User`s guide

LZ87010 Advance User’s Guide System Clocking
1/15/03 2-5
2.2 Signals
Table 2-1 details the system clocking signals.
Table 2-1. System Clock Signals
SIGNAL
NAME
SIGNAL
TYPE
PIN
NO.
PIN
TYPE
FUNCTIONAL
UNIT
DESCRIPTION
XTAL_SUB1 I 72 I/O Clock
Subclock Crystal When a 32.768 kHz crystal is
used, this pin connects to one of the crystal pins.
When an external clock generator is used, this pin
is the clock input. If the subclock is not needed, this
pin should be tied to VDD.
XTAL_SUB2 O 73 I/O Clock
Subclock Crystal When a 32.768 kHz crystal is
used, this pin connects to one of the crystal pins.
Otherwise, this pin is tied to VSS.
XTAL1 I 74 I/O Clock
System Crystal When a 20-40 MHz crystal is used
for the high-frequency system oscillator, this signal
connects to one of the crystal pins. When an external
clock generator is used, this pin is the clock input.
XTAL2 O 75 I/O Clock
System Crystal When a 20-40 MHz crystal is used
for the high-frequency system oscillator, this signal
connects to one of the crystal pins. When an external
clock generator is used, this pin connects to VSS.