Rainbow Electronics AT90S8515 - Manual (Page 92)

92
AT90S8515
0841G–09/01
External Clock Drive
Waveforms Figure 67. External Clock
Note: See “External Data Memory Timing” for a description of how the duty cycle influences the
timing for the external data memory.
Figure 68. External RAM Timing
Table 36. External Clock Drive
Symbol Parameter
V
CC
= 2.7V to 4.0V V
CC
= 4.0V to 6.0V
Units Min Max Min Max
1/t
CLCL
Oscillator Frequency 0 4.0 0 8.0 MHz
t
CLCL
Clock Period 250.0 125.0 ns
t
CHCX
High Time 100.0 50.0 ns
t
CLCX
Low Time 100.0 50.0 ns
t
CLCH
Rise Time 1.6 0.5 µs
t
CHCL
Fall Time 1.6 0.5 µs
VIL1
VIH1
System Clock Ø
ALE
WR
RD
Data/Address [7..0]
Data/Address [7..0]
Address [15..8]
Address
Address
Address
T1 T2 T3 T4
Prev. Address
Prev. Address
Prev. Address
1
0
4
2 13
3a
5
Note: Clock cycle T3 is only present when external SRAM wait state is enabled.
10
12
14
15
11
8
9
16
7
6
3b
Data
Data
Wr
ite
Read
Addr.
Addr.