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
FT2232H
60
PWREN#
SUSPEND#
TXD
RXD
RTS#
CTS#
DTR#
DSR#
DCD#
RI#
TXDEN
36
5
D
4
VCC
14 SP491
10
9
11
DB9-M
RS422 Channel A
TXDM_A
TXDP_A
RXDP_A
120R
RXDM_A
16
17
18
19
21
22
23
24
26
3
2
R
6
7
VCC
14 SP491
4
10
5
3
11
2
R
6
7
VCC
14 SP491
4
10
5
12
120R
D
9
12
GND
RTSM_A
RTSP_A
CTSP_A
CTSM_A
DB9-M
RS422 Channel B
TXDM_B
TXDP_B
RXDP_B
120R
RXDM_B
38
TXD
39
RXD
40
RTS#
41
CTS#
43
DTR#
44
DSR#
45
DCD#
46
RI#
48
TXDEN
6
5
3
4
6
2
3
D
9
11
R
7
VCC
14 SP491
10
12
GND
RTSM_B
RTSP_B
CTSP_B
120R
CTSM_B
D
9
11
2
R
7
12
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.
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22
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