afs600 Actel Corporation, afs600 Datasheet - Page 35

• Manufacturer Part Number: afs600
• Description: Actel Fusion Programmable System Chips Mixed-signal Family With Optional Arm Support
• Manufacturer: Actel Corporation

In Modes 1 to 3, the crystal oscillator is configured to
support an external crystal or ceramic resonator. These
modes correspond to low, medium, and high gain. They
differ in the crystal or resonator frequency supported.
The crystal or resonator is connected to the XTAL1 and
XTAL2 pins. Additionally, a capacitor is required on both
XTAL1 and XTAL2 pins to ground
page
oscillator mode, supported frequency range, and
recommended capacitor value.
A use model supported by the Fusion device involves
powering down the core while the RTC continues to run,
clocked by the crystal oscillator. When powered down,
Crystal Oscillator Characteristics
Table 2-11 • Electrical Characteristics of the Crystal Oscillator
Parameter
F
I
I
PSRR
V
V
DYNXTAL
STBXTAL
XTAL
IHXTAL
ILXTAL
XTAL
2-18).
Table 2-10 on page 2-20
Operating Frequency
Output Duty Cycle
Output Jitter
Operating Current
Sleep Current
Power Supply Noise Tolerance
Input Logic Level HIGH
Input Logic Level LOW
Description
details each crystal
(Figure 2-16 on
Using External Crystal
Using Ceramic Resonator
Using RC Network
With 10 MHz Crystal
RC
0.032–0.2 MHz
0.2–2.0 MHz
2.0–20.0 MHz
Conditions
A d v an c ed v1 . 4
the core cannot control crystal oscillator mode pins. Also,
some designers may wish to avoid the RTC altogether. To
support both situations, the crystal oscillator can be
controlled by either the RTC or the FPGA core. If the RTC
is instantiated in the design, it will by default use
RTCMODE[1:0] to set the crystal oscillator control pins
(the default). If the RTC is not used in the design, the
FPGA core will set the crystal oscillator control pins with
MODE[1:0].
The crystal oscillator can be disabled/enabled by RTC or
FPGA upon operation requirement. When the crystal
oscillator is disabled, XTL1 and XTL2 pins can be left
floating.
90% of V
0.032
0.032
Min.
0.5
Actel Fusion Programmable System Chips
CC
Typ.
0.19
0.6
0.6
0.6
0.5
50
50
10
10% of V
Max.
20
8
4
CC
ps RMS
Units
Vp–p
MHz
MHz
MHz
mA
mA
mA
mA
µA
%
V
V
2-21