TLE4470 Datasheet, PDF (16/22 Pages) Siemens Semiconductor Group – Dual Low-Drop Voltage Regulator

TLE 4470
V I1
Band-Gap
Reference
1.35 V
TLE 4470 G
30 kΩ
Band-Gap
Reference
1.35 V
1+
_
V_Q1
RO
R₁
RADJ
GND
R₂
AES02505
Figure 5
Early Warning
The early warning function compares a voltage defined by the user to an internal
reference voltage. Therefore the voltage to be supervised has to be scaled down by an
external voltage divider in order to compare it to internal sense threshold (reference
voltage) which is typically 1.35 V. The sense out pin is set to low when the user defined
voltage falls below this threshold.
A typical example where this circuit can be used is to supervise the input voltage V_I to
give the microprocessor a prewarning of a low battery condition.
Calculation of the voltage divider can be easily done since the sense input current can
be neglected.
To minimize transient influences the use of a capacitor in parallel to R₂ is recommended.
Like the reset output pin, the sense out pin SQ is internally connected to the stand-by
output Q1 via a 30 kΩ pull-up resistor. The sense out LOW signal at pin SQ is generated
down to an input voltage V_I1 of 3 V typical.
Semiconductor Group
16
1998-11-01