LT3972 33V, 3.5A, 2.4MHz Step-Down Switching Regulator with 75A Quiescent Current FEATURES DESCRIPTION Wide Input Range: The LT 3972 is an adjustable frequency (200kHz to 2.4MHz) Operation from 3.6V to 33V monolithic buck switching regulator that accepts input Overvoltage Lockout Protects Circuits voltages up to 33V (62V maximum). A high ef ciency Through 62V Transients 95m switch is included on the die along with a boost 3.5A Maximum Output Current Schottky diode and the necessary oscillator, control and Low Ripple (<15mV ) Burst Mode Operation: logic circuitry. Current mode topology is used for fast P-P I = 75A at 12V to 3.3V transient response and good loop stability. Low ripple Q IN OUT Adjustable Switching Frequency: 200kHz to 2.4MHz Burst Mode operation maintains high ef ciency at low Low Shutdown Current: I < 1A output currents while keeping output ripple below 15mV Q Integrated Boost Diode in a typical application. In addition, the LT3972 can fur- Synchronizable Between 250kHz to 2MHz ther enhance low output current ef ciency by drawing Power Good Flag bias current from the output when V is above 3V. OUT Saturating Switch Design: 95m On-Resistance Shutdown reduces input supply current to less than 1A Output Voltage: 0.79V to 30V while a resistor and capacitor on the RUN/SS pin provide a Thermal Protection controlled output voltage ramp (soft-start). A power good Soft-Start Capability ag signals when V reaches 91% of the programmed OUT Small 10-Pin Thermally Enhanced MSOP and output voltage. The LT3972 is available in 10-pin MSOP (3mm 3mm) DFN Packages and 3mm 3mm DFN packages with exposed pads for low thermal resistance. APPLICATIONS L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Automotive Battery Regulation Distributed Supply Regulation Industrial Supplies Wall Transformer Regulation TYPICAL APPLICATION 5V Step-Down Converter Ef ciency V OUT 100 V IN 5V 6.3V TO 33V 3.5A TRANSIENT V = 12V IN V BD TO 62V IN 90 OFF ON RUN/SS BOOST V = 30V IN 80 V = 24V IN 0.47F 4.7H 15k V SW LT3972 C 10F 70 RT 680pF PG 60 V = 5V 536k OUT 63.4k SYNC L = 4.7H FB GND f = 600kHz 50 100k 47F 0 0.5 1 1.5 2 2.5 3 3.5 OUTPUT CURRENT (A) 3972 TA01 3972 TA01a 3972fa 1 EFFICIENCY (%)LT3972 ABSOLUTE MAXIMUM RATINGS (Note 1) Operating Junction Temperature Range (Note 2) V , RUN/SS Voltage (Note 5) ...................................62V IN LT3972E .............................................40C to 125C BOOST Pin Voltage ...................................................56V LT3972I ..............................................40C to 125C BOOST Pin Above SW Pin .........................................30V LT3972H ............................................40C to 150C FB, RT, V Voltage .......................................................5V C Storage Temperature Range ...................65C to 150C PG, BD, SYNC Voltage ..............................................30V Lead Temperature (Soldering, 10 sec) (MSE Only) ....................................................... 300C PIN CONFIGURATION TOP VIEW TOP VIEW BD 1 10 RT BD 1 10 RT BOOST 2 9 V C BOOST 2 9 V C 11 SW 3 8 FB 11 SW 3 8 FB V 4 7 PG IN 4 7 V PG IN RUN/SS 5 6 SYNC RUN/SS 5 6 SYNC MSE PACKAGE 10-LEAD PLASTIC MSOP DD PACKAGE = 45C/W, = 10C/W JA JC 10-LEAD (3mm 3mm) PLASTIC DFNs EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB = 45C/W, = 10C/W JA JC EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3972EDD PBF LT3972EDD TRPBF LDXR 10-Lead (3mm 3mm) Plastic DFN 40C to 125C LT3972IDD PBF LT3972IDD TRPBF LDXR 10-Lead (3mm 3mm) Plastic DFN 40C to 125C LT3972EMSE PBF LT3972EMSE TRPBF LTDXS 10-Lead Plastic MSOP 40C to 125C LT3972IMSE PBF LT3972IMSE TRPBF LTDXS 10-Lead Plastic MSOP 40C to 125C LT3972HMSE PBF LT3972HMSE TRPBF LTDXS 10-Lead Plastic MSOP 40C to 150C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: