Data Sheet

2

Rev. 1.2, 2008-10-28

TLE 4473 GV55-2

The device features a reset with adjustable power on delay for each of the outputs. In

addition the output for the microcontroller supply comes up with a watchdog in order to

supervise a connected microcontroller

Reset and Watchdog Behavior

The reset output RO2 is in high-state if the voltage on the delay capacitor

C

or equal

V

voltages greater than the reset threshold V

(‘reset condition’) a fast discharge of the delay capacitor

C

gets lower than

V

capacitor charge is the reset delay time. For the power-on case the charging process of

C

(1)

for the power-on reset delay time.

When the voltage on the delay capacitor has reached

V

watchdog circuit is enabled and discharges

C

If there is no rising edge observed at the watchdog input,

C

V

current

I

If the watchdog pulse (rising edge at watchdog input WI) occurs during the discharge

period

C

the periodical cycle starts again.

watchdog pulses corresponds to the minimum watchdog trigger time

T

capacitances on pin D2 result in longer watchdog trigger times:

(2)

If the output voltage Q1 decreases below

V

is discharged by the reset generator of the main output. If the voltage on this capacitor

drops below

V

above the reset threshold,

C

power-on-reset time the voltage on the capacitor reaches

V

be set high again. The value of the power-on-reset time can be set within a wide range

depending of the capacitance of

C

Q1.

,

×

-----------------------------

=

max

0.34 ms/nF

×

=