FT900 datasheet(44/58 Pages) FTDI

Part #	FT900

Description	The FT900 series includes the FT900,FT901, FT902 and FT903 which are complete System-On-Chip 32-bit RISC microcontrollers for embedded applications featuring a high level of integration and low powerconsumption

PDF	58 Pages

Scroll/Zoom	100%

Manufacturer	FTDI [Future Technology Devices International Ltd.]

Direct Link	http://www.ftdichip.com

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44 / 58 page

FT900/1/2/3 Embedded Microcontroller Datasheet

Version 1.0

Document No.: FT_000965 Clearance No.: FTDI#421

6 Application Information

6.1

Crystal Oscillator

The crystal oscillator operates at a frequency of 12MHz. The oscillator can operate one of two

following configuration.

6.1.1 Crystal oscillator application circuit

FT900

XI/CLKIN

XIO

XTAL

12MHz

Figure 6-1 Crystal oscillator connection

Since the feedback resistance is integrated on chip, only a crystal and capacitors CL need to be

connected externally. With the proper selection of crystal, the oscillator circuit can generate

better quality signals for FT900. Parameter CL is typically 27pF but should be checked with the

crystal manufacturer.

6.1.2 External clock input

FT900

XI/CLKIN

XIO

12MHz

Figure 6-2 External clock input

The 12MHz input clock signal connects XI/CLKIN to internal oscillator directly. The XIO pin can

be left unconnected.

6.2

RTC Oscillator

In the RTC oscillator circuit Figure 6-3, only a 32.768 KHz crystal and capacitors CRTCL need to

be connected externally. The parameter CRTCL should be checked with the crystal manufacturer.

An external input clock Figure 6-4 can be connected to RTC_XI/RTC_CLKIN if RTC_XIO is left

open.

FT900 Datasheet(PDF) 44 Page - Future Technology Devices International Ltd.