Rev. 1.1, 2007-10-17
The TLE 4299 is a PNP based very low drop linear voltage regulator. It regulates the
output voltage to
Q = 3.3 V for an input voltage range of 4.4 V ≤ VI ≤ 45 V. The control
circuit protects the device against potential damages caused by overcurrent and
The internal control circuit achieves a 3.3 V output voltage with a tolerance of
The device includes a power on reset and an under voltage reset function with adjustable
reset delay time and adjustable reset switching threshold as well as a sense control/early
warning function. The device includes an inhibit function to disable it when the ECU is
not used for example while the motor is off.
The reset logic compares the output voltage
Q to an internal threshold. If the output
voltage drops below this level, the external reset delay capacitor
D is discharged. When
D is lower than VST, the reset output RO is switched Low. If the output voltage drop is
very short, the
ST level is not reached and no reset-signal is asserted. This feature
avoids resets at short negative spikes at the output voltage e.g. caused by load changes.
As soon as the output voltage is more positive than the reset threshold, the delay
capacitor is charged with constant current. When the voltage reaches
DT the reset
output RO is set High again.
The reset delay time and the reset reaction time are defined by the external capacitor
D. The reset function is active down to VI = 1 V.
In addition to the normal reset function, the device gives an early warning. When the SI
voltage drops below
SI,low, the devices asserts the SI output Low to indicate the logic
µ-processor that this voltage has dropped. The sense function uses a hysteresis:
When the SI-voltage reaches the
SI,high level, SO is set high again. This feature can be
used as early warning function to notice the
µ-controller about a battery voltage drop and
a possible reset in a short time. Of course also any other voltage can be observed by this
The user defines the threshold by the resistor-values
SI1 and RSI2.
For the exact timing and calculation of the reset and sense timing and thresholds, please
refer to the application section.