Data Sheet ADuM1240/ADuM1241/ADuM1245/ADuM1246
Rev. B | Page 13 of 24
TRUTH TABLES
Table 22 provides the truth table (positive logic) for the
ADuM1240 and the ADuM1241, and Table 23 provides the
truth table (positive logic) for the ADuM1245 and the
ADuM1246. For a description of the abbreviations used in the
truth tables, see Table 21.
Table 21. Truth Table Abbreviations
Letter Description
H High level
L Low level
↑
Rising data transition
↓
Falling data transition
X Irrelevant
Q
O
Level of V
OX
prior to levels being established
Z High impedance
Table 22. ADuM1240/ADuM1241 Truth Table (Positive Logic)
1, 2, 3
V
Ix
Input V
DDI
State V
DDO
State
EN
x
State
V
Ox
Output Description
H Powered Powered L H Normal operation; data is high and refresh is enabled.
L Powered Powered L L Normal operation; data is low and refresh is enabled.
X Unpowered Powered L H Input unpowered. Outputs are in the default high state. Outputs return to
the input state within 150 µs of V
DDI
power restoration. See the pin function
descriptions (Table 19 and Table 20) for details.
X Unpowered Powered H Q
O
Input unpowered. Outputs are static at the level that was last sent from
the input or at the power-up level. See the pin function descriptions (Table 19
and Table 20) for details.
Powered Powered H H Output is high after propagation delay, refresh is disabled.
Powered Powered H L Output is low after propagation delay, refresh is disabled.
X Powered Unpowered X Z Output unpowered. Output pins are in high impedance state. Outputs
return to the input state within 150 µs of V
DDO
power restoration. See the
pin function descriptions (Table 19 and Table 20) for details.
1
V
Ix
and V
Ox
refer to the input and output signals of a given channel (A, B, C, or D).
2
V
DDI
refers to the power supply on the input side of a given channel (A, B, C, or D).
3
V
DDO
refers to the power supply on the output side of a given channel (A, B, C, or D).
Table 23. ADuM1245/ADuM1246 Truth Table (Positive Logic)
1, 2, 3
V
Ix
Input V
DDI
State V
DDO
State EN
x
State V
Ox
Output Description
H Powered Powered L H Normal operation; data is high and refresh is enabled.
L Powered Powered L L Normal operation; data is low and refresh is enabled.
X Unpowered Powered L L Input unpowered. Outputs are in the default low state. Outputs
return to the input state within 150 µs of V
DDI
power restoration. See
the pin function descriptions (Table 19 and Table 20) for details.
X Unpowered Powered H Q
O
Input unpowered. Outputs are static at the level that was last sent
from the input or at the power-up level. See the pin function
descriptions (Table 19 and Table 20) for details.
Powered Powered H H Output is high, refresh is disabled.
Powered Powered H L Output is low, refresh is disabled.
X Powered Unpowered X Z Output unpowered. Output pins are in high impedance state.
Outputs return to input state within 150 µs of V
DDO
power restoration.
See the pin function descriptions (Table 19 and Table 20) for details.
1
V
Ix
and V
Ox
refer to the input and output signals of a given channel (A, B, C, or D).
2
V
DDI
refers to the power supply on the input side of a given channel (A, B, C, or D).
3
V
DDO
refers to the power supply on the output side of a given channel (A, B, C, or D).