80296SA COMMERCIAL CHMOS 16-BIT MICROCONTROLLER
6.2.7 EXTERNAL CLOCK DRIVE
Table 14. External Clock Drive
Symbol
Parameter
Min
Max
Units
FXTAL1 External Input Frequency (1/TXLXL), PLL disabled
16
50†
MHz
External Input Frequency (1/TXLXL), PLL in 2x mode
8
25
MHz
External Input Frequency (1/TXLXL), PLL in 4x mode
8
12.5
MHz
TXTAL1
Oscillator Period (TXLXL), PLL disabled
20
62.5
ns
Oscillator Period (TXLXL), PLL in 2x mode
40
125
ns
Oscillator Period (TXLXL), PLL in 4x mode
80
125
ns
TXHXX
High Time
0.35TXTAL1 0.65TXTAL1
ns
TXLXX
Low Time
0.35TXTAL1 0.65TXTAL1
ns
TXLXH
Rise Time
10
ns
TXHXL
Fall Time
10
ns
† Assumes an external clock; the maximum input frequency for an external crystal oscillator is 25 MHz.
XTAL1
TXHXX
0.7 VCC + 0.5 V
TXLXH
TXLXX
0.3 VCC – 0.5 V
0.7 VCC + 0.5 V
0.3 VCC – 0.5 V
TXLXL
Figure 13. External Clock Drive Waveforms
TXHXL
A2119-03
PRELIMINARY
31