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| SI87XX Datasheet, PDF (13/36 Pages) Silicon Laboratories – 5 KV LED EMULATOR INPUT, OPEN COLLECTOR OUTPUT ISOLATORS | |||
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Si87xx
3. Technical Description
3.1. Device Behavior
Truth tables for the Si87xx are summarized in Table 10.
Table 10. Si87xx Truth Table Summary1
Input
VDD
EN2
OFF
> UVLO
H
OFF
> UVLO
L
OFF
< UVLO
H
OFF
< UVLO
L
ON
> UVLO
H
ON
> UVLO
L
ON
< UVLO
H
ON
< UVLO
L
Notes:
1. This truth table assumes VDD is powered. UVLO is typically 2.8 V.
2. Si8712 only.
3. The output voltage level is determined by the external pull-up supply.
VO3
HIGH
HIGH
HIGH
HIGH
LOW
HIGH
HIGH
HIGH
3.2. Device Startup
Output VO is held low during power-up until VDD rises above the UVLO+ threshold for a minimum time period of
tSTART. Following this, the output is high when the current flowing from anode to cathode is > IF(ON). Device startup,
normal operation, and shutdown behavior is shown in Figure 6.
UVLO
VDD
IF(ON)
IF
IHYS
tSTART
tPLH tPHL
tUVLO
tUVLO
tPLH
Voltage level
determined by
external pull-up
supply
VO
Figure 6. Si87xx Operating Behavior (IF > IF(MIN) when VF > VF(MIN))
Preliminary Rev. 0.5
13
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