FT245BL-REEL FTDI, Future Technology Devices International Ltd, FT245BL-REEL Datasheet - Page 15

• Manufacturer Part Number: FT245BL-REEL
• Description: IC USB TO PARALLEL
• Manufacturer: FTDI, Future Technology Devices International Ltd

Specifications of FT245BL-REEL

• Applications: USB to FIFO Controller
• Interface: USB, 8bit FIFO (Sync/Async)
• Voltage - Supply: 4.35 V ~ 5.25 V
• Package / Case: 32-LQFP
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3-Pin Resonator
7.0
7.1
Figure 4
3 Pin Ceramic Resonator Configuration
Figure 4 illustrates how to use the FT245BL with a 3-Pin Ceramic Resonator. A suitable part would be a ceramic
resonator from Murata’s CERALOCK range. (Murata Part Number CSTCR6M00G15), or equivalent. 3-Pin ceramic
resonators have the load capacitors built into the resonator so no external loading capacitors are required. This
makes for an economical configuration. The accuracy of this Murata ceramic resonator is +/- 0.1% and it is specifically
designed for USB full speed applications. A 1 MOhm loading resistor across XTIN and XTOUT is recommended in
order to guarantee this level of accuracy.
Other ceramic resonators with a lesser degree of accuracy ( typically +/- 0.5% ) are technically outwith the USB
specification, but it has been calculated that using such a device will work satisfactorily in practice with a FT245BL
design.
Figure 5 illustrates how to use the FT245BL with a 6MHz Crystal or 2-Pin Ceramic Resonator. In this case, these
devices do not have in-built loading capacitors so these have to be added between XTIN, XTOUT and GND as
shown. A value of 27pF is shown as the capacitor in the example – this will be good for many crystals and some
resonators but do select the value based on the manufacturers recommendations wherever possible. If using a crystal,
use a parallel cut type. If using a resonator, see the previous note on frequency accuracy.
6MHz
DS245BL Version 1.7
Device Configuration Examples
Oscillator Configurations
1M
27
28
© Future Technology Devices Intl. Ltd. 2005
XTIN
XTOUT
FT245BL
FT245BM
2 - Pin Resonator
Figure 5
Crystal or 2-Pin Ceramic Resonator
Configuration
or Crystal
6MHz
FT245BL USB FIFO ( USB - Parallel ) I.C.
27pF
27pF
27
28
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XTIN
XTOUT
FT245BM
FT245BL
FT24