Datasheet

380
2549O–AVR–05/12
ATmega640/1280/1281/2560/2561
Table 31-12. External Data Memory Characteristics, 4.5 to 5.5 Volts, 1 Cycle Wait-state
Symbol Parameter
8MHz Oscillator Variable Oscillator
UnitMin Max Min Max
01/t
CLCL
Oscillator Frequency 0.0 16 MHz
10 t
RLDV
Read Low to Data Valid 200 2.0t
CLCL
-50
ns
12 t
RLRH
RD Pulse Width 240 2.0t
CLCL
-10
15 t
DVWH
Data Valid to WR High 240 2.0t
CLCL
16 t
WLWH
WR Pulse Width 240 2.0t
CLCL
-10
Table 31-13. External Data Memory Characteristics, 4.5 to 5.5 Volts, SRWn1 = 1, SRWn0 = 0
Symbol Parameter
4MHz Oscillator Variable Oscillator
UnitMin Max Min Max
01/t
CLCL
Oscillator Frequency 0.0 16 MHz
10 t
RLDV
Read Low to Data Valid 325 3.0t
CLCL
-50
ns
12 t
RLRH
RD Pulse Width 365 3.0t
CLCL
-10
15 t
DVWH
Data Valid to WR High 375 3.0t
CLCL
16 t
WLWH
WR Pulse Width 365 3.0t
CLCL
-10
Table 31-14. External Data Memory Characteristics, 4.5 to 5.5 Volts, SRWn1 = 1, SRWn0 = 1
Symbol Parameter
4MHz Oscillator Variable Oscillator
UnitMin Max Min Max
01/t
CLCL
Oscillator Frequency 0.0 16 MHz
10 t
RLDV
Read Low to Data Valid 325 3.0t
CLCL
-50
ns
12 t
RLRH
RD Pulse Width 365 3.0t
CLCL
-10
14 t
WHDX
Data Hold After WR High 240 2.0t
CLCL
-10
15 t
DVWH
Data Valid to WR High 375 3.0t
CLCL
16 t
WLWH
WR Pulse Width 365 3.0t
CLCL
-10
Table 31-15. External Data Memory Characteristics, 2.7 to 5.5 Volts, No Wait-state
Symbol Parameter
4MHz Oscillator Variable Oscillator
UnitMin Max Min Max
01/t
CLCL
Oscillator Frequency 0.0 8 MHz