ILE4278_13 Datasheet, PDF (2/18 Pages) IK Semicon Co., Ltd – 5-V Low-Drop Fixed Voltage Regulator

ILE4278
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 trd 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 VQ falls below the reset threshold the reset
output is set to LOW after a short reset reaction time trr. The reset LOW signal is
generated down to an output voltage VQ 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.
June, 2013, Rev. 02