SI86XX Datasheet, PDF (32/52 Pages) Silicon Laboratories – No start-up initialization required

Si86xx
3.1. Device Startup
Outputs are held low during powerup until VDD is above the UVLO threshold for time period tSTART. Following
this, the outputs follow the states of inputs.
3.2. Undervoltage Lockout
Undervoltage Lockout (UVLO) is provided to prevent erroneous operation during device startup and shutdown or
when VDD is below its specified operating circuits range. Both Side A and Side B each have their own
undervoltage lockout monitors. Each side can enter or exit UVLO independently. For example, Side A
unconditionally enters UVLO when V_DD1 falls below V_{DD1(UVLO–)} and exits UVLO when V_DD1 rises above
V_DD1(UVLO+). Side B operates the same as Side A with respect to its V_DD2 supply.
UVLO+
UVLO-
V_DD1
UVLO+
UVLO-
V_DD2
INPUT
tSTART
OUTPUT
tSD
tSTART
tSTART
tPHL tPLH
Figure 9. Device Behavior during Normal Operation
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Rev. 1.0