FT2232C Dual USB UART / FIFO I.C.
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EEPROM Interface
When used without an external EEPROM the
FT2232C be configured as a USB to dual serial
port device. Adding an external 93C46 (93C56
or 93C66) EEPROM allows each of the chip’s
channels to be independently configured as a
serial UART (232 mode), or a parallel FIFO (245
mode). The external EEPROM is used to enable
the CPU-style FIFO interface, and Fast Opto-
Isolated Serial interface modes. The external
EEPROM can also be used to customise the USB
VID, PID, Serial Number, Product Description
Strings and Power Descriptor value of the
FT2232C for OEM applications. Other parameters
controlled by the EEPROM include Remote Wake
Up, Isochronous Transfer Mode, Soft Pull Down on
Power-Off and USB 2.0 descriptor modes.
The EEPROM should be a 16 bit wide
configuration such as a MicroChip 93LC46B or
equivalent capable of a 1Mb/s clock rate at VCC =
4.35V to 5.25V. The EEPROM is programmable-
on board over USB using a utility program available
from FTDI’s web site (www.ftdichip.com). This
allows a blank part to be soldered onto the PCB
and programmed as part of the manufacturing and
test process.
If no EEPROM is connected (or the EEPROM
is blank), the FT2232C will default to dual serial
ports. The device use its built-in default VID, PID
Product Description and Power Descriptor Value.
In this case, the device will not have a serial
number as part of the USB descriptor.
DS2232C Version 1.2
© Future Technology Devices International Ltd. 2004
Page 8 of 54
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