L4946
low when V04 drops 0.15 below it’s typical value.
A reset will occur between a minimum of 4.5V
and a maximum of 5V on V04. When the V04
drops between 4.5 and 5V the RESET output
goes low. It is very important that the RESET out-
FUNCTIONAL DESCRIPTION
The L4946 includes a monitoring circuit to warn
the microprocessor if a low voltage or no voltage
condition is occurring. Between 7V and 8V on the
STCAP pin, the LVW output will go low. This tells
the microprocessor to stop executing code and
save vital information. The reset output will go low
when V04 drops 0.15V below it’s typical reading.
A reset will occur between a minimum of 4.5 and
a maximum of 5V on V04. The reset output will go
04
put doesn’t go above 0.75V until the V output
has gone back above 4.75V (typical). The micro-
processor looks for a rising edge. So, any spike
will tell the microprocessor to start operating.
Once the STCAP line passes 7.5V (typical), the
LVW output will also return to high state.
TIMING DIAGRAM
7.5
7.5
5.0
100µs
150µs
5.0
150µs
100µs
Graphs of the Output Curves for VO1,2,3 and 4
6/9
STMICROELECTRONICS [ ST ]
