LP2951-02BN

LP2951 100 mA Low-Dropout Voltage Regulator Features General Description • • • • • • • • • • • The LP2951 is micropower voltage regulators with very low dropout voltage (typically 40 mV at light loads and 380 mV at 100 mA), and very low quiescent current (75 μA typical). The quiescent current of the LP2951 increases only slightly in dropout, thus prolonging battery life. This feature, among others, makes the LP2951 ideally suited for use in battery-powered systems. High Accuracy 5V, Guaranteed 100 mA Output Extremely Low Quiescent Current Low-Dropout Voltage Extremely Tight Load and Line Regulation Very Low Temperature Coefficient Use as Regulator or Reference Needs Only 1 μF for Stability Current and Thermal Limiting Error Flag Warns of Output Dropout Logic-Controlled Electronic Shutdown Output Programmable from 1.24V to 29V Applications • Automotive Electronics • Voltage Reference • Avionics Available system functions, such as programmable output voltage and logic-controlled shutdown, are available as well. Additional features available with the LP2951 also include an error flag output that warns of a low output voltage, which is often due to failing batteries on the input. This may also be used as a power-on reset. A logic-compatible shutdown input is also available which enables the regulator to be switched on and off. This part may also be pin-strapped for a 5V output, or programmed from 1.24V to 29V with the use of two external resistors. The LP2951 is available as either a -02 or -03 version. The -02 and -03 versions are guaranteed for junction temperatures from -40°C to +125°C; the -02 version has a tighter output and reference voltage specification range over temperature. The LP2951 have a tight initial tolerance (0.5% typical), a very low output voltage temperature coefficient which allows use as a low-power voltage reference, and extremely good load and line regulation (0.05% typical). This greatly reduces the error in the overall circuit, and is the result of careful design techniques and process control. Package Types LP2951 DIP & SOIC Top View 1 8 SENSE 2 7 SHUTDOWN 3 6 4 5 OUTPUT GROUND INPUT FEEDBACK 5V TAP ERROR * See MIC2950 for a part with: 1) higher output (150 mA), 2) transient protection (60V), and 3) reverse input protection to –20V.  2017 - 2022 Microchip Technology Inc. and its subsidiaries DS20005736B-page 1 LP2951 Functional Block Diagram 5V 150 mA MAX. UNREGULATED DC 7 + 8 FEEDBACK INPUT 1 OUTPUT 2 SENSE + 3 FROM CMOS OR TTL – SHUTDOWN 182 kΩ 60 mV 1.23 V REF. – + 5V TAP 60 kΩ + + 6 ERROR AMPLIFIER + 5 330 kΩ 1.5 μF TO CMOS OR TTL ERROR ERROR DETECTION COMPARATOR 4 GROUND Typical Application Diagrams +V IN +VIN 8 +VIN ERROR OUTPUT 5 VOUT ERROR 1 *VOUT ≈ VIN LP2951 FB 4 7 5 470 kΩ 8 +V IN ERROR WIDE INPUT VOLTAGE RANGE CURRENT LIMITER +V OUT V OUT 1 LP2951 MIC2951 SHUTDOWN 3 SD INPUT OFF FB GND ON 7 4 *MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40 mV TO 400 mV, DEPENDING ON LOAD CURRENT. CURRENT LIMIT IS TYPICALLY 160 mA. IL 47kΩ ERROR OUTPUT SHUTDOWN 3 SO INPUT GND +V = 2 C-MOS GATE *SLEEP INPUT 200kΩ + 2N3906 1% 100kΩ 100pF 3.3μF 1% 100kΩ *HIGH INPUT LOWERS VOUT TO 2.5V 5V REGULATOR WITH 2.5V SLEEP FUNCTION 30V I L= LOAD 1.23 R 8 VIN VOUT 1 LP2951 SHUTDOWN 3 SD INPUT GND FB 4 0.1μF 7 R 1% 1μF LOW DRIFT CURRENT SOURCE DS20005736B-page 2  2017 - 2022 Microchip Technology Inc. and its subsidiaries LP2951 Typical Application Diagrams +V IN D1 +V IN 2 SENSE 8 +V IN VOUT D2 1 MEMORY V+ 8 470k 20 LP2951 #1 5 ERROR 1μF 3.6V NICAD +V IN 5 470k GND 4 Q1 RESET 2 SENSE SD VOUT LP2951 #2 5 ERROR 330kΩ MAIN OUTPUT + 7 + FB SD 1μF R2 GND RESET 8 +V IN 1 3 3 EARLY WARNING D3 D4 2.7MΩ R1 LP2951 27kΩ VOUT VOUT 1 ERROR 4 μP VDO LATCH-OFF WHEN ERROR FLAG OCCURS 1μf GND 4 • EARLY WARNING FLAG ON LOW INPUT VOLTAGE • MAIN OUTPUT LATCHES OFF AT LOWER INPUT VOLTAGES • BATTERY BACKUP ON AUXILIARY OUTPUT OPERATION: REG. #1’S VOUT IS PROGRAMMED ONE DIODE DROP ABOVE 5V. ITS ERROR FLAG BECOMES ACTIVE WHEN VIN ≤ 5.7V. WHEN V IN DROPS BELOW 5.3V, THE ERROR FLAG OF REG. #2 BECOMES ACTIVE AND VIA Q1 LATCHES THE MAIN OUTPUT OFF. WHEN VIN AGAIN EXCEEDS 5.7V REG. #1 IS BACK IN REGULATION AND THE EARLY WARNING SIGNAL RISES, UNLATCHING REG. #2 VIA D3. REGULATOR WITH EARLY WARNING AND AUXILIARY OUTPUT 4 +5V 4.7mA 20mA 8 +VIN 39kΩ 8 1 V IN 1N 4001 V OUT VOUT 1 ERROR RESET LP2951 – 3 C4 + 4 7 2 FB GND 4 5 1 LP2951 0.1μF OUTPUT* 5 2 SENSE 360 39kΩ * HIGH FOR IL < 3.5mA FB SD GND 4 +VOUT = 5V + 1μF 7 TAP 6 1N457 + MIN. VOLTAGE 4V OPEN CIRCUIT DETECTOR FOR 4 mA TO 20 mA CURRENT LOOP 6V 1% LEADACID BATTERY 1% 100 kΩ – 100kΩ C1 + 1 kΩ –