Document No.: FT_000061
FT2232H DUAL HIGH SPEED USB TO MULTIPURPOSE UART/FIFO IC
Datasheet Version 2.09
Clearance No.: FTDI#77
4.3.2 Dual Port RS422 Configuration
Figure 4.2 illustrates how the FT2232H can be configured as a dual RS422 interface.
VCC
FT2232H
DB9-M
RS422 Channel A
14 SP491
60
36
4
PWREN#
10
9
TXDM_A
SUSPEND#
TXD
5
3
2
D
TXDP_A
RXDP_A
16
17
18
19
21
22
23
24
26
11
120R
R
12
RXD
RXDM_A
6
7
RTS#
CTS#
DTR#
DSR#
DCD#
RI#
VCC
14 SP491
GND
4
10
9
RTSM_A
5
3
2
D
RTSP_A
CTSP_A
11
120R
R
12
CTSM_A
6
7
TXDEN
VCC
DB9-M
RS422 Channel B
14 SP491
4
10
9
TXDM_B
5
3
2
D
38
39
40
41
43
44
45
46
48
TXDP_B
RXDP_B
TXD
RXD
11
120R
R
12
RTS#
CTS#
DTR#
DSR#
DCD#
RI#
RXDM_B
6
7
VCC
14 SP491
GND
4
10
9
RTSM_B
5
3
2
D
RTSP_B
CTSP_B
11
120R
R
12
CTSM_B
TXDEN
6
7
Figure 4.2 Dual RS422 Configuration
In this case both channel A and channel B are configured as UART operating at TTL levels. The Sipex
SP491 is used as a level converter to convert the TTL level signals from the FT2232H to RS422 levels.
The PWREN# signal is used to power down the level shifters such that they operate in a low quiescent
current when the USB interface is in suspend mode.
Copyright © 2010 Future Technology Devices International Limited
22
FTDI [ FUTURE TECHNOLOGY DEVICES INTERNATIONAL LTD. ]
