LT8603 42V, Low IQ, Quad Output Triple Monolithic Buck Converter and Boost Controller FEATURESDESCRIPTION n Flexible Power Supply System Capable of Four The LT®8603 is a highly flexible, quad output regulator Regulated Outputs with VBATT << VOUT combining two high input voltage capable monolithic n Two High Voltage Synchronous Buck Regulators step-down switching regulators, one low input voltage n 3V to 42V Input Voltage Range capable monolithic step-down regulator, and a boost n Output Currents Up to 2.5A and 1.5A controller to satisfy a wide range of applications while n One Low Voltage Synchronous Buck Regulator occupying minimal board space. n 2.6V to 5.5V Input Voltage Range With the boost controller configured to supply the chip n Output Currents Up to 1.8A VIN supply, the LT8603 produces three precisely regulated n One Boost Controller Allows Buck Converters to outputs even when the boost input voltage falls signifi- Regulate with VBATT << VOUT cantly below the regulated output voltages, such as dur- n Selectable Burst Mode® Operation Allows Low ing an automotive cold crank scenario. Alternatively, with 28µA IQ with High Voltage Channels Active the boost controller driven from one of the step-down n Programmable Power-On Reset regulator outputs or configured as a SEPIC, the LT8603 n Individual Channel Power Good Indicators provides four precisely regulated outputs over a wide n Step-Down Switching Frequency: 250kHz to 2.2MHz input voltage range. n Available in 40-Lead QFN (6mm × 6mm) Package n AEC-Q100 Qualified for Automotive Applications The LT8603 provides robust regulation by including a cycle-by-cycle current limit for all step-down regulators, thermal shutdown, and a boost controller that can tolerate APPLICATIONS reverse battery connections and negative transient input n Automotive Stop-Start and Cold Crank Ride Through voltages down to –42V. n Last-Gasp CPU Power Hold-Up All registered trademarks and trademarks are the property of their respective owners. n Industrial Controls and Power Supplies TYPICAL APPLICATIONCold Crank Tolerant Automotive Triple Output SupplyLT8603 Response to a Cold Crank VBATT OUT4 Automotive Input Waveform 2V TO 42V 8V FOR (BOOST 2V < VBATT < 8.5V START-UP ABOVE 4.3V) EN/UVLO VIN PVIN1 PVIN2 ISP4 ISN4 V INTV GATE4 BATT CC4 VOUT4 INTVCC FB4 FSEL4A FSEL4B BST1 RT SYNC SW1 OUT1 5V, 1.5A VOLTAGE CPOR 2V/DIV 2 LT8603 FB1 V TRKSS1-2 OUT1 BST2 VOUT2 PVIN3 SW2 OUT2 3.3V, RUN3 2.5A – I V OUT2 BIAS PVIN3 FB2 OUT3 4 0V PG1-4 PG1-4 SW3 OUT3 POREN POREN 1.2V, 1.8A 8603 TA01b RESET RST TIME (10ms/DIV) GND FB3 8603 TA01a Rev. B Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information System Architecture Boost Controller Buck Regulators General Functions PCB Layout Thermal Considerations Typical Applications Package Description Revision History Related Parts