Document No.: FT_000060
FT4232H QUAD HIGH SPEED USB TO MULTIPURPOSE UART/MPSSE IC
Datasheet Version 2.09
Clearance No.: FTDI#78
6.3 Oscillator Configuration
FT4232H
27pF
2
OSCI
12MHz
Crystal
27pF
3
OSCO
Figure 6.5 Recommended FT4232H Crystal Oscillator Configuration.
Figure 6.5 illustrates how to connect the FT4232H with a 12MHz ± 0.003% crystal. In this case loading
capacitors should to be added between OSCI, OSCO and GND as shown. A value of 27pF is shown as the
capacitor in the example – this will be good for many crystals but it is recommended to select the loading
capacitor value based on the manufacturer’s recommendations wherever possible. It is recommended to
use a parallel cut type crystal.
It is also possible to use a 12 MHz oscillator with the FT4232H. In this case the output of the oscillator
would drive OSCI, and OSCO should be left unconnected. The oscillator must have a CMOS output drive
capability.
Parameter
Description
Minimum
Typical
Maximum
Units
Conditions
OSCI Vin
Input Voltage
Input Frequency
Cycle to cycle jitter
2.97
3.30
12
3.63
V
FIn
MHz
pS
+/- 30ppm
Ji
< 150
Table 6.1 OSCI Input characteristics
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