at94k40al ATMEL Corporation, at94k40al Datasheet - Page 42

• Manufacturer Part Number: at94k40al
• Description: At94kal Series Field Programmable System Level Integrated Circuit
• Manufacturer: ATMEL Corporation

4.4.2
4.4.3
4.4.4
42
AT94KAL Series FPSLIC
External Clock
No Clock/Oscillator Source
Timer Oscillator
To drive the device from an external clock source, XTAL2 should be left unconnected while
XTAL1 is driven as shown in
Figure 4-2.
When not in use, for low static IDD, add a pull-down resistor to XTAL1.
Figure 4-3.
For the timer oscillator pins, TOSC1 and TOSC2, the crystal is connected directly between the
pins. The oscillator is optimized for use with a 32.768 kHz watch crystal. An external clock signal
applied to this pin goes through the same amplifier having a bandwidth of 1 MHz. The external
clock signal should therefore be in the range
0 Hz – 1 MHz.
Figure 4-4.
External Clock Drive Configuration
No Clock/Oscillator Connections
Time Oscillator Connections
C
C
R
1
2
PD
Figure
NC
OSCILLATOR
EXTERNAL
4-2.
SIGNAL
R
NC
XTAL2
XTAL1
GND
B
R
S
TOSC2
TOSC1
R
XTAL2
XTAL1
GND
PD
= 4.7 KΩ
C
C
R
R
1
2
B
S
= 33 pF
= 27 pF
= 10M
= 200K
1138I–FPSLI–1/08