Copyright © 2013 Future Technology Devices International Limited 1
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
Future Technology
Devices International Ltd.
FT231X
(USB to FULL HANDSHAKE UART IC)
The FT231X is a USB to serial UART
interface with full modem control and
the following advanced features:
Single chip USB to asynchronous serial data
transfer interface.
Entire USB protocol handled on the chip. No
USB specific firmware programming required.
Fully integrated 2048 byte multi-time-
programmable (MTP) memory, storing device
descriptors and CBUS I/O configuration.
Fully integrated clock generation with no
external crystal required plus optional clock
output selection enabling glue-less interface
to external MCU or FPGA.
Data transfer rates from 300 baud to 3 Mbaud
(RS422, RS485, and RS232 ) at TTL levels.
512 byte receive buffer and 512 byte transmit
buffer utilising buffer smoothing technology to
allow for high data throughput.
FTDI’s royalty-free Virtual Com Port (VCP)
and Direct (D2XX) drivers eliminate the
requirement for USB driver development in
most cases.
Configurable CBUS I/O pins.
Transmit and receive LED drive signals.
UART interface support for 7 or 8 data bits, 1
or 2 stop bits and odd / even / mark / space
no parity
Synchronous and asynchronous bit bang
interface options with RD# and WR# strobes.
USB Battery Charger Detection. Allows for USB
peripheral devices to detect the presence of a
higher power source to enable improved
charging.
Device supplied pre-programmed with unique
USB serial number.
USB Power Configurations; supports bus-
powered, self-powered and bus-powered with
power switching
Integrated +3.3V level converter for USB I/O.
True 3.3V CMOS drive output and TTL input;
Operates down to 1V8 with external pull-ups.
Tolerant of 5V input.
Configurable I/O pin output drive strength; 4
mA(min) and 16 mA(max).
Integrated power-on-reset circuit.
Fully integrated AVCC supply filtering - no
external filtering required.
UART signal inversion option.
+ 5V Single Supply Operation.
Internal 3V3/1V8 LDO regulators
Low operating and USB suspend current; 8mA
(active-typ) and 125uA (suspend-typ).
UHCI/OHCI/EHCI host controller compatible
USB 2.0 Full Speed capable.
Extended operating temperature range; -40 to
85⁰C.
Available in compact, Pb-free, 20 Pin SSOP and
QFN packages (both RoHS compliant).
Neither the whole nor any part of the information contained in, or the product described in this manual, may be adapted or reproduced
in any material or electronic form without the prior written consent of the copyright holder. This product and its documentation are
supplied on an as-is basis and no warranty as to their suitability for any particular purpose is either made or implied. Future Technology
Devices International Ltd will not accept any claim for damages howsoever arising as a result of use or failure of this produ ct. Your
statutory rights are not affected. This product or any variant of it is not intended for use in any medical appliance, device or system in
which the failure of the product might reasonably be expected to result in personal injury. This document provides preliminary
information that may be subject to change without notice. No freedom to use patents or other intellectual property rights is implied by
the publication of this document. Future Technology Devices International Ltd, Unit 1, 2 Seaward Place, Centurion Business Park, Glasgow
G41 1HH United Kingdom. Scotland Registered Company Number: SC136640
Copyright © 2013 Future Technology Devices International Limited 2
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
1 Typical Applications
USB to RS232/RS422/RS485 Converters
Upgrading Legacy Peripherals to USB
Utilising USB to add system modularity
Incorporate USB interface to enable PC
transfers for development system
communication
Cellular and Cordless Phone USB data transfer
cables and interfaces
Interfacing MCU/PLD/FPGA based designs to
add USB connectivity
USB Audio and Low Bandwidth Video data
transfer
USB Smart Card Readers
USB Instrumentation
USB Industrial Control
USB MP3 Player Interface
USB FLASH Card Reader and Writers
Set Top Box PC - USB interface
USB Digital Camera Interface
USB Hardware Modems
USB Wireless Modems
USB Bar Code Readers
USB dongle implementations for Software/
Hardware Encryption and Wireless Modules
Detection of dedicated battery charger ports for
high current charging of batteries in portable
devices.
1.1 Driver Support
Royalty free VIRTUAL COM PORT
(VCP) DRIVERS for...
Windows 8 32,64-bit
Windows 7 32,64-bit
Windows XP and XP 64-bit
Windows Vista and Vista 64-bit
Windows XP Embedded
Windows CE 4.2, 5.0 and 6.0
Mac OS-X
Linux 3.2 and greater
Android
Royalty free D2XX Direct Drivers
(USB Drivers + DLL S/W Interface)
Windows 8 32,64-bit
Windows 7 32,64-bit
Windows XP and XP 64-bit
Windows Vista and Vista 64-bit
Windows XP Embedded
Windows CE 4.2, 5.0 and 6.0
MAC OS-X
Linux 2.6 and greater
Android
The drivers listed above are all available to download for free from FTDI website (www.ftdichip.com).
Various 3rd party drivers are also available for other operating systems - see FTDI website
(www.ftdichip.com) for details.
For driver installation, please refer to http://www.ftdichip.com/Documents/InstallGuides.htm
1.2 Part Numbers
Package
20 Pin QFN
20 Pin SSOP
Note: Packing codes for x is:
- R: Taped and Reel, (SSOP is 2,000pcs per reel, QFN is 5,000pcs per reel).
- U: Tube packing, 58pcs per tube (SSOP only)
- T: Tray packing, 490pcs per tray (QFN only)
For example: FT231XQ-R is 5,000pcs taped and reel packing
Copyright © 2013 Future Technology Devices International Limited 3
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
1.3 USB Compliant
The FT231X is fully compliant with the USB 2.0 specification and has been given the USB-IF Test-ID (TID)
40001464 (Rev D).
Copyright © 2013 Future Technology Devices International Limited 4
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
2 FT231X Block Diagram
3.3 Volt LDO
Regulator 1.8 Volt LDO
Regulator
USB
Transceiver
with
Integrated
1.5k pullups
and battery
charge
detection
USB DPLL
Internal
12MHz
Oscillator
X4 Clock
Multiplier
Serial Interface
Engine
(SIE)
USB
Protocol Engine UART FIFO
Controller
UART Controller
with
Programmable
Signal Inversion
Baud Rate
Generator
Reset
Generator
FIFO TX Buffer
(512 bytes)
FIFO RX Buffer
(512 bytes)
Internal MTP
Memory
48MHz
GND
RESET#
To USB Transceiver Cell
3V3OUT
48MHz
3V3OUT
VCC
USBDP
USBDM
1V8 Internal
Core Supply
TXD
RXD
RTS#
CTS#
DTR#
DSR#
DCD#
RI#
CBUS0
CBUS1
CBUS2
CBUS3
Figure 2.1 FT231X Block Diagram
For a description of each function please refer to Section 4.
Copyright © 2013 Future Technology Devices International Limited 5
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
Table of Contents
1 Typical Applications ...................................................................... 2
1.1 Driver Support .................................................................................... 2
1.2 Part Numbers...................................................................................... 2
1.3 USB Compliant .................................................................................... 3
2 FT231X Block Diagram ................................................................. 4
3 Device Pin Out and Signal Description .......................................... 7
3.1 20-LD QFN Package ........................................................................... 7
3.1.1 QFN Package PinOut Description .................................................................................... 7
3.2 20-LD SSOP Package.......................................................................... 9
3.2.1 SSOP Package PinOut Description .................................................................................. 9
3.3 CBUS Signal Options ......................................................................... 10
4 Function Description................................................................... 13
4.1 Key Features ..................................................................................... 13
4.2 Functional Block Descriptions ........................................................... 13
5 Devices Characteristics and Ratings ........................................... 16
5.1 Absolute Maximum Ratings............................................................... 16
5.2 ESD and Latch-up Specifications ....................................................... 16
5.3 DC Characteristics............................................................................. 17
5.4 MTP Memory Reliability Characteristics ............................................ 21
5.5 Internal Clock Characteristics ........................................................... 21
6 USB Power Configurations .......................................................... 22
6.1 USB Bus Powered Configuration ...................................................... 22
6.2 Self Powered Configuration .............................................................. 23
6.3 USB Bus Powered with Power Switching Configuration .................... 24
7 Application Examples ................................................................. 25
7.1 USB to RS232 Converter ................................................................... 25
7.2 USB to RS485 Coverter ..................................................................... 26
7.3 USB to RS422 Converter ................................................................... 27
7.4 USB Battery Charging Detection ....................................................... 28
7.5 LED Interface .................................................................................... 30
8 Internal MTP Memory Configuration ........................................... 32
8.1 Default Values .................................................................................. 32
8.2 Methods of Programming the MTP Memory ....................................... 34
8.2.1 Programming the MTP memory over USB ...................................................................... 34
8.3 Memory Map ..................................................................................... 34
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FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
9 Package Parameters ................................................................... 36
9.1 SSOP-20 Package Mechanical Dimensions ........................................ 36
9.2 SSOP-20 Package Markings .............................................................. 37
9.3 QFN-20 Package Mechanical Dimensions .......................................... 38
9.4 QFN-20 Package Markings ................................................................ 39
9.5 Solder Reflow Profile ........................................................................ 40
10 Contact Information ................................................................... 41
Appendix A – References ........................................................................... 42
Appendix B – List of Figures and Tables .................................................... 42
Appendix C – Revision History ................................................................... 44
Copyright © 2013 Future Technology Devices International Limited 7
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Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
3 Device Pin Out and Signal Description
3.1 20-LD QFN Package
VCCIO 20
RI# 2
DTR# 18
GND
3
DSR# 4
RTS# 19
CTS# 6
CBUS2 7
USBDP
8USBDM
9
3V3OUT
10
RESET#
11
VCC 12
CBUS1 14
CBUS0 15
GND
13
TXD 17
DCD# 5
RXD 1
CBUS3 16
GND
21
Figure 3.1 QFN Schematic Symbol
3.1.1 QFN Package PinOut Description
Note: # denotes an active low signal.
Pin No.
Name
Type
Description
12
**
VCC
POWER
Input
5 V or 3V3 supply to IC
20
VCCIO
POWER
Input
1V8 – 3V3 supply for the IO cells
10
**
3V3OUT
POWER
Output
3V3 output at 50mA. May be used to power VCCIO.
When VCC is 3V3; pin 10 is an input pin and should be
connected to pin 12.
3, 13
GND
POWER
Input
0V Ground input.
Table 3.1 Power and Ground
*Pin 21 on the symbol is the pad under the centre of the chip package and should be connected to GND
** If VCC is 3V3 then 3V3OUT must also be driven with 3V3 input
Copyright © 2013 Future Technology Devices International Limited 8
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
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Document No.: FT_000565 Clearance No.: FTDI# 261
Pin No.
Name
Type
Description
9
USBDM
INPUT
USB Data Signal Minus.
8
USBDP
INPUT
USB Data Signal Plus.
11
RESET#
INPUT
Reset input (active low).
Table 3.2 Common Function pins
Pin No.
Name
Type
Description
17
TXD
Output
Transmit Asynchronous Data Output.
1
RXD
Input
Receiving Asynchronous Data Input.
19
RTS#
Output
Request to Send Control Output / Handshake Signal.
6
CTS#
Input
Clear To Send Control Input / Handshake Signal.
18
DTR#
Output
Data Terminal Ready Control Output / Handshake Signal.
4
DSR#
Input
Data Set Ready Control Input / Handshake Signal.
5
DCD#
Input
Data Carrier Detect Control Input.
2
RI#
Input
Ring Indicator input for remote wake up.
15
CBUS0
I/O
Configurable CBUS I/O Pin. Function of this pin is configured in the
device MTP memory. The default configuration is TXDEN. See CBUS
Signal Options, Table 3.7.
14
CBUS1
I/O
Configurable CBUS I/O Pin. Function of this pin is configured in the
device MTP memory. The default configuration is RXLED#. See CBUS
Signal Options, Table 3.7.
7
CBUS2
I/O
Configurable CBUS I/O Pin. Function of this pin is configured in the
device MTP memory. The default configuration is TXLED#. See CBUS
Signal Options, Table 3.7.
16
CBUS3
I/O
Configurable CBUS I/O Pin. Function of this pin is configured in the
device MTP memory. The default configuration is SLEEP#. See CBUS
Signal Options, Table 3.7.
Table 3.3 UART Interface and CBUS Group (see note 1)
Notes:
1 When used in Input Mode, the input pins are pulled to VCCIO via internal 75kΩ
(approx) resistors. These pins can be programmed to gently pull low during USB
suspend (PWREN# = “1”) by setting an option in the MTP memory.
Copyright © 2013 Future Technology Devices International Limited 9
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
3.2 20-LD SSOP Package
RXD 4
RI# 5
GND
6
DSR# 7
DCD# 8
CTS# 9
CBUS2 10
USBDP
11 USBDM
12
3V3OUT
13
RESET#
14
VCC 15
GND
16
CBUS1 17
CBUS0 18
CBUS3 19
TXD 20
DTR# 1
RTS# 2
VCCIO 3
Figure 3.2 SSOP Schematic Symbol
3.2.1 SSOP Package PinOut Description
Note: # denotes an active low signal.
Pin No.
Name
Type
Description
15
**
VCC
POWER
Input
5 V or 3V3 supply to IC
3
VCCIO
POWER
Input
1V8 – 3V3 supply for the IO cells
13
**
3V3OUT
POWER
Output
3V3 output at 50mA. May be used to power VCCIO.
When VCC is 3V3, pin 13 is an input pin.
6, 16
GND
POWER
Input
0V Ground input.
Table 3.4 Power and Ground
** If VCC is 3V3 then 3V3OUT must also be driven with 3V3 input
Pin No.
Name
Type
Description
12
USBDM
INPUT
USB Data Signal Minus.
11
USBDP
INPUT
USB Data Signal Plus.
14
RESET#
INPUT
Reset input (active low).
Table 3.5 Common Function pins
Copyright © 2013 Future Technology Devices International Limited 10
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
Pin No.
Name
Type
Description
20
TXD
Output
Transmit Asynchronous Data Output.
4
RXD
Input
Receiving Asynchronous Data Input.
2
RTS#
Output
Request to Send Control Output / Handshake Signal.
9
CTS#
Input
Clear To Send Control Input / Handshake Signal.
1
DTR#
Output
Data Terminal Ready Control Output / Handshake Signal.
7
DSR#
Input
Data Set Ready Control Input / Handshake Signal.
8
DCD#
Input
Data Carrier Detect Control Input.
5
RI#
Input
Ring Indicator input for remote wake up.
18
CBUS0
I/O
Configurable CBUS I/O Pin. Function of this pin is configured in the
device MTP memory. The default configuration is TXDEN. See CBUS
Signal Options, Table 3.7.
17
CBUS1
I/O
Configurable CBUS I/O Pin. Function of this pin is configured in the
device MTP memory. The default configuration is RXLED#. See CBUS
Signal Options, Table 3.7.
10
CBUS2
I/O
Configurable CBUS I/O Pin. Function of this pin is configured in the
device MTP memory. The default configuration is TXLED#. See CBUS
Signal Options, Table 3.7.
19
CBUS3
I/O
Configurable CBUS I/O Pin. Function of this pin is configured in the
device MTP memory. The default configuration is SLEEP#. See CBUS
Signal Options, Table 3.7.
Table 3.6 UART Interface and CBUS Group (see note 1)
Notes:
1 When used in Input Mode, the input pins are pulled to VCCIO via internal 75kΩ
(approx) resistors. These pins can be programmed to gently pull low during USB
suspend (PWREN# = “1”) by setting an option in the MTP memory.
3.3 CBUS Signal Options
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Datasheet
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Document No.: FT_000565 Clearance No.: FTDI# 261
The following options can be configured on the CBUS I/O pins. CBUS signal options are common to both
package versions of the FT231X. 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
CBUS0, CBUS1, CBUS2, CBUS3
IO Pad is tri-stated
DRIVE 1
CBUS0, CBUS1, CBUS2, CBUS3
Output a constant 1
DRIVE 0
CBUS0, CBUS1, CBUS2, CBUS3
Output a constant 0
TXDEN
CBUS0, CBUS1, CBUS2, CBUS3
Enable transmit data for RS485
PWREN#
CBUS0, CBUS1, CBUS2, CBUS3
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.
TXLED#
CBUS0, CBUS1, CBUS2, CBUS3
Transmit data LED drive – pulses low when transmitting
data via USB. See Section 7.5 for more details.
RXLED#
CBUS0, CBUS1, CBUS2, CBUS3
Receive data LED drive – pulses low when receiving data
via USB. See Section 7.5 for more details.
TX&RXLED#
CBUS0, CBUS1, CBUS2, CBUS3
LED drive – pulses low when transmitting or receiving data
via USB. See Section 7.5 for more details.
SLEEP#
CBUS0, CBUS1, CBUS2, CBUS3
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
CBUS0, CBUS1, CBUS2, CBUS3
24 MHz Clock output.*
CLK12MHz
CBUS0, CBUS1, CBUS2, CBUS3
12 MHz Clock output.*
CLK6MHz
CBUS0, CBUS1, CBUS2, CBUS3
6 MHz Clock output.*
GPIO
CBUS0, CBUS1, CBUS2, CBUS3
CBUS bit bang mode option. Allows up to 4 of the CBUS
pins to be used as general purpose I/O. Configured
individually for CBUS0, CBUS1, CBUS2 and CBUS3 in the
internal MTP memory. A separate application note,
AN232R-01, available from FTDI website
(www.ftdichip.com) describes in more detail how to use
CBUS bit bang mode.
BCD Charger
CBUS0, CBUS1, CBUS2, CBUS3
Battery Charge Detect, indicates when the device is
connected to a dedicated battery charger. Active high
output.
BCD
Charger#
CBUS0, CBUS1, CBUS2, CBUS3
Inverse of BCD Charger
BitBang_WR#
CBUS0, CBUS1, CBUS2, CBUS3
Synchronous and asynchronous bit bang mode WR#
strobe output.
BitBang_RD#
CBUS0, CBUS1, CBUS2, CBUS3
Synchronous and asynchronous bit bang mode RD# strobe
output.
VBUS Sense
CBUS0, CBUS1, CBUS2, CBUS3
Input to detect when VBUS is present.
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Document No.: FT_000565 Clearance No.: FTDI# 261
CBUS
Signal
Option
Available On CBUS Pin
Description
Time Stamp
CBUS0, CBUS1, CBUS2, CBUS3
Toggle signal which changes state each time a USB SOF is
received
Keep_Awake#
CBUS0, CBUS1, CBUS2, CBUS3
Prevents the device from entering suspend state when
unplugged.
Table 3.7 CBUS Configuration Control
*When in USB suspend mode the outputs clocks are also suspended.
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4 Function Description
The FT231X is a USB to full handshake serial UART interface device which simplifies USB implementations
and reduces external component count by fully integrating an MTP memory, and an integrated clock
circuit which requires no external crystal. It has been designed to operate efficiently with USB host
controllers by using as little bandwidth as possible when compared to the total USB bandwidth available.
4.1 Key Features
Functional Integration. Fully integrated MTP memory, clock generation, AVCC filtering, Power-On-
Reset (POR) and LDO regulators.
Configurable CBUS I/O Pin Options. The fully integrated MTP memory allows configuration of the
Control Bus (CBUS) functionality and drive strength selection. There are 4 configurable CBUS I/O pins.
These configurable options are detailed in section 3.3
The CBUS lines can be configured with any one of these output options by setting bits in the internal MTP
memory. The device is shipped with the most commonly used pin definitions pre-programmed – see
Section 8 for details.
Asynchronous Bit Bang Mode with RD# and WR# Strobes. The FT231X supports FTDI’s previous
chip generation bit-bang mode. In bit-bang mode, the eight UART lines can be switched from the regular
interface mode to an 8-bit general purpose I/O port. Data packets can be sent to the device and they will
be sequentially sent to the interface at a rate controlled by an internal timer (equivalent to the baud rate
pre-scalar). In the FT231X device this mode has been enhanced by outputting the internal RD# and
WR# strobes signals which can be used to allow external logic to be clocked by accesses to the bit-bang
I/O bus. This option will be described more fully in a separate application note available from FTDI
website (www.ftdichip.com).
Synchronous Bit Bang Mode. The FT231X supports synchronous bit bang mode. This mode differs from
asynchronous bit bang mode in that the interface pins are only read when the device is written to. This
makes it easier for the controlling program to measure the response to an output stimulus as the data
returned is synchronous to the output data. An application note, AN232R-01, available from FTDI website
(www.ftdichip.com) describes this feature.
Source Power and Power Consumption. The FT231X is capable of operating at a voltage supply
between +3.3V and +5.25V with a nominal operational mode current of 8mA and a nominal USB suspend
mode current of 125µA. This allows greater margin for peripheral designs to meet the USB suspend mode
current limit of 2.5mA. An integrated level converter within the UART interface allows the FT231X to
interface to UART logic running at +1.8V to +3.3V (5V tolerant).
4.2 Functional Block Descriptions
The following paragraphs detail each function within the FT231X. Please refer to the block diagram shown
in Figure 2.1
Internal MTP Memory. The internal MTP memory in the FT231X is used to store USB Vendor ID (VID),
Product ID (PID), device serial number, product description string and various other USB configuration
descriptors. The internal MTP memory is also used to configure the CBUS pin functions. The FT231X is
supplied with the internal MTP memory pre-programmed as described in Section 8. A user area of the
internal MTP memory is available to system designers to allow storing additional data from the user
application over USB. The internal MTP memory descriptors can be programmed in circuit, over USB
without any additional voltage requirement. The descriptors can be programmed using the FTDI utility
software called FT_PROG, which can be downloaded from FTDI Utilities on the FTDI website
(www.ftdichip.com).
+3.3V LDO Regulator. The +3.3V LDO regulator generates the +3.3V reference voltage for driving the
USB transceiver cell output buffers. It requires an external decoupling capacitor to be attached to the
3V3OUT regulator output pin. It also provides +3.3V power to the 1.5kΩ internal pull up resistor on
USBDP. The main function of the LDO is to power the USB Transceiver and the Reset Generator Cells
rather than to power external logic. However, it can be used to supply external circuitry requiring a
+3.3V nominal supply with a maximum current of 50mA.
+1.8V LDO Regulator. The +1.8V LDO regulator generates the +1.8V reference voltage for internal use
driving the IC core functions of the serial interface engine and USB protocol engine.
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USB Transceiver. The USB Transceiver Cell provides the USB 1.1 / USB 2.0 full-speed physical interface
to the USB cable. The output drivers provide +3.3V level slew rate control signalling, whilst a differential
input receiver and two single ended input receivers provide USB data in, Single-Ended-0 (SE0) and USB
reset detection conditions respectfully. This function also incorporates a 1.5kΩ pull up resistor on USBDP.
The block also detects when connected to a USB power supply which will not enumerate the device but
still supply power and may be used for battery charging.
USB DPLL. The USB DPLL cell locks on to the incoming NRZI USB data and generates recovered clock
and data signals for the Serial Interface Engine (SIE) block.
Internal 12MHz Oscillator – The Internal 12MHz Oscillator cell generates a 12MHz reference clock.
This provides an input to the x4 Clock Multiplier function. The 12MHz Oscillator is also used as the
reference clock for the SIE, USB Protocol Engine and UART FIFO controller blocks.
Clock Multiplier / Divider. The Clock Multiplier / Divider takes the 12MHz input from the Internal
Oscillator function and generates the 48MHz, 24MHz, 12MHz and 6MHz reference clock signals. The 48Mz
clock reference is used by the USB DPLL and the Baud Rate Generator blocks.
Serial Interface Engine (SIE). The Serial Interface Engine (SIE) block performs the parallel to serial
and serial to parallel conversion of the USB data. In accordance with the USB 2.0 specification, it
performs bit stuffing/un-stuffing and CRC5/CRC16 generation. It also verifies the CRC on the USB data
stream.
USB Protocol Engine. The USB Protocol Engine manages the data stream from the device USB control
endpoint. It handles the low level USB protocol requests generated by the USB host controller and the
commands for controlling the functional parameters of the UART in accordance with the USB 2.0
specification chapter 9.
FIFO RX Buffer (512 bytes). Data sent from the USB host controller to the UART via the USB data OUT
endpoint is stored in the FIFO RX (receive) buffer. Data is removed from the buffer to the UART transmit
register under control of the UART FIFO controller. (Rx relative to the USB interface).
FIFO TX Buffer (512 bytes). Data from the UART receive register is stored in the TX buffer. The USB
host controller removes data from the FIFO TX Buffer by sending a USB request for data from the device
data IN endpoint. (Tx relative to the USB interface).
UART FIFO Controller. The UART FIFO controller handles the transfer of data between the FIFO RX and
TX buffers and the UART transmit and receive registers.
UART Controller with Programmable Signal Inversion and High Drive. Together with the UART
FIFO Controller the UART Controller handles the transfer of data between the FIFO RX and FIFO TX
buffers and the UART transmit and receive registers. It performs asynchronous 7 or 8 bit parallel to serial
and serial to parallel conversion of the data on the RS232 (or RS422 or RS485) interface.
Control signals supported by UART mode include RTS, CTS, DSR, DTR, DCD and RI. The UART Controller
also provides a transmitter enable control signal pin option (TXDEN) to assist with interfacing to RS485
transceivers. RTS/CTS, DSR/DTR and XON / XOFF handshaking options are also supported. Handshaking
is handled in hardware to ensure fast response times. The UART interface also supports the RS232
BREAK setting and detection conditions.
Additionally, the UART signals can each be individually inverted and have a configurable high drive
strength capability. Both these features are configurable in the MTP memory.
Baud Rate Generator – The Baud Rate Generator provides a 16x clock input to the UART Controller
from the 48MHz reference clock. It consists of a 14 bit pre-scalar and 3 register bits which provide fine
tuning of the baud rate (used to divide by a number plus a fraction or “sub-integer”). This determines the
baud rate of the UART, which is programmable from 183 baud to 3 Mbaud.
The FT231X supports all standard baud rates and non-standard baud rates from 183 Baud up to 3
Mbaud. 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 ( = 214 ) 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 on the FTDI
website (www.ftdichip.com) for more details.
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RESET Generator – The integrated Reset Generator Cell provides a reliable power-on reset to the device
internal circuitry at power up. The RESET# input pin allows an external device to reset the FT231X.
RESET# can be tied to 3V3OUT.
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5 Devices Characteristics and Ratings
5.1 Absolute Maximum Ratings
The absolute maximum ratings for the FT231X devices are as follows. These are in accordance with the
Absolute Maximum Rating System (IEC 60134). Exceeding these may cause permanent damage to the
device.
Parameter
Value
Unit
Conditions
Storage Temperature
-65°C to 150°C
Degrees C
Floor Life (Out of Bag) At Factory Ambient
(30°C / 60% Relative Humidity)
168 Hours
(IPC/JEDEC J-
STD-033A MSL
Level 3
Compliant)*
Hours
Ambient Operating Temperature (Power
Applied)
-40°C to 85°C
Degrees C
MTTF FT231XS
TBD
Hours
MTTF FT231XQ
TBD
Hours
VCC Supply Voltage
-0.3 to +5.5
V
VCCIO IO Voltage
-0.3 to +4.0
V
DC Input Voltage – USBDP and USBDM
-0.5 to +3.63
V
DC Input Voltage – High Impedance
Bi-directionals (powered from VCCIO)
-0.3 to +5.8
V
DC Output Current – Outputs
22
mA
ESD Charge Device Mode(CDM)
500
V
Class III
ESD Human Body Mode (HDM)
2000
V
Class 2
Table 5.1 Absolute Maximum Ratings
* If devices are stored out of the packaging beyond this time limit the devices should be baked before
use. The devices should be ramped up to a temperature of +125°C and baked for up to 17 hours.
5.2 ESD and Latch-up Specifications
Description
Specification
Human Body Mode (HBM)
> ± 2kV
Machine mode (MM)
> ± 200V
Charged Device Mode (CDM)
> ± 500V
Latch-up
> ± 200mA
Table 5.2 ESD and Latch-Up Specifications
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5.3 DC Characteristics
DC Characteristics (Ambient Temperature = -40°C to +85°C)
Parameter
Description
Minimum
Typical
Maximum
Units
Conditions
VCC
VCC Operating Supply
Voltage
2.97
5
5.5
V
Normal Operation
VCC2
VCCIO Operating
Supply Voltage
1.62
---
3.63
V
Icc1
Operating Supply
Current
8
8
8.4
mA
Normal Operation
Icc2
Operating Supply
Current
125
μA
USB Suspend
3V3
3.3v regulator output
2.97
3.3
3.63
V
VCC must be
greater than 3V3
otherwise 3V3OUT
is an input which
must be driven
with 3.3V
Table 5.3 Operating Voltage and Current
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Parameter
Description
Minimum
Typical
Maximum
Units
Conditions
Voh
Output Voltage High
2.97
VCCIO
VCCIO
V
Ioh = +/-2mA
I/O Drive strength*
= 4mA
2.97
VCCIO
VCCIO
V
I/O Drive strength*
= 8mA
2.97
VCCIO
VCCIO
V
I/O Drive strength*
= 12mA
2.97
VCCIO
VCCIO
V
I/O Drive strength*
= 16mA
Vol
Output Voltage Low
0
0.4
V
Iol = +/-2mA
I/O Drive strength*
= 4mA
0
0.4
V
I/O Drive strength*
= 8mA
0
0.4
V
I/O Drive strength*
= 12mA
0
0.4
V
I/O Drive strength*
= 16mA
Vil
Input low Switching
Threshold
0.8
V
LVTTL
Vih
Input High Switching
Threshold
2.0
V
LVTTL
Vt
Switching Threshold
1.49
V
LVTTL
Vt-
Schmitt trigger negative
going threshold voltage
1.15
V
Vt+
Schmitt trigger positive
going threshold voltage
1.64
V
Rpu
Input pull-up resistance
40
75
190
KΩ
Vin = 0
Rpd
Input pull-down
resistance
40
75
190
KΩ
Vin =VCCIO
Iin
Input Leakage Current
-10
+/-1
10
μA
Vin = 0
Ioz
Tri-state output leakage
current
-10
+/-1
10
μA
Vin = 5.5V or 0
Table 5.4 I/O Pin Characteristics VCCIO = +3.3V (except USB PHY pins)
* The I/O drive strength and slow slew-rate are configurable in the MTP memory.
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Parameter
Description
Minimum
Typical
Maximum
Units
Conditions
Voh
Output Voltage High
2.25
VCCIO
VCCIO
V
Ioh = +/-2mA
I/O Drive strength*
= 4mA
2.25
VCCIO
VCCIO
V
I/O Drive strength*
= 8mA
2.25
VCCIO
VCCIO
V
I/O Drive strength*
= 12mA
2.25
VCCIO
VCCIO
V
I/O Drive strength*
= 16mA
Vol
Output Voltage Low
0
0.4
V
Iol = +/-2mA
I/O Drive strength*
= 4mA
0
0.4
V
I/O Drive strength*
= 8mA
0
0.4
V
I/O Drive strength*
= 12mA
0
0.4
V
I/O Drive strength*
= 16mA
Vil
Input low Switching
Threshold
0.8
V
LVTTL
Vih
Input High Switching
Threshold
0.8
V
LVTTL
Vt
Switching Threshold
1.1
V
LVTTL
Vt-
Schmitt trigger negative
going threshold voltage
0.8
V
Vt+
Schmitt trigger positive
going threshold voltage
1.2
V
Rpu
Input pull-up resistance
40
75
190
KΩ
Vin = 0
Rpd
Input pull-down
resistance
40
75
190
KΩ
Vin =VCCIO
Iin
Input Leakage Current
-10
+/-1
10
μA
Vin = 0
Ioz
Tri-state output leakage
current
-10
+/-1
10
μA
Vin = 5.5V or 0
Table 5.5 I/O Pin Characteristics VCCIO = +2.5V (except USB PHY pins)
* The I/O drive strength and slow slew-rate are configurable in the MTP memory.
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Parameter
Description
Minimum
Typical
Maximum
Units
Conditions
Voh
Output Voltage High
1.62
VCCIO
VCCIO
V
Ioh = +/-2mA
I/O Drive strength*
= 4mA
1.62
VCCIO
VCCIO
V
I/O Drive strength*
= 8mA
1.62
VCCIO
VCCIO
V
I/O Drive strength*
= 12mA
1.62
VCCIO
VCCIO
V
I/O Drive strength*
= 16mA
Vol
Output Voltage Low
0
0.4
V
Iol = +/-2mA
I/O Drive strength*
= 4mA
0
0.4
V
I/O Drive strength*
= 8mA
0
0.4
V
I/O Drive strength*
= 12mA
0
0.4
V
I/O Drive strength*
= 16mA
Vil
Input low Switching
Threshold
0.77
V
LVTTL
Vih
Input High Switching
Threshold
1.6
V
LVTTL
Vt
Switching Threshold
0.77
V
LVTTL
Vt-
Schmitt trigger negative
going threshold voltage
0.557
V
Vt+
Schmitt trigger positive
going threshold voltage
0.893
V
Rpu
Input pull-up resistance
40
75
190
KΩ
Vin = 0
Rpd
Input pull-down
resistance
40
75
190
KΩ
Vin =VCCIO
Iin
Input Leakage Current
-10
+/-1
10
μA
Vin = 0
Ioz
Tri-state output leakage
current
-10
+/-1
10
μA
Vin = 5.5V or 0
Table 5.6 I/O Pin Characteristics VCCIO = +1.8V (except USB PHY pins)
* The I/O drive strength and slow slew-rate are configurable in the MTP memory.
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Parameter
Description
Minimum
Typical
Maximum
Units
Conditions
Voh
Output Voltage High
VCC-0.2
V
Vol
Output Voltage Low
0.2
V
Vil
Input low Switching
Threshold
-
0.8
V
Vih
Input High Switching
Threshold
2.0
-
V
Table 5.7 USB I/O Pin (USBDP, USBDM) Characteristics
5.4 MTP Memory Reliability Characteristics
The internal 2048 Byte MTP memory has the following reliability characteristics:
Parameter
Value
Unit
Data Retention
10
Years
Write Cycle
2,000
Cycles
Read Cycle
Unlimited
Cycles
Table 5.8 MTP Memory Characteristics
5.5 Internal Clock Characteristics
The internal Clock Oscillator has the following characteristics:
Parameter
Value
Unit
Minimum
Typical
Maximum
Frequency of Operation
(see Note 1)
11.98
12.00
12.02
MHz
Clock Period
83.19
83.33
83.47
ns
Duty Cycle
45
50
55
%
Table 5.9 Internal Clock Characteristics
Note 1: Equivalent to +/-1667ppm
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6 USB Power Configurations
The following sections illustrate possible USB power configurations for the FT231X. The illustrations have
omitted pin numbers for ease of understanding since the pins differ between the FT231XS and FT231XQ
package options.
All USB power configurations illustrated apply to both package options for the FT231X device. Please refer
to Section 9 for the package option pin-out and signal descriptions.
6.1 USB Bus Powered Configuration
FT231X
1
2
3
4
5
SHIELD
Ferrite
Bead
GND
GND
VCC
GND
VCC
3V3OUT
USBDM
USBDP
VCCIO
VCC
GND
GND
RESET#
100nF
100nF
10nF
4.7uF+
27R
27R
GND
47pF 47pF
Figure 6.1 Bus Powered Configuration
Figure 6.1 Illustrates the FT231X in a typical USB bus powered design configuration. A USB bus powered
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 FT231X 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 FT231X 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 # MI0805K400R-10.
Note: If using PWREN# (available using the CBUS) the pin should be pulled to VCCIO using a 10kΩ
resistor.
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6.2 Self Powered Configuration
FT231X
1
2
3
4
5
SHIELD
GND
GND
VCC
GND
VCC
3V3OUT
USBDM
USBDP
VCCIO
VCC(3.3-5.25V)
AGND
GND
VBUS_SENSE
100nF
100nF
100nF
4.7uF
+
GND
4k7
10k
47pF
GND
47pF
27R
27R
RESET#
Figure 6.2 Self Powered Configuration
Figure 6.2 illustrates the FT231X in a typical USB self powered configuration. A USB self powered device
gets its power from its own power supply, VCC, and does not draw current from the USB bus. The basic
rules for USB self powered devices are as follows –
i) A self powered device should not force current down the USB bus when the USB host or hub
controller is powered down.
ii) A self powered device can use as much current as it needs during normal operation and USB
suspend as it has its own power supply.
iii) A self powered device can be used with any USB host, a bus powered USB hub or a self
powered USB hub.
The power descriptor in the internal MTP memory of the FT231X should be programmed to a value of
zero (self powered).
In order to comply with the first requirement above, the USB bus power (pin 1) is used to control the
VBUS_Sense pin of the FT220X device. When the USB host or hub is powered up an internal 1.5kΩ
resistor on USBDP is pulled up to +3.3V, thus identifying the device as a full speed device to the USB
host or hub. When the USB host or hub is powered off, VBUS_Sense pin will be low and the FT220X is
held in a suspend state. In this state the internal 1.5kΩ resistor is not pulled up to any power supply
(hub or host is powered down), so no current flows down USBDP via the 1.5kΩ pull-up resistor. Failure to
do this may cause some USB host or hub controllers to power up erratically.
Figure 6.2 illustrates a self powered design which has a +3.3V to +5.25V supply.
Note:
1. When the FT231X is in reset, the UART interface I/O pins are tri-stated. Input pins have internal
200kΩ pull-up resistors to VCCIO, so they will gently pull high unless driven by some external
logic.
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6.3 USB Bus Powered with Power Switching Configuration
FT231X
1
2
3
4
5
SHIELD
Ferrite
Bead
GND
GND
VCC
GND
VCC
3V3OUT
USBDM
USBDP
VCCIO
AGND
GND
RESET#
100nF
100nF
10nF
4.7uF+
CBUS3
PWREN#
10k
1k
Switched 5V Power to
External Logic
0.1uF0.1uF
P Channel Power
MOSFET
27R
27R
GND
47pF47pF
Figure 6.3 Bus Powered with Power Switching Configuration
A requirement of USB bus powered applications, is when in USB suspend mode, the application draws a
total current of less than 2.5mA. This requirement includes external logic. Some external logic has the
ability to power itself down into a low current state by monitoring the PWREN# signal. For external logic
that cannot power itself down in this way, the FT231X provides a simple but effective method of turning
off power during the USB suspend mode.
Figure 6.3 shows an example of using a discrete P-Channel MOSFET to control the power to external
logic. A suitable device to do this is an International Rectifier (www.irf.com) IRLML6402, or equivalent. It
is recommended that a “soft start” circuit consisting of a 1kΩ series resistor and a 0.1μF capacitor is used
to limit the current surge when the MOSFET turns on. Without the soft start circuit it is possible that the
transient power surge, caused when the MOSFET switches on, will reset the FT231X or the USB host/hub
controller. The soft start circuit example shown in Figure 6.3 powers up with a slew rate of
approximaely12.5V/ms. Thus supply voltage to external logic transitions from GND to +5V in
approximately 400 microseconds.
As an alternative to the MOSFET, a dedicated power switch IC with inbuilt “soft-start” can be used. A
suitable power switch IC for such an application is the Micrel (www.micrel.com) MIC2025-2BM or
equivalent.
With power switching controlled designs the following should be noted:
i) The external logic to which the power is being switched should have its own reset circuitry to
automatically reset the logic when power is re-applied when moving out of suspend mode.
ii) Set the Pull-down on Suspend option in the internal FT231X MTP memory.
iii) One of the CBUS Pins should be configured as PWREN# in the internal FT231X MTP memory, and
used to switch the power supply to the external circuitry. This should be pulled high through a 10
kΩ resistor.
iv) For USB high-power bus powered applications (one that consumes greater than 100mA, and up
to 500mA of current from the USB bus), the power consumption of the application must be set in
the Max Power field in the internal FT231X MTP memory. A high-power bus powered application
uses the descriptor in the internal FT231X MTP memory to inform the system of its power
requirements.
v) PWREN# gets its VCC from VCCIO. For designs using 3V3 logic, ensure VCCIO is not powered
down using the external logic. In this case use the +3V3OUT.
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7 Application Examples
The following sections illustrate possible applications of the FT231X. The illustrations have omitted pin
numbers for ease of understanding since the pins differ between the FT231XS and FT231XQ package
options.
7.1 USB to RS232 Converter
FT231X
1
2
3
4
5
SHIELD
Ferrite
Bead
GND
GND
VCC
GND
VCC
3V3OUT
USBDM
USBDP
VCCIO
VCC
AGND
GND
RESET#
100nF
100nF
10nF
4.7uF+
SLEEP#
CBUS1
CBUS2
TXD
RXD
RTS#
CTS#
DTR#
DSR#
DCD#
RI#
RS232 LEVEL
CONVERTER
TXDATA
RXDATA
RTS
CTS
DTR
DSR
DCD
RI
TXLED
RXLED
VCC VCC
270R 270R
GND
RI
DTR
CTS
TXDATA
RTS
RXDATA
DSR
DCD
DB9M
SHIELD 10
5
9
4
8
3
7
2
6
1
SHDN#CBUS0
TXD
RXD
RTS#
CTS#
DTR#
RI#
DCD#
DSR#
27R
27R
GND
47pF
47pF
NOTE: If design uses VCCIO < 3V3 then 10k pullup to VCCIO is required on IO lines
Figure 7.1 Application Example showing USB to RS232 Converter
An example of using the FT231X as a USB to RS232 converter is illustrated in Figure 7.1. In this
application, a 3V3 TTL to RS232 Level Converter IC is used on the serial UART interface of the FT231X to
convert the 3V3 levels of the FT231X to RS232 levels. This level shift can be done using line drivers from
a variety of vendors e.g. Zywyn. A useful feature on some of these devices is the SHDN# pin which can
be used to power down the device to a low quiescent current during USB suspend mode.
A suitable level shifting device is the Zywyn ZT3243F which is capable of RS232 communication at up to
1000k baud.
In example shown, the CBUS0 and CBUS1 have been configured as TXLED# and RXLED# and are being
used to drive two LEDs.
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7.2 USB to RS485 Coverter
FT231X
1
2
3
4
5
SHIELD
Ferrite
Bead
GND
GND
VCC
GND
VCC
3V3OUT
USBDM
USBDP
VCCIO
VCC
AGND
GND
RESET#
100nF
100nF
10nF
4.7uF+
TXD
RXD
GND DB9M
SHIELD 10
PWREN#
VCCIO
10K
RS485 LEVEL
CONVERTER
Vcc
ZT3485E
5
1
2
3
4
Link
120R
7
6
TXDEN
27R
27R
47pF 47pF
GND
Figure 7.2 Application Example Showing USB to RS485 Converter
An example of using the FT231X as a USB to RS485 converter is shown in Figure 7.2. In this application,
a 3V3-TTL to RS485 level converter IC is used on the serial UART interface of the FT231X to convert the
TTL levels of the FT231X to RS485 levels.
This example uses the Zywyn ZT3485 device. Equivalent devices are available from Maxim and Analogue
Devices. The ZT3485 is a RS485 device in a compact 8 pin SOP package. It has separate enables on both
the transmitter and receiver. With RS485, the transmitter is only enabled when a character is being
transmitted from the UART. The TXDEN signal CBUS pin option on the FT231X is provided for exactly this
purpose and so the transmitter enable is wired to CBUS2 which has been configured as TXDEN. Similarly,
CBUS3 has been configured as PWREN#. This signal is used to control the ZT3485’s receiver enable. The
receiver enable is active low, so it is wired to the PWREN# pin to disable the receiver when in USB
suspend mode. CBUS2 = TXDEN and CBUS3 = PWREN# are the default device configurations of the
FT231X pins.
RS485 is a multi-drop network; so many devices can communicate with each other over a two wire cable
interface. The RS485 cable requires to be terminated at each end of the cable. A link (which provides the
120Ω termination) allows the cable to be terminated if the ZT3485 is physically positioned at either end
of the cable.
In this example the data transmitted by the FT231X is also present on the receive path of the
ZT3485.This is a common feature of RS485 and requires the application software to remove the
transmitted data from the received data stream. With the FT231X it is possible to do this entirely in
hardware by modifying the example shown in Figure 7.2 by logically OR’ing the FT231X TXDEN and the
ZT3485 receiver output and connecting the output of the OR gate to the RXD of the FT231X.
Note that the TXDEN is activated 1 bit period before the start bit. TXDEN is deactivated at the same time
as the stop bit. This is not configurable.
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7.3 USB to RS422 Converter
FT231X
1
2
3
4
5
SHIELD
Ferrite
Bead
GND
GND
VCC
GND
VCC
3V3OUT
USBDM
USBDP
VCCIO
VCC
AGND
GND
RESET#
100nF
100nF
10nF
4.7uF+
RS422 LEVEL
CONVERTER
Vcc
ZT3491
5
3
4
76
TXDM
TXDP
RXDP
RXDM
120R
10
9
11
12
RS422 LEVEL
CONVERTER
ZT3491
3
4
76
Vcc
Vcc
10K
2
5
120R
11
12
9
10 RTSM
RTSP
CTSP
CTSM
GND DB9M
SHIELD
TXDM
TXDP
RXDP
RXDM
RTSM
RTSP
CTSP
CTSM
2
RXD
TXD
RTS#
CTS#
PWREN#
SLEEP#
GND
47pF 47pF
27R
27R
Figure 7.3 USB to RS422 Converter Configuration
An example of using the FT231X as a USB to RS422 converter is shown in Figure 7.3. In this application,
two 3V3-TTL to RS422 Level Converter Ics are used on the serial UART interface of the FT231X to convert
the TTL levels of the FT231X to RS422 levels. There are many suitable level converter devices available.
This example uses Zywyn ZT3491 devices which have enables on both the transmitter and receiver.
Since the ZT3491 transmitter enable is active high, it is connected to a CBUS pin in SLEEP#
configuration. The ZT3491 receiver enable is active low and is therefore connected to a CBUS pin
PWREN# configuration. This ensures that when both the ZT3491 transmitters and receivers are enabled
then the device is active, and when the device is in USB suspend mode, the ZT3491 transmitters and
receivers are disabled. If a similar application is used, but the design is USB BUS powered, it may be
necessary to use a P-Channel logic level MOSFET (controlled by PWREN#) in the VCC line of the ZT3491
devices to ensure that the USB standby current of 2.5mA is met.
The ZT3491 is specified to transmit and receive data at a rate of up to 16 Mbaud. In this example the
maximum data rate is limited to 3 Mbaud by the FT231X.
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7.4 USB Battery Charging Detection
A recent addition to the USB specification (http://www.usb.org/developers/devclass_docs/BCv1.2_011912.zip) is
to allow for additional charging profiles to be used for charging batteries in portable devices. These
charging profiles do not enumerate the USB port of the peripheral. The FT231X device will detect that a
USB compliant dedicated charging port (DCP) is connected. Once detected while in suspend mode, a
battery charge detection signal is provided to allow external logic to switch to charging mode as opposed
to operation mode.
To use the FT231X with battery charging detection the CBUS pins must be reprogrammed to allow for the
BCD Charger output to switch the external charger circuitry on. The CBUS pins are configured in the
internal MTP memory with the free utility FTPROG. If the charging circuitry requires an active low signal
to enable it, the CBUS pin can be programmed to BCD Charger# as an alternative.
When connected to a USB compliant dedicated charging port (DCP, as opposed to a standard USB host)
the device USB signals will be shorted together and the device suspended. The BCD charger signal will
bring the LTC4053 out of suspend and allow battery charging to start. The charge current in the example
below is 1A as defined by the resistance on the PROG pin.
X-Chip Pin Function
EEPROM Setting
CBUS0 BCD Battery Options
Battery Charger Enable
Force Power Enable
De-acticate Sleep
X
GND
GND
0.1uF 0.1uF
GND
GND
600R/2A
10nF
VBUS 3V3OUT
0.1uF
0R
GNDSLD GND
27R
27R
VBUS 1
D- 2
D+ 3
GND 5
ID 4
CN USB
VCC
2
FAULT
3
TIMER
4
GND
5NTC 6
PROG 7
SHDN 8
BAT 9
ACPR 10
CHRG
1
GND 11
LTC4053EDD
GND
3V3OUT 3V3OUT
4.7uF
0.1uF
GND
VBUSVBUS
GND
VBATT
GND
GND
1K5
GND
1
TB3.5mm
VBUS VBUS
NTC
0.1uF
GND
VBUS
1uF
1R
GND
VBUS
BCD
2K2
GND
JP1
1-2
2-3 NCT Enabled
NCT Available
JP1
SIP-3
NTC
GND
NCT Disabled (Default)
JUMPER-2mm
4K32 1%
GND
DP
DM
3V3OUT
RESET#
VCC
GND
CBUS0
VCCIO
FT231X
BCD
1A when connected to a dedicated charger port
0A when enumerated
0A when in sleep
0A when not enumerated and not in sleep
+
-
NCT
N.F.
Figure 7.4 USB Battery Charging Detection (1 pin)
Alternatively the PWREN# And SLEEP pins may be used to control the LTC4053 such that a battery may
be charged from a standard host (low current) or from a dedicated charging port (high current). In such
a design as shown below the charge current would need to be limited to 0.4A to ensure that the USB host
power limit is not exceeded.
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X-Chip Pin Function
EEPROM Setting
CBUS5
CBUS6 SLEEP#
PWREN#
Battery Options
Battery Charger Enable
Force Power Enable
De-acticate Sleep X
X
X
SLEEP#
PWREN#
DP
DM
3V3OUT
VCORE
RESET#
VCC
CBUS6
CBUS5
VCCIO
U1
FT231X
0.4A when connected to a dedicated charger port
GND
GND
0.1uF 0.1uF
GND
GND
600R/2A
10nF
VBUS 3V3OUT
0.1uF
0R
GNDSLD GND
27R
27R
VBUS 1
D- 2
D+ 3
GND 5
ID 4
CN USB
3V3OUT 3V3OUTVBUS VBUS
N.F.
16K5 1%
GND
4K32 1%
PWREN#
0.4A when enumerated
0A when in sleep mode
0.1A when not enumerated and not in sleep mode
VCC
2
FAULT
3
TIMER
4
GND
5NTC 6
PROG 7
SHDN 8
BAT 9
ACPR 10
CHRG
1
GND 11
LTC4053EDD
GND
4.7uF
0.1uF
GND
VBUSVBUS
GND
VBATT
GND
GND 1
TB3.5mm
NTC
0.1uF
GND
VBUS
1uF
1R
GND
VBUS
2K2
GND
JP1
1-2
2-3 NCT Enabled
NCT Available
JP1
SIP-3
NTC
GND
NCT Disabled (Default)
JUMPER-2mm
4K32 1%
+
-
NCT
SLEEP#
Figure 7.5 USB Battery Charging Detection (2 pin)
In the example above the FT231X SLEEP pin is used to enable/disable the LTC4053, while the PWREN#
signal alters the charging current by altering the resistance on the LTC4053 PROG pin.
A third option shown in the example below uses the SLEEP signal from the FT231X to enable / disable the
battery charger. The BCD# and PWREN# signals are then used to alter the resistance on the PROG pin of
the LTC4053 which controls the charge current drawn from the USB connector.
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X-Chip Pin Function
EEPROM Setting
CBUS0
CBUS1
CBUS2
BCD#
PWREN#
SLEEP#
Battery Options
Battery Charger Enable
Force Power Enable
De-acticate Sleep X
X
PWREN#
GND
CBUS2 10
DP
DM
3V3OUT
RESET#
VCC
GND
CBUS1 17
CBUS0 18
VCCIO
FT231X
BCD#
SLEEP#
GND
GND
0.1uF 0.1uF
GND
GND
600R/2A
10nF
VBUS 3V3OUT
0.1uF
0R
GNDSLD GND
27R
27R
VBUS 1
D- 2
D+ 3
GND 5
ID 4
CN USB
3V3OUT 3V3OUTVBUS VBUS
N.F.
1K5 - 1%16K5 1%
GND
BCD#
4K32 1%
PWREN#
1A when connected to a dedicated charger port
0.4A when enumerated
0A when in sleep
0.1A when not enumerated and not in sleep
VCC
2
FAULT
3
TIMER
4
GND
5NTC 6
PROG 7
SHDN 8
BAT 9
ACPR 10
CHRG
1
GND 11
LTC4053EDD
GND
4.7uF
0.1uF
GND
VBUSVBUS
GND
VBATT
GND
GND 1
TB3.5mm
NTC
0.1uF
GND
VBUS
1uF
1R
GND
VBUS
2K2
GND
JP1
1-2
2-3 NCT Enabled
NCT Available
JP1
SIP-3
NTC
GND
NCT Disabled (Default)
JUMPER-2mm
4K32 1%
+
-
NCT
SLEEP#
Figure 7.6 USB Battery Charging Detection (3 pin)
To calculate the equivalent resistance on the LTC4053 PROG pin select a charge current, then Res =
1500V/Ichg
For more configuration options of the LTC4053 refer to:
AN_175_Battery Charging Over USB
Note: If the FT231X is connected to a standard host port such that the device is enumerated the battery
charge detection signal is inactive as the device will not be in suspend.
7.5 LED Interface
Any of the CBUS I/O pins can be configured to drive an LED. The FT231X has 3 configuration options for
driving LEDs from the CBUS. These are TXLED#, RXLED#, and TX&RXLED#. Refer to Section 3.3 for
configuration options.
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FT231X
CBUS[0...3]
CBUS[0...3]
VCCIO
TX
TXLED#
RXLED#
RX
270R 270R
Figure 7.7 Dual LED Configuration
An example of using the FT231X to drive LEDs is shown in Figure 7.7. In this application one of the CBUS
pins is used to indicate transmission of data (TXLED#) and another is used to indicate receiving data
(RXLED#). When data is being transmitted or received the respective pins will drive from tri-state to low
in order to provide indication on the LEDs of data transfer. A digital one-shot is used so that even a small
percentage of data transfer is visible to the end user.
FT231X
CBUS[0...3] TX&RXLED#
270R
VCCIO
LED
Figure 7.8 Single LED Configuration
Another example of using the FT231X to drive LEDs is shown in Figure 7.8. In this example one of the
CBUS pins is used to indicate when data is being transmitted or received by the device (TX&RXLED). In
this configuration the FT231X will drive only a single LED.
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8 Internal MTP Memory Configuration
The FT231X includes an internal MTP memory which holds the USB configuration descriptors, other
configuration data for the chip and also user data areas. Following a power-on reset or a USB reset the
FT231X will scan its internal MTP memory and read the USB configuration descriptors stored there.
In many cases, the default values programmed into the MTP memory will be suitable and no re-
programming will be necessary. The defaults can be found in Section 8.1.
The MTP memory in the FT231X can be programmed over USB if the values need to be changed for a
particular application. Further details of this are provided from section 0 onwards.
Users who do not have their own USB Vendor ID but who would like to use a unique Product ID in their
design can apply to FTDI for a free block of unique PIDs. See TN_100 – USB Vendor ID/Product ID
Guidelines for more details.
8.1 Default Values
The default factory programmed values of the internal MTP memory are shown in Table 8.1.
Parameter
Value
Notes
USB Vendor ID (VID)
0403h
FTDI default VID (hex)
USB Product UD (PID)
6015h
FTDI default PID (hex)
Serial Number Enabled?
Yes
Serial Number
See Note
A unique serial number is generated and
programmed into the MTP memory during device
final test.
Pull down I/O Pins in USB
Suspend
Disabled
Enabling this option will make the device pull down
on the UART interface lines when in USB suspend
mode (PWREN# is high).
Manufacturer Name
FTDI
Product Description
FT231X USB UART
Max Bus Power Current
90mA
Power Source
Bus Powered
Device Type
FT231X
USB Version
0200
Returns USB 2.0 device description to the host.
Note: The device is a USB 2.0 Full Speed device
(12Mb/s) as opposed to a USB 2.0 High Speed
device (480Mb/s).
Remote Wake Up
Enabled
Taking RI# low will wake up the USB host controller
from suspend in approximately 20 ms.
DBUS Drive Current
Strength
4mA
Options are 4mA, 8mA, 12mA, 16mA
DBUS slew rate
Slow
Options are slow or fast
DBUS Schmitt Trigger
Enable
Normal
Options are normal or Schmitt
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Parameter
Value
Notes
CBUS Drive Current
Strength
4mA
Options are 4mA, 8mA, 12mA, 16mA
CBUS slew rate
Slow
Options are slow or fast
CBUS Schmitt Trigger
Enable
Normal
Options are normal or Schmitt
Load VCP Driver
Enabled**
Makes the device load the VCP driver interface for
the device.
CBUS0
TXDEN
Default configuration of CBUS0 – Transmit data
enable for RS485
CBUS1
RXLED#
Default configuration of CBUS1 – Receive LED drive.
CBUS2
TXLED#
Default configuration of CBUS2 – Transmit LED
drive.
CBUS3
SLEEP#
Default configuration of CBUS3 – SLEEP#. Logic 0
when the device is in suspend.
Invert TXD
Disabled
Signal on this pin becomes TXD# if enable.
Invert RXD
Disabled
Signal on this pin becomes RXD# if enable.
Invert RTS#
Disabled
Signal on this pin becomes RTS if enable.
Invert CTS#
Disabled
Signal on this pin becomes CTS if enable.
Invert DTR#
Disabled
Signal on this pin becomes DTR if enable.
Invert DSR#
Disabled
Signal on this pin becomes DSR if enable.
Invert DCD#
Disabled
Signal on this pin becomes DCD if enable.
Invert RI#
Disabled
Signal on this pin becomes RI if enable.
Table 8.1 Default Internal MTP Memory Configuration
**VCP disabled in Rev B silicon in error.
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8.2 Methods of Programming the MTP Memory
8.2.1 Programming the MTP memory over USB
The MTP memory on all FT-X devices can be programmed over USB. This method is the same as for the
EEPROM on other FTDI devices such as the FT232R. No additional hardware, connections or programming
voltages are required. The device is simply connected to the host computer in the same way that it would
be for normal applications, and the FT_Prog utility is used to set the required options and program the
device.
The FT_Prog utility is provided free-of-charge from the FTDI website, and can be found at the link below.
The user guide is also available at this link.
http://www.ftdichip.com/Support/Utilities.htm#FT_Prog
Additionally, D2XX commands can be used to program the MTP memory from within user applications.
For more information on the commands available, please see the D2XX Programmers Guide below.
http://www.ftdichip.com/Support/Documents/ProgramGuides/D2XX_Programmer’s_Guide(FT_000071).p
df
8.3 Memory Map
The FT-X family MTP memory has various areas which come under three main categories:
User Memory Area
Configuration Memory Area (writable)
Configuration Memory Area (non-writable)
Memory Area Description
Word Address
User Memory Area 2
Accessible via USB
0x3FF – 0x80
Configuration Memory Area
Accessible via USB
0x7E – 0x50
Configuration Memory Area
Cannot be written
0x4E – 0x40
User Memory Area 1
Accessible via USB
0x3E – 0x12
Configuration Memory Area
Accessible via USB
0x10 – 0x00
Figure 8.1: Simplified memory map for the FT-X
User Memory Area
The User Memory Areas are highlighted in Green on the memory map. They can be read and written via
USB on the FT231X. All locations within this range are freely programmable; no areas have special
functions and there is no checksum for the user area.
Note that the application should take into account the specification for the number of write cycles in
Section 5.4 if it will be writing to the MTP memory multiple times.
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Configuration Memory Area (writable)
This area stores the configuration data for the device, including the data which is returned to the host in
the configuration descriptors (e.g. the VID, PID and string descriptions) and also values which set the
hardware configuration (the signal assigned to each CBUS pin for example).
These values can have a significant effect on the behaviour of the device. Steps must be taken to ensure
that these locations are not written to un-intentionally by an application which is intended to access only
the user area.
This area is included in a checksum which covers configuration areas of the memory, and so changing
any value can also cause this checksum to fail.
Configuration Memory Area (non-writable)
This is a reserved area and the application should not write to this area of memory. Any attempt to write
these locations will fail.
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9 Package Parameters
The FT231X is available in two different packages. The FT231XS is the SSOP-20 option and the FT231XQ
is the QFN-20 package option. The solder reflow profile for both packages is described in Section 0.
9.1 SSOP-20 Package Mechanical Dimensions
Figure 9.1 SSOP-20 Package Dimensions
The FT231XS is supplied in a RoHS compliant 20 pin SSOP package. The package is lead (Pb) free and
uses a ‘green’ compound. The package is fully compliant with European Union directive 2002/95/EC.
This package is nominally 8.66mm x 3.91mm body (8.66mm x 5.99mm including pins). The pins are on a
0.635 mm pitch. The above mechanical drawing shows the SSOP-20 package.
.
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9.2 SSOP-20 Package Markings
Figure 9.2 SSOP-20 Package Markings
The date code format is YYXX where XX = 2 digit week number, YY = 2 digit year number. This is
followed by the revision number.
The code XXXXXXXXXXXX is the manufacturing LOT code.
FT231XS
1 10
1120
-B
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9.3 QFN-20 Package Mechanical Dimensions
Figure 9.3 QFN-20 Package Dimensions
The FT231XQ is supplied in a RoHS compliant leadless QFN-20 package. The package is lead ( Pb ) free,
and uses a ‘green’ compound. The package is fully compliant with European Union directive 2002/95/EC.
This package is nominally 4.00mm x 4.00mm. The solder pads are on a 0.50mm pitch. The above
mechanical drawing shows the QFN-20 package. All dimensions are in millimetres.
The centre pad on the base of the FT231XQ is internally connected to ground.
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9.4 QFN-20 Package Markings
Figure 9.4 QFN-20 Package Markings
The date code format is YYXX where XX = 2 digit week number, YY = 2 digit year number. This is
followed by the revision number.
The code XXXXXXX is the manufacturing LOT code.
FTDI
I
XXXXXXXXXX
FT231XQ
6
1
YYWW-B
10
15
20
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9.5 Solder Reflow Profile
The FT231X is supplied in Pb free 20 LD SSOP and QFN-20 packages. The recommended solder reflow
profile for both package options is shown in Figure 9.5.
Figure 9.5 FT231X Solder Reflow Profile
The recommended values for the solder reflow profile are detailed in Table 9.1. Values are shown for both
a completely Pb free solder process (i.e. the FT231X is used with Pb free solder), and for a non-Pb free
solder process (i.e. the FT231X is used with non-Pb free solder).
Profile Feature
Pb Free Solder Process
Non-Pb Free Solder Process
Average Ramp Up Rate (Ts to Tp)
3°C / second Max.
3°C / Second Max.
Preheat
- Temperature Min (Ts Min.)
- Temperature Max (Ts Max.)
- Time (ts Min to ts Max)
150°C
200°C
60 to 120 seconds
100°C
150°C
60 to 120 seconds
Time Maintained Above Critical Temperature
TL:
- Temperature (TL)
- Time (tL)
217°C
60 to 150 seconds
183°C
60 to 150 seconds
Peak Temperature (Tp)
260°C
240°C
Time within 5°C of actual Peak Temperature
(tp)
20 to 40 seconds
20 to 40 seconds
Ramp Down Rate
6°C / second Max.
6°C / second Max.
Time for T= 25°C to Peak Temperature, Tp
8 minutes Max.
6 minutes Max.
Table 9.1 Reflow Profile Parameter Values
Critical Zone: when
T is in the range
T to T
Temperature, T (Degrees C)
Time, t (seconds)
25 P
T = 25º C to T
tp
Tp
TL
t
Preheat
S
tL
Ramp Up Lp
Ramp
Down
T Max
S
T Min
S
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10 Contact Information
Head Office – Glasgow, UK
Future Technology Devices International Limited
Unit 1, 2 Seaward Place, Centurion Business Park
Glasgow G41 1HH
United Kingdom
Tel: +44 (0) 141 429 2777
Fax: +44 (0) 141 429 2758
E-mail (Sales)
sales1@ftdichip.com
E-mail (Support)
support1@ftdichip.com
E-mail (General Enquiries)
admin1@ftdichip.com
Branch Office – Taipei, Taiwan
Future Technology Devices International Limited
(Taiwan)
2F, No. 516, Sec. 1, NeiHu Road
Taipei 114
Taiwan , R.O.C.
Tel: +886 (0) 2 8791 3570
Fax: +886 (0) 2 8791 3576
E-mail (Sales)
tw.sales1@ftdichip.com
E-mail (Support)
tw.support1@ftdichip.com
E-mail (General Enquiries)
tw.admin1@ftdichip.com
Branch Office – Tigard, Oregon, USA
Future Technology Devices International Limited
(USA)
7130 SW Fir Loop
Tigard, OR 97223-8160
USA
Tel: +1 (503) 547 0988
Fax: +1 (503) 547 0987
E-Mail (Sales)
us.sales@ftdichip.com
E-Mail (Support)
us.support@ftdichip.com
E-Mail (General Enquiries)
us.admin@ftdichip.com
Branch Office – Shanghai, China
Future Technology Devices International Limited
(China)
Room 408, 317 Xianxia Road,
Shanghai, 200051
China
Tel: +86 21 62351596
Fax: +86 21 62351595
E-mail (Sales)
cn.sales@ftdichip.com
E-mail (Support)
cn.support@ftdichip.com
E-mail (General Enquiries)
cn.admin@ftdichip.com
Web Site
http://ftdichip.com
System and equipment manufacturers and designers are responsible to ensure that their systems, and any Future Technology
Devices International Ltd (FTDI) devices incorporated in their systems, meet all applicable safety, regulatory and system-level
performance requirements. All application-related information in this document (including application descriptions, suggested
FTDI devices and other materials) is provided for reference only. While FTDI has taken care to assure it is accurate, this
information is subject to customer confirmation, and FTDI disclaims all liability for system designs and for any applications
assistance provided by FTDI. Use of FTDI devices in life support and/or safety applications is entirely at the user’s risk, and the
user agrees to defend, indemnify and hold harmless FTDI from any and all damages, claims, suits or expense resulting from
such use. This document is subject to change without notice. No freedom to use patents or other intellectual property rights is
implied by the publication of this document. Neither the whole nor any part of the information contained in, or the product
described in this document, may be adapted or reproduced in any material or electronic form without the prior written consent
of the copyright holder. Future Technology Devices International Ltd, Unit 1, 2 Seaward Place, Centurion Business Park,
Glasgow G41 1HH, United Kingdom. Scotland Registered Company Number: SC136640
.
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Appendix A – References
Useful Application Notes
http://www.ftdichip.com/Documents/AppNotes/AN232R-01_FT231XBitBangModes.pdf
http://www.ftdichip.com/Documents/AppNotes/AN_107_AdvancedDriverOptions_AN_000073.pdf
http://www.ftdichip.com/Documents/AppNotes/AN_121_FTDI_Device_EEPROM_User_Area_Usage.pdf
http://www.ftdichip.com/Documents/AppNotes/AN_120_Aliasing_VCP_Baud_Rates.pdf
http://www.ftdichip.com/Documents/AppNotes/AN_100_Using_The_FT232_245R_With_External_Osc(FT_
000067).pdf
http://www.ftdichip.com/Resources/Utilities/AN_126_User_Guide_For_FT232_Factory%20test%20utility.
pdf
http://www.ftdichip.com/Documents/AppNotes/AN232B-05_BaudRates.pdf
http://www.ftdichip.com/Documents/InstallGuides.htm
http://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_100_USB_VID-PID_Guidelines.pdf
http://www.ftdichip.com/Support/Documents/AppNotes/AN_175_Battery%20Charging%20Over%20USB
%20with%20FTEX%20Devices.pdf
http://cds.linear.com/docs/Datasheet/4053-4.2fs.pdf
http://cds.linear.com/docs/Design%20Note/dn320f.pdf
http://www.usb.org/developers/devclass_docs/BCv1.2_011912.zip
Appendix B – List of Figures and Tables
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Document No.: FT_000565 Clearance No.: FTDI# 261
List of Figures
Figure 2.1 FT231X Block Diagram ................................................................................................... 4
Figure 3.1 QFN Schematic Symbol .................................................................................................. 7
Figure 3.2 SSOP Schematic Symbol ................................................................................................ 9
Figure 6.1 Bus Powered Configuration ........................................................................................... 22
Figure 6.2 Self Powered Configuration ........................................................................................... 23
Figure 6.3 Bus Powered with Power Switching Configuration ............................................................ 24
Figure 7.1 Application Example showing USB to RS232 Converter ..................................................... 25
Figure 7.2 Application Example Showing USB to RS485 Converter .................................................... 26
Figure 7.3 USB to RS422 Converter Configuration ........................................................................... 27
Figure 7.4 USB Battery Charging Detection (1 pin).......................................................................... 28
Figure 7.5 USB Battery Charging Detection (2 pin).......................................................................... 29
Figure 7.6 USB Battery Charging Detection (3 pin).......................................................................... 30
Figure 7.7 Dual LED Configuration ................................................................................................ 31
Figure 7.8 Single LED Configuration .............................................................................................. 31
Figure 8.1: Simplified memory map for the FT-X ............................................................................ 34
Figure 9.1 SSOP-20 Package Dimensions ....................................................................................... 36
Figure 9.2 SSOP-20 Package Markings .......................................................................................... 37
Figure 9.3 QFN-20 Package Dimensions ......................................................................................... 38
Figure 9.4 QFN-20 Package Markings ............................................................................................ 39
Figure 9.5 FT231X Solder Reflow Profile......................................................................................... 40
List of Tables
Table 3.1 Power and Ground .......................................................................................................... 7
Table 3.2 Common Function pins .................................................................................................... 8
Table 3.3 UART Interface and CBUS Group (see note 1) .................................................................... 8
Table 3.4 Power and Ground .......................................................................................................... 9
Table 3.5 Common Function pins .................................................................................................... 9
Table 3.6 UART Interface and CBUS Group (see note 1) .................................................................. 10
Table 3.7 CBUS Configuration Control ........................................................................................... 12
Table 5.1 Absolute Maximum Ratings ............................................................................................ 16
Table 5.2 ESD and Latch-Up Specifications .................................................................................... 16
Table 5.3 Operating Voltage and Current ....................................................................................... 17
Table 5.4 I/O Pin Characteristics VCCIO = +3.3V (except USB PHY pins) ........................................... 18
Table 5.5 I/O Pin Characteristics VCCIO = +2.5V (except USB PHY pins) ........................................... 19
Table 5.6 I/O Pin Characteristics VCCIO = +1.8V (except USB PHY pins) ........................................... 20
Table 5.7 USB I/O Pin (USBDP, USBDM) Characteristics .................................................................. 21
Table 5.8 MTP Memory Characteristics ........................................................................................... 21
Table 5.9 Internal Clock Characteristics ......................................................................................... 21
Table 8.1 Default Internal MTP Memory Configuration ..................................................................... 33
Table 9.1 Reflow Profile Parameter Values ..................................................................................... 40
Copyright © 2013 Future Technology Devices International Limited 44
FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
Appendix C – Revision History
Document Title: USB to FULL HANDSHAKE UART IC FT231X
Document Reference No.: FT_000565
Clearance No.: FTDI# 261
Product Page: http://www.ftdichip.com/FT-X.htm
Document Feedback: Send Feedback
Version Draft Initial draft available 2nd December 2011
Version 1.0 Initial release 8th February 2012
Version 1.1 Added USB compliance in section 1.3 17th April 2012
Clarified MTP Reliability in table 5.8
Section 8.1, Added a Note “VCP disabled in
Rev B Silicon in error
Version 1.2 updated front page to clarify 5V tolerant 15 February 2013
Updated TID