Datasheet

TLE 4263
Data Sheet 11 Rev. 2.8, 2007-03-20
Reset Switching Threshold
The present default value is typ. 4.65 V. When using the TLE 4263 the reset threshold
can be set to 3.5 V <
V
Q,rt
< 4.6 V by connecting an external voltage divider to pin RADJ.
The calculation can be easily done since the reset adjust input current can be neglected.
If this feature is not needed, the pin has to be connected to GND.
V
Q,rt
= (1 + R
1
/R
2
) × V
RADJ,th
(2)
Definitions:
•
V
Q,rt
= reset threshold
•
V
RADJ,th
= comparator reference voltage, typical 1.35 V
Watchdog Timing
The frequency of the watchdog pulses has to be higher than the minimum pulse
sequence which is set by the external reset delay capacitor
C
D
. Calculation can be done
according to the formula given in Figure 6.
Figure 6 Timing of the Watchdog Function Reset
AED03099_4263
W
V
V
V
Q
D
V
V
RO
WD, L
t
WD, p
T
WI, tr
T
T =
VV (
DU
-
DWL
)
Ι
D, wd
DU
V
V
DWL
Ι
WI, tr D
C
t
t
t
t
t