20 Rev. 1.3
Si8660/61/62/63
3. Device Operation
Device behavior during start-up, normal operation, and shutdown is shown in Figure 7, where UVLO+ and UVLO-
are the positive-going and negative-going thresholds respectively. Refer to Table 12 to determine outputs when
power supply (VDD) is not present.
Table 12. Si866x Logic Operation
V
I
Input
1,2
VDDI
State
1,3,4
VDDO
State
1,3,4
V
O
Output
1,2
Comments
HP P H
Normal operation.
LP P L
X
5
UP P
L
6
H
6
Upon transition of VDDI from unpowered to powered, V
O
returns to the same state as V
I
in less than 1 µs.
X
5
P UP Undetermined
Upon transition of VDDO from unpowered to powered, V
O
returns to the same state as V
I
within 1 µs.
Notes:
1. VDDI and VDDO are the input and output power supplies. V
I
and V
O
are the respective input and output terminals.
2. X = not applicable; H = Logic High; L = Logic Low; Hi-Z = High Impedance.
3. “Powered” state (P) is defined as 2.5 V < VDD < 5.5 V.
4. “Unpowered” state (UP) is defined as VDD = 0 V.
5. Note that an I/O can power the die for a given side through an internal diode if its source has adequate current.
6. See "5. Ordering Guide" on page 26 for details. This is the selectable fail-safe operating mode (ordering option). Some
devices have default output state = H, and some have default output state = L, depending on the ordering part number
(OPN). For default high devices, the data channels have pull-ups on inputs/outputs. For default low devices, the data
channels have pull-downs on inputs/outputs.
