5-V Low Drop Fixed Voltage Regulator TLE 4278 G Features Output voltage tolerance 2% Very low current consumption Separated reset and watchdog output Low-drop voltage Watchdog Adjustable watchdog activating threshold Adjustable reset threshold PG-DSO-14-30 Overtemperature protection P-DSO-14-3, -8, -9, -11, 14 Reverse polarity protection Short-circuit proof Suitable for use in automotive electronics Wide temperature range AEC qualified Green Product (RoHS compliant) version of TLE 4278 G Functional Description The TLE4278 is a monolithic integrated low-drop fixed output voltage regulator supplying loads up to 200 mA. The IC is available in a PG-DSO-14-30 package. It 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. The TLE 4278 can also be used in other applications where a stabilized voltage is required. An input voltage V in the range of 5.5 V V 45 V is regulated to V = 5 V with an I I Q,nom accuracy of 2%. The device operates in the wide temperature range of T = -40 to 150 C. j Two additional features are implemented in the TLE 4278 a load dependent watchdog function as well as a sophisticated reset function including power on reset, under voltage reset, adjustable reset delay time and adjustable reset switching threshold. Type Package TLE 4278 G PG-DSO-14-30 (RoHS compliant) Data Sheet 1 Rev. 1.4, 2007-02-19 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 when the output voltage of the regulator has surpassed the reset threshold. The rd delay time is set by the external delay capacitor. An under voltage reset circuit supervises the output voltage. In case V falls below the reset threshold the reset output Q is set to LOW after a short reset reaction time t . The reset LOW signal is generated rr down to an output voltage V of 1 V. In addition the reset switching threshold can be Q 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