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Using the STK594 Top Module
2-6 FPSLIC STK594 User Guide
2819A–FPSLI–07/02
2.9 Split Power
Supply Support
The AT94K FPSLIC devices exist in two different variations, the AL and AX. The AL
variation is a 3.3V device manufactured on a 0.35µ process, while the AX variation has
a 1.8V core manufactured on a 0.18µ process. The primary difference between the two
variations, is that the AX device requires a split power supply, as the I/Os are still pow-
ered from a 3.3V supply, while the core operates at 1.8V.
The STK594 supports both AT94K variations. If an AX variant is being used it is neces-
sary to supply the proper core to the AT94K device. Figure 2-11 shows how to set the
jumper to select the core voltage.
Figure 2-11.
AT94K Core Voltage Selector
2.10 XTAL Switch An oscillator is included on the STK594 for supplying an additional clock to the AT94K
FPSLIC device. The XTAL switch selects if the oscillator is connected to the XTAL1 pin,
or whether the clock is provided by the STK500.
Figure 2-12 shows a simplified block schematic on how this is implemented.
Figure 2-12.
XTAL Block Schematic
2.11 Reset Switches The reset switch found on the STK594 is connected to the AT94K’s RESET pin. When
pressed, the AT94K device will reset and initiate a configuration download from the con-
figuration memory.
The reset switch found on the STK500 is connected to the AVRRESET
. When pressed,
the embedded AVR microcontroller resets and begins execution at location $0000.
AL
AX
AT94KAX
AL
AX
AT94KAL
VDD
VDD
XTAL2
XTAL1
XT1
FPSLIC
XT2
OSC