Datasheet

Data Sheet 12 Rev. 1.4, 2007-02-19
TLE 4278 G
Reset Switching Threshold
The present default value is 4.65 V. When using the TLE 4278 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
= V
ref
× (1 + R
1
/R
2
)(3)
Definitions:
•
V
Q,rt
= Reset threshold
•
V
ref
= comparator reference voltage, typical 1.35 V
(Reset adjust input current ≈ 50 nA)
Figure 6
The reset output pin is internally connected to the 5 V output Q via a 30 kΩ pull-up
resistor. Down to an output voltage
V
Q
of typical 1 V the reset LOW signal at pin RO is
generated.
For the timing of the reset feature please refer to Figure 5.
AES03071
Band-Gap-
Reference
RO
RADJ
Ι
GND
Q
Reference
Band-Gap-
>
1
+
-
1.35 V 1.35 V
30 kΩ
R
1
2
R
TLE 4278 G
13 9
14
7
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