TLE4278G Datasheet, PDF (12/18 Pages) Siemens Semiconductor Group – 5-V Low-Drop Fixed Voltage Regulator

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_RTH < 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 unused, the pin can be left open or even better connected to GND.
Definitions:
R₁ = R₂ × (V_RTH – V_ref)/V_ref
V_RT = Reset threshold
V_ref = comparator reference voltage, typical 1.35 V
(Reset adjust input current ≈ 50 nA)
TLE 4278 G
V_Ι
V_Q
30 kΩ
Band-Gap-
Reference
1.35 V
Band-Gap-
Reference
1.35 V
>1
RO
R₁
RADJ
GND
R₂
AES02553
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 in
generated.
For the timing of the reset feature please refer to the data sheet, figure 5.
Semiconductor Group
12
1998-11-01