Though the FT232BM will work without the optional EEPROM, an external 93C46 (93C56 or 93C66) EEPROM can be used to customise the
USB VID, PID, Serial Number, Product Description Strings and Power Descriptor value of the FT232BM 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 available from FTDI’s web site (
http://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 FT232BM will 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.
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