TLE4278G_07 Datasheet, PDF (2/20 Pages) Infineon Technologies AG – 5-V Low Drop Fixed Voltage Regulator Output voltage tolerance ≤ ±2%

TLE 4278 G
The watchdog function monitors the microcontroller, including time base failures. In case
of a missing rising edge within a certain pulse repetition time the watchdog output is set
to LOW. Programming of the max. repetition time can be done easily by an external reset
delay capacitor. To prevent a reset in case of missing pulses, the watchdog output WO
is separate from the reset output RO for the TLE 4278. The watchdog output can be
used as an interrupt signal for the microcontroller. In any case it is possible to connect
pin WO and pin RO externally.
When the controller is set to sleep mode or low power mode its current consumption
drops and no watchdog pulses are created. In order to avoid unnecessary wake-up
signals due to missing pulses at pin WI the watchdog feature can be disabled as a
function of the load current. The switch off threshold is set by an external resistor to pin
WADJ. The watchdog function can also be used as a timer, which periodically wakes up
the controller. Therefore the pin WADJ has to be connected to the output Q.
The power on reset feature is necessary for a defined start of the microprocessor when
switching on the application. The reset signal at pin RO goes high after a certain delay
timed t_rd when the output voltage of the regulator has surpassed the reset threshold. The
delay time is set by the external delay capacitor. An under voltage reset circuit
supervises the output voltage. In case V_Q falls below the reset threshold the reset output
is set to LOW after a short reset reaction time t_rr. The reset LOW signal is generated
down to an output voltage V_Q of 1 V. In addition the reset switching threshold can be
adjusted by an external voltage divider. This feature is useful with microprocessors
which guarantee a safe operation down to voltages below the internally set reset
threshold of 4.65 V typical.
Data Sheet
2
Rev. 1.4, 2007-02-19