Document No.: FT_000061
FT2232H DUAL HIGH SPEED USB TO MULTIPURPOSE UART/FIFO IC
Datasheet Version 2.09
Clearance No.: FTDI#77
4.8.3 Fast Opto-Isolated Serial Data Interface Example
The following example,Figure 4.16 , shows two Agilent HCPL-2430 (see the semiconductor section at
www.agilent.com) high speed opto-couplers used to optically isolate an external device which
interfaced to USB using the FT2232H. In this example VCC5V is the USB VBUS supply and VCCE is the
supply to the external device.
Care must be taken with the voltage used to power the photo-LED‟s. It must be the same voltage as that
the FT2232H I/Os are driving to, or the LED‟s may be permanently on. Limiting resistors should be fitted
in the lines that drive the diodes. The outputs of the opto-couplers are open-collector and require a pull-
up resistor.
VCC5V
Cable
VCCE
FT2232H
8
1
2
HCPL-2430
1K
1K
7
470R
470R
FSDI
DI
3
6
5
CLK
FSCLK
4
VCCE
VCC5V
8
1
HCPL-2430
1K
1K
7
470R
470R
2
3
FSDO
DO
FSCTS
6
5
CTS
4
Figure 4.16 Fast Opto-Isolated Serial Interface Example
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