DS_FT2232D Datasheet, PDF (29/61 Pages) List of Unclassifed Manufacturers – Future Technology Devices International Ltd

Document No.: FT_000173
FT2232D DUAL USB TO SERIAL UART/FIFO IC Datasheet
Version 2.05
Clearance No.: FTDI# 127
7.1 EEPROM Configurations
Figure 7.3 EEPROM Configuration
Figure 7.3 illustrates how to connect the FT2232D to the 93C46 (93C56 or 93C66) EEPROM. EECS (pin
48) is directly connected to the chip select (CS) pin of the EEPROM. EESK (pin 1) is directly connected to
the clock (SK) pin of the EEPROM. EEDATA (pin 2) is directly connected to the Data In (Din) pin of the
EEPROM. There is a potential condition whereby both the Data Output (Dout) of the EEPROM can drive
out at the same time as the EEDATA pin of the FT2232D. To prevent potential data clash in this situation,
the Dout of the EEPROM is connected to EEDATA of the FT2232D via a 2.2K resistor.
Following a power-on reset or a USB reset, the FT2232D will scan the EEPROM to find out (a) if an
EEPROM is attached to the Device and (b) if the data in the device is valid. If both of these are the case,
then the FT2232D will use the data in the EEPROM, otherwise it will use its built-in default values and
configuration. The default port configuration of the FT2232D puts both Channel A and Channel B into
serial UART mode.
When a valid command is issued to the EEPROM from the FT2232D, the EEPROM will acknowledge the
command by pulling its Dout pin low. In order to check for this condition, it is necessary to pull Dout high
using a 10K resistor. If the command acknowledge doesn‟t happen then EEDATA will be pulled high by
the 10K resistor during this part of the cycle and the device will detect an invalid command or no EEPROM
present.
There are two varieties of 93C46/56/66 EEPROM‟s on the market – one is configured as being 16 bits
wide, the other is configured as being 8 bits wide. These are available from many sources such as
Microchip, STMicro, ISSI etc. The FT2232D requires EEPROM‟s with a 16-bit wide configuration such as
the Microchip 93LC46B device. The EEPROM must be capable of reading data at a 1Mb clock rate at a
supply voltage of 4.35V to 5.25V. Most available parts are capable of this. Check the manufacturers data
sheet to find out how to connect pins 6 and 7 of the EEPROM. Some devices specify these as no-connect,
others use them for selecting 8 / 16 bit mode or for test functions. Some other parts have their pinout
rotated by 90o so please select the required part and its options carefully.
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