Datasheet
DS80C310 
15 of 22 
Note 2: 
Address is held in a weak latch until overdriven by external memory. 
EXTERNAL CLOCK CHARACTERISTICS 
PARAMETER SYMBOL MIN TYP MAX UNITS 
Clock High Time  t
CHCX 
10   ns 
Clock Low Time  t
CLCX 
10   ns 
Clock Rise Time  t
CLCL 
 5 ns 
Clock Fall Time  t
CHCL 
 5 ns 
SERIAL PORT MODE 0 TIMING CHARACTERISTICS 
PARAMETER SYMBOL  CONDITIONS  MIN TYP MAX UNITS 
SM2 = 0, 12 clocks per cycle    12t
CLCL 
Serial Port Clock Cycle 
Time 
t
XLXL 
SM2 = 1, 4 clocks per cycle    4t
CLCL 
ns 
SM2 = 0, 12 clocks per cycle    10t
CLCL 
Output Data Setup to 
Clock Rising 
t
QVXH 
SM2 = 1, 4 clocks per cycle    3t
CLCL 
ns 
SM2 = 0, 12 clocks per cycle    2t
CLCL 
Output Data Hold from 
Clock Rising 
t
XHQX 
SM2 = 1, 4 clocks per cycle    t
CLCL 
ns 
SM2 = 0, 12 clocks per cycle    t
CLCL 
Input Data Hold after 
Clock Rising 
t
XHDX 
SM2 = 1, 4 clocks per cycle    t
CLCL 
ns 
SM2 = 0, 12 clocks per cycle    11t
CLCL 
Clock Rising Edge to 
Input Data Valid 
t
XHDV 
SM2 = 1, 4 clocks per cycle    3t
CLCL 
ns 
DEFINITION OF AC SYMBOLS 
In an effort to remain compatible with the original 8051 family, this device specifies the same parameters 
as such devices, using the same symbols. For completeness, the following are description of the symbols. 
t  Time 
A  Address 
C  Clock 
D  Input Data 
H  Logic Level High 
L  Logic Level Low 
I  Instruction 
P 
PSEN
Q  Output Data 
R 
RD
Signal 
V  Valid 
W 
WR
 Signal 
X  No longer a valid logic level 
Z  Tri-State 










