ILE4278

The ILE 4278 is a monolithic integrated low-drop fixed-voltage regulator which can supply loads up to 200 mA. ILE4278 is available in the 14-SOP-225 package. ILE4278 is designed to supply microprocessor systems under the severe conditions of automotive applications and therefore equipped with additional protection functions against over load, short circuit and overtemperature. Of course the ILE 4278 can also be used in other applications where a stabilized voltage is required.

An input voltage V_I ILE4278 in the range of 6V V_I 28V is regulated to V_Q,nom = 5 V with an accuracy of ± 2%.

An input voltage V_I ILE4278 in the range of 28V V_I 45 V is regulated to V_Q,nom = 5 V with aaccuracy of± 4%.

ILE4278 operates in the wide temperature range of T_j = 40 to 125 .

Two additional features are implemented in the ILE 4278 a load dependent watchdog function of ILE4278 as well as a sophisticated reset function including power on reset, under voltage reset, adjustable reset delay time and adjustable reset switching threshold.

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 of ILE4278 is set to LOW. Programming of the max. repetition time of ILE4278 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 ILE 4278. The watchdog output of ILE4278 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 ILE4278 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 of ILE4278  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 ILE4278 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 of ILE4278 is set by the external delay capacitor. An under voltage reset circuit of ILE4278 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. ILE4278 feature is useful with microprocessors which guarantee a safe operation down to voltages below the internally set reset threshold of 4.65 V typical.