POWER LOSS (W) LT8640S/LT8643S 42V, 6A Synchronous Step-Down Silent Switcher 2 with 2.5A Quiescent Current FEATURES DESCRIPTION n Silent Switcher 2 Architecture The LT 8640S/LT8643S synchronous step-down regulator n features second generation Silent Switcher architecture Ultralow EMI Emissions on Any PCB n designed to minimize EMI emissions while delivering high Eliminates PCB Layout Sensitivity n efficiency at high switching frequencies. This includes Internal Bypass Capacitors Reduce Radiated EMI n the integration of bypass capacitors to optimize all the Optional Spread Spectrum Modulation fast current loops inside and make it easy to achieve n High Efficiency at High Frequency advertised EMI performance by reducing layout sensitivity. n Up to 96% Efficiency at 1MHz, 12V to 5V IN OUT This performance makes the LT8640S/LT8643S ideal for n Up to 95% Efficiency at 2MHz, 12V to 5V IN OUT noise-sensitive applications and environments. n Wide Input Voltage Range: 3.4V to 42V n 6A Maximum Continuous, 7A Peak Output Peak current mode control with a 30ns minimum on-time n Ultralow Quiescent Current Burst Mode Operation allows high step-down ratios even at high switching n 2.5A I Regulating 12V to 3.3V (LT8640S) frequencies. The LT8643S has external compensation to Q IN OUT n Output Ripple < 10mV enable current sharing and fast transient response at high P-P n switching frequencies. External Compensation: Fast Transient Response and Current Sharing (LT8643S) Burst Mode operation enables ultralow standby current n Fast Minimum Switch On-Time: 30ns consumption, forced continuous mode can control frequency n Low Dropout Under All Conditions: 100mV at 1A harmonics across the entire output load range, or spread n Forced Continuous Mode spectrum operation can further reduce EMI emissions. n Adjustable and Synchronizable: 200kHz to 3MHz PACKAGE SYNC/MODE 0 V COMP 150C GRADE CLKOUT INTERNAL CAPS C n Output Soft-Start and Tracking LT8640 QFN Pulse-Skipping Internal Yes No No n Small 24-Lead 4mm 4mm LQFN Package LT8640-1 QFN FCM Internal Yes No No n AEC-Q100 Qualified for Automotive Applications LT8640S LQFN FCM Internal No Yes Yes LT8643S LQFN FCM External No Yes Yes APPLICATIONS LT8640S-2 LQFN FCM Internal Yes Yes No n LT8643S-2 LQFN FCM External Yes Yes No Automotive and Industrial Supplies n General Purpose Step-Down All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 8823345. 12V12V to 5V to 5V EfciencyEfficiency IN IN OUT OUT TYPICAL APPLICATION 100 3.2 95 2.8 5V 6A Step-Down Converter 90 EFFICIENCY 2.4 3.3H V OUT V IN 85 2.0 5V V SW IN 5.7V TO 42V 6A 4.7F EN/UV BIAS 80 1.6 LT8640S 10pF 1M 75 1.2 POWER LOSS 100F RT FB 0.8 70 41.2k GND 243k 1MHz, L = 3.3H 65 0.4 2MHz, L = 2.2H 3MHz, L = 1H f = 1MHz SW 8640S TA01a 0 60 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 LOAD CURRENT (A) 8640S TA01b Rev. B 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LT8640S/LT8643S ABSOLUTE MAXIMUM RATINGS (Note 1) V , EN/UV, PG ..........................................................42V Operating Junction Temperature Range (Note 2) IN BIAS ..........................................................................25V LT8640SE/LT8643SE ......................... 40C to 125C FB, TR/SS ................................................................4V LT8640SI/LT8643SI........................... 40C to 125C SYNC/MODE Voltage ...............................................6V Storage Temperature Range .................. 65C to 150C Maximum Reflow (Package Body) Temperature .....260C PIN CONFIGURATION LT8640S LT8643S TOP VIEW TOP VIEW 24 23 22 21 20 19 24 23 22 21 20 19 BIAS 1 18 RT BIAS 1 18 RT 25 26 25 26 INTV 2 17 EN/UV INTV 2 17 EN/UV CC CC GND GND GND GND GND 3 16 GND GND 3 16 GND NC 4 15 NC NC 4 15 NC 27 28 27 28 V 5 GND GND 14 V V 5 GND GND 14 V IN IN IN IN V 6 13 V V 6 13 V IN IN IN IN 7 8 9 10 11 12 7 8 9 10 11 12 LQFN PACKAGE LQFN PACKAGE 24-LEAD (4mm 4mm 0.94mm) 24-LEAD (4mm 4mm 0.94mm) JEDEC BOARD: = 38C/W, (PAD) = 7C/W (Note 3) JEDEC BOARD: = 38C/W, (PAD) = 7C/W (Note 3) JA JC JA JC DEMO BOARD: = 24C/W DEMO BOARD: = 24C/W JA JA EXPOSED PAD (PINS 2528) ARE GND, SHOULD BE SOLDERED TO PCB EXPOSED PAD (PINS 2528) ARE GND, SHOULD BE SOLDERED TO PCB ORDER INFORMATION PACKAGE MSL PART NUMBER PART MARKING* FINISH CODE PAD FINISH TYPE** RATING TEMPERATURE RANGE LT8640SEV PBF 8640S LT8640SIV PBF LQFN (Laminate Package e4 Au (RoHS) 3 40C to 125C with QFN Footprint) LT8643SEV PBF 8643S LT8643SIV PBF AUTOMOTIVE PRODUCTS*** LT8640SEV WPBF 8640S LT8640SIV WPBF LQFN (Laminate Package e4 Au (RoHS) 3 40C to 125C with QFN Footprint) LT8643SEV WPBF 8643S LT8643SIV WPBF Contact the factory for parts specified with wider operating temperature Recommended LGA and BGA PCB Assembly and Manufacturing ranges. *Pad or ball finish code is per IPC/JEDEC J-STD-609. Procedures Device temperature grade is indicated by a label on the shipping container. LGA and BGA Package and Tray Drawings Parts ending with PBF are RoHS and WEEE compliant. **The LT8640S/LT8643S package has the same dimensions as a standard 4mm 4mm QFN package. ***Versions of this part are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. These models are designated with a W suffix. Only the automotive grade products shown are available for use in automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for thesemodels. Rev. B 2 For more information www.analog.com BST FB SW PG SW GND SW TR/SS SW SYNC/MODE SW CLKOUT BST FB SW PG SW V C SW TR/SS SW SYNC/MODE SW CLKOUT