ft8u245am Future Technology Devices International Ltd., ft8u245am Datasheet - Page 3

• Manufacturer Part Number: ft8u245am
• Description: Usb Fifo - Fast Parallel Data Transfer Ic
• Manufacturer: Future Technology Devices International Ltd.

FT8U245AM - FUNCTIONAL BLOCK DESCRIPTION
3.3V LDO Regulator
The 3.3V LDO Regulator generates the 3.3 volt reference voltage for driving the USB transceiver cell
output buffers. It requires an external decoupling capacitor to be attached to the 3V3OUT regulator
output pin.
USB Transceiver
The USB Transceiver Cell provides the USB 1.1 full-speed physical interface to the USB cable. The
output drivers provide 3.3 volt level slew rate control signalling, whilst a differential receiver and two single
ended receivers provide USB data in, SEO and USB Reset condition detection.
USB DPLL
The USB DPLL cell locks on to the incoming NRZI USB data and provides separate recovered clock and
data signals to the SIE block.
6MHz Oscillator
The 6MHz Oscillator cell generates a 6MHz reference clock input to the X8 Clock multiplier from an
external 6MHz crystal or ceramic resonator.
X8 Clock Multiplier
The X8 Clock Multiplier takes the 6MHz input from the Oscillator cell and generates a 12MHz reference
clock for the SIE, USB Protocol Engine and UART FIFO controller blocks. It also generates a 48MHz
reference clock for the USB DPPL and the Baud Rate Generator blocks.
Serial Interface Engine ( SIE )
The Serial Interface Engine ( SIE ) block performs the Parallel to Serial and Serial to Parallel conversion
of the USB data. In accordance to the USB 1.1 specification, it performs bit stuffing / un-stuffing and
CRC5 / CRC16 generation / checking on the USB data stream.
USB Protocol Engine
The USB Protocol Engine manages the data stream from the device USB control endpoint. It handles the
low level USB protocol ( Chapter 9 ) requests generated by the USB host controller and the commands
for controlling the functional parameters of the UART.
Fifo Receive Buffer ( 128 bytes )
Data sent from the USB Host to the FIFO via the USB data out endpoint is stored in the FIFO Receive
Buffer and is removed from the buffer by reading the FIFO contents using RD#.
Future Technology Devices Intl.
FT8U245AM Preliminary Information Rev 0.9 – Subject to Change