TLE4299GV33 Datasheet, PDF (16/24 Pages) Infineon Technologies AG – Low-Drop Fixed Voltage Regulator

TLE 4299
Early Warning
The early warning function compares a voltage defined by the user to an internal reference
voltage. Therefore the supervised voltage has to be scaled down by an external voltage divider in
order to compare it to the internal sense threshold of typical 1.36 V. The sense output pin is set
low, when the voltage at SI falls below this threshold.
A typical example where the circuit can be used is to supervise the input voltage V_I to give the
microcontroller a prewarning of low battery condition.
Calculation to the voltage divider can be easily done since the sense input current can be
neglected.
Sense
Input
Voltage
V_{SI, High}
V_{SI, Low}
Sense
Output
High
t _{PD SO LH}
t
t _{PD SO HL}
Low
t
Figure 9
Sense Timing Diagram
V_thHL = (R_SI1 + R_SI2)/R_SI2 × V_{SI low}
[4]
V_thLH = (R_SI1 + R_SI2)/R_SI2 × V_{SI high}
[5]
The sense in comparator uses a hysteresis of typical 90 mV. This hysteresis of the supervised
threshold is multiplied by the resistor dividers amplification (R_SI1 + R_SI2)/R_SI1.
The sense in comparator can also be used for receiving data with a threshold of typical 1.36 V and
a hysteresis of 90 mV. Of course also the data signal can be scaled down with a resistive divider
as shown above. With a typical delay time of 2.5 µs for positive transitions and 2.4 µs for negative
transitions receiving data of up to 100 kBaud are possible. The sense output is an open collector
output.
Datasheet Rev. 1.0
16
2005-01-27