LT3437IFE

LT3437 High Voltage 500mA, 200kHz Step-Down Switching Regulator with 100µA Quiescent Current DESCRIPTIO The LT®3437 is a 200kHz monolithic buck switching regulator that accepts input voltages up to 80V. A high efficiency 500mA, 0.8Ω switch is included on the die along with all the necessary oscillator, control and logic circuitry. Current mode topology is used for fast transient response and good loop stability. Innovative design techniques along with a new high voltage process achieve high efficiency over a wide input range. Efficiency is maintained over a wide output current range by employing Burst Mode operation at low currents, utilizing the output to bias the internal circuitry, and by using a supply boost capacitor to fully saturate the power switch. Burst Mode operation can be defeated by a logic high signal on the SYNC pin which results in lower light load ripple at the expense of light load efficiency. Patented circuitry maintains peak switch current over the full duty cycle range.* Shutdown reduces input supply current to less than 1µA. External synchronization can be implemented by driving the SYNC pin with logic-level inputs. A single capacitor from the CSS pin to the output provides a controlled output voltage ramp (soft-start). The LT3437 is available in a low profile (0.75mm) 3mm × 3mm 10-pin DFN package or a 16-Pin TSSOP Package, both with exposed pad leadframes for low thermal resistance. FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Wide Input Range: 3.3V to 60V Load Dump (Input Transient) Protection to 80V 500mA Peak Switch Current Burst Mode® Operation: 100µA Quiescent Current** Low Shutdown Current: IQ < 1µA Defeatable Burst Mode Operation 200kHz Switching Frequency Saturating Switch Design: 0.8Ω On-Resistance Peak Switch Current Maintained Over Full Duty Cycle Range* 1.25V Feedback Reference Voltage Easily Synchronizable Soft-Start Capability Small 10-Pin Thermally Enhanced DFN Package APPLICATIO S ■ ■ ■ ■ ■ ■ High Voltage Power Conversion 14V and 42V Automotive Systems Industrial Power Systems Distributed Power Systems Battery-Powered Systems Powered Ethernet , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents, including 6498466. **See Burst Mode Operation section for conditions. TYPICAL APPLICATIO 14V to 3.3V Step-Down Converter with 100µA No Load Quiescent Current SUPPLY CURRENT (µA) VIN 4.5V TO 80V* Supply Current vs Input Voltage 200 VOUT 3.3V 400mA 180 160 140 120 VIN 20V/DIV 2.2µF 100V CER VIN SHDN BOOST SW CSS 0.1µF 0.1µF 100µH BAS21 10MQ100N LT3437 VC 100 80 60 1500pF 25k 330pF VBIAS 27pF 165k SYNC GND FB 100k 100µF 6.3V TANT 40 20 *FOR INPUT VOLTAGES ABOVE 60V RESTRICTIONS APPLY 3437 TA01 0 0 10 20 30 40 50 60 INPUT VOLTAGE (V) 70 80 3437 TA02 U U U Input Voltage Transient Response VIN 0V VOUT 20mV/DIV AC COUPLED IOUT 250mA LOAD DUMP 50ms/DIV COLD CRANK 3437 TA03 3437fc 1 LT3437 ABSOLUTE (Note 1) AXI U RATI GS Operating Junction Temperature Range LT3437EDD (Note 2) ....................... – 40°C to 125°C LT3437IDD (Note 2) ........................ – 40°C to 125°C LT3437EFE (Note 2) ........................ – 40°C to 125°C LT3437IFE (Note 2) ......................... – 40°C to 125°C LT3437HFE (Note 2) .......................... –40°C to 140°C Storage Temperature Range ................. – 65°C to 125°C DD Package ....................................... –65°C to 125°C FE Package ........................................ –65°C to 150°C VIN, SHDN, BIAS, SW Operating ............................. 60V VIN, SHDN 100ms Transient,