COM20020_00 Datasheet, PDF (74/82 Pages) SMSC Corporation – Universal Local Area Network Controller with 2K x 8 On-Board RAM

XTAL1
4.0V
t1
t2
1.0V
t3
50% of VDD
Parameter
t1
Input Clock High Time
t2
Input Clock Low Time
t3
Input Clock Period
t4
Input Clock Frequency
t5
Frequency Accuracy*
min typ max units
10
nS
10
nS
25
100 ^nS
10
40 MHz
-200
200 ppm
Note*: Input clock frequency must be 20 MHz (+- 100ppm or better) to use the internal Clock Multiplier.
t5 is applied to crystal oscillaton.
FIGURE 21 – TTL INPUT TIMING ON XTAL1 PIN
t1
nRESET
nINTR
t2
Parameter
min typ
t1
nRESET Pulse Width***
t2
nINTR High to Next nINTR Low EF = 0
EF = 1
5TXTL^*
TDR**/2
4TXTL*
Note*: TXTL is period of external XTAL oscillation frequency.
Note**: TDR is period of Data Rate (i.e. at 2.5 Mbps, TDR = 400 nS)
Note***: When the power is turned on, t1 is measured from stable XTAL
oscillation after VDD was over 4.5V.
FIGURE 22 – RESET AND INTERRUPT TIMING
max units
74
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