Data Sheet 2 Rev. 1.1, 2004-01-01
TLE 4299
Circuit Description
The TLE 4299 is a PNP based very low drop linear voltage regular. It regulates the
output voltage to
V
Q
= 5 V for an input voltage range of 5.5 V ≤ V
I
≤ 45 V. The control
circuit protects the device against potential caused by damages overcurrent and
overtemperature.
The internal control circuit achieves a 5 V output voltage with a tolerance of
±2%.
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
V
Q
to an internal threshold. If the output
voltage drops below this level, the external reset delay capacitor
C
D
is discharged. When
V
D
is lower than V
LD
, the reset output RO is switched Low. If the output voltage drop is
very short, the
V
LD
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
V
UD
the reset
output RO is set High again.
The reset threshold is either the internal defined
V
RT
voltage (typical 4.6 V) or can be
lowered by a voltage level at the RADJ input down to 3.5 V. The reset delay time and the
reset reaction time are defined by the external capacitor
C
D
. The reset function is active
down to
V
I
= 1 V.
In addition to the normal reset function, the device gives an early warning. When the SI
voltage drops below
V
SI,low
, the devices asserts the SI output Low to indicate the logic
and the
µ-processor that this voltage has dropped. The sense function uses a hysteresis:
When the SI-voltage reaches the
V
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 cause also any other voltage can be observed by this
feature.
The user defines the threshold by the resistor-values
R
SI1
and R
SI2
.
For the exact timing and calculation of the reset and sense timing and thresholds, please
refer to the application section.
