POWER LOSS (W) LT8640/LT8640-1 42V, 5A Synchronous Step-Down Silent Switcher with 2.5A Quiescent Current Fea T Descrip T n Silent Switcher Architecture The LT 8640/LT8640-1 step-down regulator features Silent n Ultralow EMI/EMC Emissions Switcher architecture designed to minimize EMI/EMC emis- n Spread Spectrum Frequency Modulation sions while delivering high efficiency at frequencies up to n High Efficiency at High Frequency 3MHz. Assembled in a 3mm 4mm QFN, the monolithic n Up to 96% Efficiency at 1MHz construction with integrated power switches and inclusion n Up to 95% Efficiency at 2MHz of all necessary circuitry yields a solution with a minimal n Wide Input Voltage Range: 3.4V to 42V PCB footprint. An ultralow 2.5A quiescent currentwith n 5A Maximum Continuous Output, 7A Peak the output in full regulationenables applications requiring Transient Output highest efficiency at very small load currents. Transient n Ultralow Quiescent Current Burst Mode Operation response remains excellent and output voltage ripple is n 2.5A I Regulating 12V to 3.3V below 10mV at any load, from zero to full current. Q IN OUT P-P n Output Ripple < 10mV P-P The LT8640/LT8640-1 allows high V to low V conversion at IN OUT n Fast Minimum Switch-On Time: 35ns high frequency with a fast minimum top switch on-time of 35ns. n Low Dropout Under All Conditions: 100mV at 1A Operation is safe in overload even with a saturated inductor. n Forced Continuous Mode (LT8640-1 Only) n Essential features are included and easy to use: An open- Safely Tolerates Inductor Saturation in Overload n drain PG pin signals when the output is in regulation. The Adjustable and Synchronizable: 200kHz to 3MHz n SYNC/MODE pin selects between Burst Mode operation, Peak Current Mode Operation n spread spectrum mode, synchronization to an external Output Soft-Start and Tracking n clock, and either pulse-skipping (LT8640) or forced Small 18-Lead 3mm 4mm QFN continuous mode (LT8640-1). Soft-start and tracking functionality is accessed via the TR/SS pin. An accurate a T enable threshold can be set using the EN/UV pin and a n Automotive and Industrial Supplies resistor at the RT pin programs switch frequency. n General Purpose Step-Down L, LT, LTC, LTM, Linear Technology, the Linear logo, Silent Switcher and Burst Mode are n GSM Power Supplies registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. 12V to 5V Efciency Typical a T IN OUT 3.00 100 5V 5A Step-Down Converter 95 2.63 V IN 5.5V TO 42V 90 2.25 4.7F EFFICIENCY EN/UV V V IN1 IN2 1F 1F 85 1.88 GND1 GND2 LT8640/ 80 1.50 PG LT8640-1 BST 3.3H 0.1F V OUT 10nF 75 1.13 5V SYNC/MODE SW POWER LOSS 5A TR/SS BIAS 70 0.75 1F 4.7pF 1M 1MHz, L = 3.3H 65 0.38 47F 2MHz, L = 2.2H INTV FB CC 41.2k 3MHz, L = 1H 243k 60 0 RT GND 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 LOAD CURRENT (A) f = 1MHz SW 8640 TA01a 8640 TA01b 8640fa 1 For more information www.linear.com/LT8640 EFFICIENCY (%) ion pplica ions pplica ion uresLT8640/LT8640-1 a Te Maxi Mu M r a T p in c F T (Note 1) TOP VIEW V , EN/UV, PG ..........................................................42V IN BIAS ..........................................................................25V FB, TR/SS ................................................................4V SYNC Voltage ...........................................................6V 20 19 18 17 Operating Junction Temperature Range (Note 2) 1 16 BIAS TR/SS LT8640E/LT8640-1E .......................... 40C to 125C INTV 2 15 RT CC LT8640I/LT8640-1I ............................ 40C to 125C BST 3 EN/UV 14 LT8640H ............................................ 40C to 150C 22 V 4 VIN2 13 IN1 SW Storage Temperature Range ......................65 to 150C 21 GND1 6 SW 11 GND2 7 8 9 10 UDC PACKAGE 18-LEAD (3mm 4mm) PLASTIC QFN = 40C/W, = 12C/W JA JC(PAD) EXPOSED PAD (PINS 21, 22) ARE SW, SHOULD BE SOLDERED TO PCB NOTE: PINS 5 AND 12 ARE REMOVED. CONFIGURATION DOES NOT MATCH JEDEC 20-LEAD PACKAGE OUTLINE o r Der i n F Ma T LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT8640EUDC PBF LT8640EUDC TRPBF LGNJ 18-Lead (3mm 4mm) Plastic QFN 40C to 125C LT8640IUDC PBF LT8640IUDC TRPBF LGNJ 40C to 125C 18-Lead (3mm 4mm) Plastic QFN LT8640HUDC PBF LT8640HUDC TRPBF LGNJ 18-Lead (3mm 4mm) Plastic QFN 40C to 150C LT8640EUDC-1 PBF LT8640EUDC-1 TRPBF LGVT 18-Lead (3mm 4mm) Plastic QFN 40C to 125C LT8640IUDC-1 PBF LT8640IUDC-1 TRPBF LGVT 18-Lead (3mm 4mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: