SI8605 Datasheet, PDF (21/40 Pages) Silicon Laboratories – BIDIRECTIONAL IC ISOLATORS WITH UNIDIRECTIONAL DIGITAL CHANNELS

Si860x
4.3. Input and Output Characteristics for Non-I²C Digital Channels
The unidirectional Si86xx inputs and outputs are standard CMOS drivers/receivers. The nominal output impedance
of an isolator driver channel is approximately 50 , ±40%, which is a combination of the value of the on-chip series
termination resistor and channel resistance of the output driver FET. When driving loads where transmission line
effects will be a factor, output pins should be appropriately terminated with controlled impedance PCB traces.
Table 14 details powered and unpowered operation of the Si86xx’s non-I²C digital channels.
Table 14. Si86xx Operation Table
V_I Input^1,4 VDDI State^1,2,3 VDDO State^1,2,3 V_O Output^1,4
Comments
H
P
L
P
P
H
Normal operation.
P
L
Upon transition of VDDI from unpowered to pow-
X⁵
UP
P
L⁶
ered, V_O returns to the same state as V_I in less
than 1 µs.
X⁵
P
Upon transition of VDDO from unpowered to pow-
UP
Undetermined _{ered, VO returns to the same state as VI 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. Powered (P) state is defined as 3.0 V < VDD < 5.5 V.
3. Unpowered (UP) state is defined as VDD = 0 V.
4. X = not applicable; H = Logic High; L = Logic Low.
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. For I²C channels, the outputs for a given side go to Hi-Z when power is lost on the opposite side.
Rev. 1.4
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