LT3437EDD#PBF

LT3437 High Voltage 500mA, 200kHz Step-Down Switching Regulator with 100µA Quiescent Current DESCRIPTIO U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 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. 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 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). U APPLICATIO S ■ ■ ■ ■ ■ ■ High Voltage Power Conversion 14V and 42V Automotive Systems Industrial Power Systems Distributed Power Systems Battery-Powered Systems Powered Ethernet 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. , 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. U TYPICAL APPLICATIO 14V to 3.3V Step-Down Converter with 100µA No Load Quiescent Current 2.2µF 100V CER VIN BOOST 0.1µF SHDN SW LT3437 VC 1500pF 200 330pF 0.1µF 100µH BAS21 VOUT 3.3V 400mA 10MQ100N CSS VBIAS 27pF 25k SYNC 165k FB GND *FOR INPUT VOLTAGES ABOVE 60V RESTRICTIONS APPLY 100k 100µF 6.3V TANT 180 160 SUPPLY CURRENT (µA) VIN 4.5V TO 80V* Input Voltage Transient Response Supply Current vs Input Voltage VIN 20V/DIV 140 120 VIN 0V 100 80 VOUT 20mV/DIV AC COUPLED 60 40 IOUT 250mA 20 3437 TA01 LOAD DUMP 3437 TA03 50ms/DIV COLD CRANK 0 0 10 20 30 40 50 60 INPUT VOLTAGE (V) 70 80 3437 TA02 3437fc 1 LT3437 U W W W ABSOLUTE AXI U RATI GS (Note 1) VIN, SHDN, BIAS, SW Operating ............................. 60V VIN, SHDN 100ms Transient,