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

A reset will occur between a minimum of 4.5 and

A reset will occur between a minimum of 4.5V

drops between 4.5 and 5V

the RESET output

goes low. It is very important that the RESET out-

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

5.0

5.0

7.5

7.5

150

µs

100

µs

150

µs100µs

L4946

6/9