FT245BM Designers Guide

FT245BM Designers Guide
FT245BM Designers Guide
Version 2.0
Introduction
Welcome to the FT245BM Designer’s Guide. The Designers Guide includes printouts of a number of FT245BM
reference schematics and explanations of the key points of each schematic. These are intended to be used in
conjunction with the FT245BM data sheet, the current version of which should also be downloaded from the
FTDI web site.
The schematic files are downloadable separately as a ZIP archive which contains the schematics both in
OrCAD SDT 16-bit DOS format and in OrCAD Capture for Windows 32-bit format.
The OrCAD SDT 16-bit DOS format schematics are readable by OrCAD SDT version 3.2 and above. These
consist of files with the following extensions –
• .sch = OrCAD 16-bit DOS binary schematic file
• .lib = OrCAD 16-bit DOS binary component library file
• .src = OrCAD DOS library source ( text ) file
The OrCAD Capture for Windows schematics are readable by OrCAD Capture version 7.2 and above. These
consist of a file with a .dsn extension.
Notes for Protel users
OrCAD 16-bit DOS schematics can be imported into Protel schematic capture for Windows. Before reading in
the schematic ( .sch ) file, create a Protel library first by reading in the OrCAD library source ( .src ) file and
save it in Protel binary library format. Both OrCAD and Protel use the same default extensions for schematic
and library files, so if you do not wish to overwrite the original OrCAD files, save the Protel versions to a
different folder.
DG245 Version 2.0
© Future Technology Devices Intl. Ltd. 2002 / 2003
Page 1 of 14
CN1
CN-USB
5
C3
10uF
VCC
C2
0.1uF
DECOUPLING CAPS
1
2
3
4
FB1
2
27R
27R
R5
VCC
R4
C1
0.1uF
Y1
6MHz RESONATOR
RSTOUT#
C5
10nF
FERRITE BEAD
1
R6
VCC
C4
33nF
R2
2k2
1k5
VCC
31
2
1
32
4
28
27
5
7
8
6
C6
0.1uF
R3
470R
TEST
© Future Technology Devices Intl. Ltd. 2002 / 2003
CS
SK
DIN
DOUT
U1
VCC
10k
R1
SI/WU
RXF#
TXE#
WR
RD#
D7
D6
D5
D4
D3
D2
D1
D0
8
7
6
5
PWREN#
VCC
NC
NC
GND
93C46/56/66
( Optional )
1
2
3
4
EEDATA
EESK
EECS
RESET#
XTOUT
XTIN
RSTOUT#
USBDP
USBDM
3V3OUT
30
AVCC
AGND
29
3
26
13
VCC
VCC
VCC-IO
DG245 Version 2.0
GND
GND
IO16
IO17
IO20
IO21
IO22
IO23
D6
D7
RD#
WR
TXE#
RXF#
19
18
16
15
14
12
R7
47k
IO15
D5
20
RSTOUT#
IO14
D4
21
VCC
FT245BM
10
VCC-5v
FT245BM 5v BUS POWERED EXAMPLE
GND
5v MCU or Logic cct
RESET#
IO24
IO13
D3
22
PWREN#
IO12
D2
23
VCC
IO11
D1
24
11
IO10
D0
25
U2
VCC
C7
0.1uF
Figure 1.0
9
17
USB
FT245BM Designers Guide
FT245BM – 5 volt Bus Powered Example Schematic ( 245-5VB )
Page 2 of 14
FT245BM Designers Guide
Figure 1.0 is an example of a 5 volt, USB bus powered design using the FT245BM connected to a 5v MCU or
other external logic.
• In this example, we assume that the total current of the design is <= 100mA ( low power ), and that the
MCU / logic can detect USB suspend mode using either the PWREN# pin of the FT245BM and put itself
and any circuitry it is controlling into a low power state in order to meet the total USB suspend current
requirement of 500uA or less.
• RSTOUT# is used to provide a power-on reset to the external logic in this example. If the MCU has it’s
own power-on reset logic then there is usually no need to use RSTOUT# to reset the device and this
connection and the 47k pull-down can be omitted.
• The design uses two IO Ports of the MCU to communicate with the FT245BM device. One 8 bit Port is used
to transfer the data, the other port is used to control the 4 wire handshake ( RD#, WR, TXE#, RXF# ) as
required by the FT245BM device.
General Design Notes:
• PWREN# is high on power-on and only goes low ( active ) after the device has been configured (
successfully enumerated ) by USB. During USB suspend PWREN# will go high. For a high power bus
powered USB device ( 100mA .. 500mA ) you must use PWREN# for power control as no USB device is
allowed to draw more than 100mA from the bus until USB configuration is complete.
• RSTOUT# has no pull-down capability – it drives to 3.3v when not in reset, and goes tri-state during
power-on reset. If used to reset an external device, a pull-down resistor must be added to make it low
during reset.
• If the MCU is responsible for power management of the design, then connect the PWREN# pin of the
FT245BM to the MCU.
• If the design requires to wake the Host PC from USB suspend mode, then connect the SI/WU pin and
PWREN# pin to the MCU.
• If the “Send Immediate” function is required, then connect the SI/WU pin to the MCU.
• If the SI/WU pin is not required, tie it high.
• A suitable 3-pin ceramic resonator could be a Murata CSTCR6M00G15 or equivalent. See http://
www.murata.com/catalog/p63e.pdf for details If you prefer to use a 2 pin resonator or a crystal refer to
Figures 4 and 5 of the FT245BM data sheet for details.
• A suitable ferrite bead could be a Steward MI0805K400R-00 or equivalent. This is also available from
DigiKey as Part # 240-1035-1. For specifications consult the Steward web site - http://www.steward.com
DG245 Version 2.0
© Future Technology Devices Intl. Ltd. 2002 / 2003
Page 3 of 14
5
CN1
CN-USB
R8
15k
R6
10k
C3
10uF
VCC
C2
0.1uF
DECOUPLING CAPS
1
2
3
4
27R
R5
C1
0.1uF
R7
1k5
27R
R4
Y1
6MHz RESONATOR
C4
33nF
R2
2k2
VCC
© Future Technology Devices Intl. Ltd. 2002 / 2003
TEST
CS
SK
DIN
DOUT
U1
10k
R1
SI/WU
RXF#
TXE#
WR
RD#
D7
D6
D5
D4
D3
D2
D1
D0
8
7
6
5
PWREN#
VCC
NC
NC
GND
93C46/56/66
( Optional )
1
2
3
4
EEDATA
EESK
EECS
RESET#
XTOUT
XTIN
RSTOUT#
USBDP
USBDM
3V3OUT
VCC
IO16
IO17
IO20
IO21
IO22
IO23
D6
D7
RD#
WR
TXE#
RXF#
19
18
16
15
14
12
VCC
FT245BM
10
Page 4 of 14
UPDATED 21st January 2003
IO24
IO15
D5
20
PWREN#
IO14
D4
21
11
IO13
D3
22
IO12
IO11
D2
D1
24
23
IO10
D0
25
U2
FT245BM 5v SELF POWERED EXAMPLE
31
2
1
32
4
28
27
5
7
8
6
C5
0.1uF
R3
470R
VCC
3
26
13
VCC
VCC
VCC-IO
30
AVCC
AGND
29
DG245 Version 2.0
GND
GND
VCC
GND
5v MCU or Logic cct
VCC-5v
VCC
GND
EXTERNAL 5V POWER
VCC
C6
0.1uF
Figure 2.0
9
17
USB
FT245BM Designers Guide
FT245BM – 5 volt Self Powered Example Schematic ( 245-5VS )
FT245BM Designers Guide
Figure 2.0 is an example of a 5 volt, USB self powered design using the FT245BM connected to a 5v MCU or
other external logic. A USB self power design has it’s own PSU and does not draw it’s power from the USB
bus. In such a case, no special care need be taken to meet the USB suspend current ( 0.5mA ) as the device
does not get its power from the USB port.
• In this case it is still useful to connect PWREN# to the CPU as this will let the CPU know that the PC is in
suspend mode and thus unable to communicate with the device. If the device requires to “wake up” the
PC then the MCU should connect one of it’s IO Ports to the SI/WU pin of the FT245BM. The default state
of SI/WU should be high - strobing this low for a few milliseconds then taking it high again will cause a
USB resume sequence thus requesting the PC to wake up. To use this feature, Remote Wake-Up must be
enabled in the 93C46 EEPROM.
• Set the Power Control field in the 93C46 EEPROM to tell the USB Host that this is a USB self powered
device.
• Self powered designs should NOT force current back into the Host PC ( or HUB ) via the USB Port when
the said Host / Hub is powered down and the self powered device is still powered-up from it’s own
PSU. This rule includes injecting current into the powered down Host / Hub via the 1k5 pull-up on USB
D+. Failure to do this can result in unreliable operation in the field. This is an integral part of the USB
specification and applies to all USB Self Powered devices ( not just FT245BM peripherals ). In this design,
the presence of power on the host/hub USB port is used to control the RESET# pin of the FT245BM.
When the Host / Hub is powered up, RSTOUT# pulls the top end of the 1k5 resistor on USB D+ to 3.3v
nominal thus identifying the device as a full speed device to USB. When the Host / HUB powers down,
the FT245BM is reset and RSTOUT# will go low thus preventing current being injected into the Host / Hub
USB D+ line via the 1k5 resistor.
General Design Notes – See Previous Example
DG245 Version 2.0
© Future Technology Devices Intl. Ltd. 2002 / 2003
Page 5 of 14
CN1
CN-USB
5
C3
10uF
VCC
C2
0.1uF
DECOUPLING CAPS
1
2
3
4
FB1
2
C5
10nF
27R
R5
C1
0.1uF
Y1
6MHz RESONATOR
27R
VCC
R4
FERRITE BEAD
1
R6
VCC
C4
33nF
© Future Technology Devices Intl. Ltd. 2002 / 2003
31
2
1
32
4
28
27
5
7
8
6
C6
0.1uF
R3
470R
TEST
CS
SK
DIN
DOUT
U1
10k
R1
SI/WU
RXF#
TXE#
WR
RD#
D7
D6
D5
D4
D3
D2
D1
D0
8
7
6
5
PWREN#
VCC
NC
NC
GND
93C46/56/66
( Optional )
1
2
3
4
EEDATA
EESK
EECS
RESET#
XTOUT
XTIN
RSTOUT#
USBDP
USBDM
3V3OUT
VCC
IO12
IO13
IO14
IO15
IO16
IO17
IO20
IO21
IO22
IO23
D2
D3
D4
D5
D6
D7
RD#
WR
TXE#
RXF#
23
22
21
20
19
18
16
15
14
12
VCC
IO11
D1
VCC
FT245BM
10
11
IO10
D0
24
Soft Start
Circuit
C8
0.1uF
25
U2
R7
1k
IRLML6402
Q1
Page 6 of 14
WITH POWER SWITCHING
FT245BM 5v BUS POWERED EXAMPLE
R2
2k2
1k5
VCC
3
26
13
VCC
VCC
VCC-IO
30
AVCC
AGND
29
DG245 Version 2.0
GND
GND
GND
5v MCU or Logic cct
VCC-5v
C7
0.1uF
Figure 3.0
9
17
USB
FT245BM Designers Guide
FT245BM – 5v Bus Powered Schematic with Power Switching ( 245-5VSW )
FT245BM Designers Guide
Figure 3.0 is an example of a 5 volt, USB bus powered design using the FT245BM connected to a 5v MCU or
other external logic. In this design, the FT245BM controls the power to the auxiliary circuitry using PWEREN#
to shut off power to this circuitry when –
1. The FT245BM is in reset, OR
2. The FT245BM has not yet been configured ( successfully recognised and enumerated over USB ), OR
3. USB is in suspend / sleep mode.
•
•
•
•
•
A P-Channel Logic Level MOSFET is used as a power switch to control the power to the auxiliary devices
– in this example we use a International Rectifier part number IRLML6402. R7 and C8 form a “soft start”
circuit which limits the current surge when the MOSFET turns on. Without this, there is a danger that the
transient power surge of the MOSFET turning on will reset the FT245BM or the USB Host / Hub controller.
The values used allow the attached circuitry to power up with a slew rate of ~ 12.5v per millisecond, in
other words the output voltage will transitioning from GND to 5v in around 400uS.
When using this circuit, enable the “Pull-Down on Suspend” option in the EEPROM. This will ensure
minimum leakage current during sleep ( suspend ) mode by gently pulling down the FIFO interface pins of
the FT245BM pins to GND during USB suspend.
The auxiliary circuitry attached to the FT245BM device must have it’s own power-on-reset circuitry and
should NOT use RESETO# to generate a reset for this circuitry. RESETO# does not generate a reset
during USB sleep ( suspend ) when the auxiliary logic is powered-off, thus cannot be used as a reset in
this case.
A “USB High-Power Bus Powered Device” ( one that consumes more than 100mA and up to 500mA )
of current from the USB bus during normal operation must use this power control feature to remain
compliant as the USB specification does not allow a USB peripheral to draw more than 100mA of current
from the USB Bus until the device has been successfully enumerated. A “USB High-Power Bus Powered
Device” cannot be plugged into a USB Bus-Powered Hub as these can only supply 100mA per USB port.
The Power ( current ) consumption of the device is set in a field in the 93C46 EEPROM attached to the
FT245BM. A “USB High-Power Bus Powered Device” must use the 93C46 to inform the system of it’s
power requirements.
General Design Notes – See Previous Examples
DG245 Version 2.0
© Future Technology Devices Intl. Ltd. 2002 / 2003
Page 7 of 14
CN1
CN-USB
5
C3
10uF
VCC
C2
0.1uF
DECOUPLING CAPS
1
2
3
4
FB1
2
27R
27R
R5
VCC
R4
C1
0.1uF
Y1
6MHz RESONATOR
RSTOUT#
C5
10nF
FERRITE BEAD
1
R6
VCC
C4
33nF
R2
2k2
1k5
VCC
31
2
1
32
4
28
27
5
7
8
6
C6
0.1uF
R3
470R
TEST
© Future Technology Devices Intl. Ltd. 2002 / 2003
CS
SK
DIN
DOUT
U1
10k
R1
SI/WU
RXF#
TXE#
WR
RD#
D7
D6
D5
D4
D3
D2
D1
D0
8
7
6
5
PWREN#
VCC
NC
NC
GND
93C46/56/66
( Optional )
1
2
3
4
EEDATA
EESK
EECS
RESET#
XTOUT
XTIN
RSTOUT#
USBDP
USBDM
3V3OUT
VCC
30
AVCC
AGND
29
3
26
13
VCC
VCC
VCC-IO
DG245 Version 2.0
GND
GND
IO13
IO14
IO15
IO16
IO17
IO20
IO21
IO22
IO23
D4
D5
D6
D7
RD#
WR
TXE#
RXF#
21
20
19
18
16
15
14
12
VCC
FT245BM
10
RESET#
IO24
GND
UPDATED 21st January 2003
FT245BM 3.3v BUS POWERED EXAMPLE
RSTOUT#
PWREN#
IO12
D3
22
11
IO11
D2
23
VCC-3.3V
3.3v MCU or Logic cct
IO10
D1
R7
47k
C7
0.1uF
VCC-3.3V
D0
O
24
G
25
U3
U2
I
LDO REGULATOR 3.3v
Figure 4.0
9
17
USB
FT245BM Designers Guide
FT245BM – 3.3 volt Bus Powered Example Schematic ( 245-3VB )
Page 8 of 14
FT245BM Designers Guide
Figure 4.0 is an example of a 3.3 volt, USB bus powered design using the FT245BM connected to a 3.3v MCU
or other external logic.
• The main difference between this circuit and the 5 volt circuit of Figure 1.0 is that a 3.3 volt LDO regulator
i.c. is used to provide a 3.3v supply to the auxiliary circuiry.
• VCC-IO is driven from the 3.3v LDO regulator i.c. in order to drive the FIFO interface from the FT245BM to
the MCU / external logic at 3.3v level instead of 5v level.
• As the USB supply rail can drop to 4.4 volts or less under load, an LDO ( Low Dropout ) voltage regulator
must be used in this instance.
• The 3.3v LDO voltage regulator must also have a low quiescent ( no load ) current in order to ensure that
the USB suspend current requirement ( <= 500uA ) is met during USB suspend.
• In this example, we assume that the total current of the design is <= 100mA ( low power ), and that the
MCU / logic can detect USB suspend mode using the PWREN# pin of the FT245BM and put itself and
any circuitry it is controlling into a low power state in order to meet the total USB suspend current
requirement of 500uA or less.
• RSTOUT# is used to provide a power-on reset to the external logic in this example. If the MCU has it’s
own power-on reset logic then there is usually no need to use RSTOUT# to reset the device and this
connection and the 47k pull-down can be omitted. Note : If RSTOUT# is used to reset an external device
AND to pull-up the USB D+ line, it’s Vout high can be as low as 2.2v so it must be used to drive a TTL level
reset input on the external device.
General Design Notes – See Previous Examples
DG245 Version 2.0
© Future Technology Devices Intl. Ltd. 2002 / 2003
Page 9 of 14
5
CN1
CN-USB
R8
15k
R6
10k
C3
10uF
VCC
C2
0.1uF
DECOUPLING CAPS
1
2
3
4
27R
R5
C1
0.1uF
R7
1k5
27R
R4
Y1
6MHz RESONATOR
© Future Technology Devices Intl. Ltd. 2002 / 2003
R2
2k2
31
2
1
32
4
28
27
5
7
8
6
C5
0.1uF
R3
470R
TEST
CS
SK
DIN
DOUT
U1
10k
R1
SI/WU
RXF#
TXE#
WR
RD#
D7
D6
D5
D4
D3
D2
D1
D0
8
7
6
5
PWREN#
VCC
NC
NC
GND
93C46/56/66
( Optional )
1
2
3
4
EEDATA
EESK
EECS
RESET#
XTOUT
XTIN
RSTOUT#
USBDP
USBDM
3V3OUT
VCC
IO15
IO16
IO17
IO20
IO21
IO22
IO23
D6
D7
RD#
WR
TXE#
RXF#
19
18
16
15
14
12
VCC
FT245BM
10
UPDATED 21st January 2003
PWREN#
IO14
D5
20
11
IO13
D4
21
VCC-3.3V
VCC3V
VCC
IO24
VCC3V
GND
3.3v MCU or Logic cct
IO12
D3
22
IO11
D2
D1
24
23
IO10
D0
25
U2
FT245BM 3.3v SELF POWERED EXAMPLE
C4
33nF
VCC
3
26
13
VCC
VCC
VCC-IO
30
AVCC
AGND
29
DG245 Version 2.0
GND
GND
VCC 5.0v
VCC 3.3v
GND
EXTERNAL POWER
C6
0.1uF
Figure 5.0
9
17
USB
FT245BM Designers Guide
FT245BM – 3.3 volt Self Powered Example Schematic ( 245-3VS )
Page 10 of 14
FT245BM Designers Guide
Figure 5.0 is an example of a 3.3 volt, USB self powered design using the FT245BM connected to a 3.3v MCU
or other external logic. A USB self power design has it’s own PSU and does not draw it’s power from the USB
bus. In such a case, no special care need be taken to meet the USB suspend current ( 0.5mA ) as the device
does not get its power from the USB port. The differences between this circuit and that of Figure 2.0 are
minimal. See the notes in Figure 2 for the main details.
•
•
In this case the internal PSU need to supply 3.3 volts to the auxiliary circuitry and 5 volts to the FT245BM
i.c.
The VCCIO power line to the FT245BM is driven from the 3.3v supply in order to drive the auxiliary logic at
the correct voltage level.
DG245 Version 2.0
© Future Technology Devices Intl. Ltd. 2002 / 2003
Page 11 of 14
C3
10uF
C2
0.1uF
VCC
DECOUPLING CAPS
1
2
3
4
2
C5
10nF
27R
27R
VCC
C1
0.1uF
Y1
6MHz RESONATOR
R5
R4
FERRITE BEAD
FB1
R6
VCC
C4
33nF
© Future Technology Devices Intl. Ltd. 2002 / 2003
31
2
1
32
4
28
27
5
7
8
6
C6
0.1uF
R3
470R
TEST
CS
SK
DIN
DOUT
U1
10k
R1
SI/WU
RXF#
TXE#
WR
RD#
D7
D6
D5
D4
D3
D2
D1
D0
8
7
6
5
PWREN#
VCC
NC
NC
GND
93C46/56/66
( Optional )
1
2
3
4
EEDATA
EESK
EECS
RESET#
XTOUT
XTIN
RSTOUT#
USBDP
USBDM
3V3OUT
VCC
Vo
G Vi
REG1
TC55RP3302
IO14
IO15
IO16
IO17
IO20
IO21
IO22
IO23
D5
D6
D7
RD#
WR
TXE#
RXF#
20
19
18
16
15
14
12
VCC
FT245BM
10
11
IO13
D4
21
WITH POWER SWITCHING
VCC-3.3v
GND
3.3v MCU or Logic cct
IO12
D3
22
IO11
D2
23
IO10
D1
Soft Start
Circuit
D0
R7
1k
C8
0.1uF
24
C9
0.1uF
IRLML6402
Q1
25
U2
FT245BM 3.3v BUS POWERED EXAMPLE
R2
2k2
1k5
VCC
1
CN1
CN-USB
5
2
1
30
AVCC
AGND
3
26
13
VCC
VCC
VCC-IO
29
DG245 Version 2.0
GND
GND
C7
0.1uF
Figure 6.0
9
17
3
USB
FT245BM Designers Guide
FT245BM – 3.3v Bus Powered Schematic with Power Switching ( 245-3VSW )
Page 12 of 14
FT245BM Designers Guide
Figure 6.0 is an example of a 3.3 volt, USB bus powered design with power switching using the FT245BM
connected to a 3.3v MCU or other external logic. The circuit is essentially a combination of the schematics of
Figure 3 and Figure 4.
• A 3.3 volt LDO regulator i.c. is used to provide a 3.3v VCCIO rail and switched 3.3v supply to the auxiliary
circuiry via a IRLML6402 P-Channel MOSFET .
• In this example, we use a Telcom / MicroChip TC55RP3302 as the 3.3v LDO regulator. This has a maximum
rated output current of 250mA. If a higher current is required, use an LD1117 / LM1117 series LDO
regulator instead as these are rated to 800mA. The two are not pin compatible.
• R7 and C10 form a soft start circuit which helps prevent excesssive power switching transients when the
MOSFET turns on. We would advise you to include these components as without them the current surge
when the IRLML6402 MOSFET initially turns on can be capable of resetting the FT245BM or tripping the
power sense circuitry in a USB hub.
General Design Notes – See Previous Examples
DG245 Version 2.0
© Future Technology Devices Intl. Ltd. 2002 / 2003
Page 13 of 14
FT245BM Designers Guide
Document Revision History
DG245B Version 1.0 –
DG245B Version 2.0 •
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Initial document created 09 August 2002
Created 19th May 2003
Corrected Pull Up Control Circuit for Self Powered Designs
Corrected connection of PWRCTL in 3.3v Self Powered Designs
Updated Schematic Drawings
Added 3.3v Switched Bus Powered reference schematic
Disclaimer
© Future Technology Devices International Limited , 2002 / 2003
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 product. 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.
The information in this document may be subject to change without notice..
Contact Information
Future Technology Devices Intl. Limited
St. George’s Studios
93/97 St. George’s Road,
Glasgow G3 6JA,
United Kingdom.
Tel : +44 ( 0 )141 353 2565
Fax : +44 ( 0 )141 353 2656
E-Mail ( Sales ) : [email protected]
E-Mail ( Support ) : [email protected]
E-Mail ( General Enquiries ) : [email protected]
Web Site URL : http://www.ftdichip.com
Agents and Sales Representatives
At the time of writing our Sales Network covers over 50 different countries world-wide. Please visit the Sales Network
page of our Web Site site for the contact details our distributor(s) in your country.
DG245 Version 2.0
© Future Technology Devices Intl. Ltd. 2002 / 2003
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