as normal, and the FTDI driver will calculate the
required divisor, and set the baud rate. See FTDI application note AN232B-05 for more details.
MM232R Mini USB-Serial UART Development Module Datasheet Version 1.00
© Future Technology Devices International Ltd. 2005
FTDI [ FUTURE TECHNOLOGY DEVICES INTERNATIONAL LTD. ]
