POWER LOSS (W) LT8640S-2/LT8643S-2 42V, 6A Synchronous Step-Down Silent Switcher with 2.5A Quiescent Current FEATURES DESCRIPTION n Silent Switcher Architecture The LT 8640S-2/LT8643S-2 synchronous step-down n regulator features Silent Switcher architecture designed Ultralow EMI Emissions n to minimize EMI emissions while delivering high efficiency Optional Spread Spectrum Modulation n at high switching frequencies. Peak current mode control High Efficiency at High Frequency n with a 30ns minimum on-time allows high step-down Up to 96% Efficiency at 1MHz, 12V to 5V IN OUT ratios even at high switching frequencies.The LT8643S-2 n Up to 95% Efficiency at 2MHz, 12V to 5V IN OUT has external compensation to enable current sharing and n Wide Input Voltage Range: 3.4V to 42V fast transient response at high switching frequencies. n 6A Maximum Continuous, 7A Peak Output n Ultralow Quiescent Current Burst Mode Operation Burst Mode operation enables ultralow standby current n 2.5A I Regulating 12V to 3.3V (LT8640S-2) consumption, forced continuous mode can control Q IN OUT n Output Ripple < 10mV frequency harmonics across the entire output load range, P-P n External Compensation: Fast Transient Response or spread spectrum operation can further reduce EMI and Current Sharing (LT8643S-2) emissions. n Fast Minimum Switch On-Time: 30ns SYNC/ 150C INTERNAL n Low Dropout Under All Conditions: 100mV at 1A PACKAGE MODE 0 V COMP GRADE CLKOUT CAPS C n Forced Continuous Mode Pulse- LT8640 QFN Internal Yes No No n Skipping Adjustable and Synchronizable: 200kHz to 3MHz n Output Soft-Start and Tracking LT8640-1 QFN FCM Internal Yes No No n Small 24-Lead 4mm 4mm LQFN Package LT8640S LQFN FCM Internal No Yes Yes n AEC-Q100 Qualified for Automotive Applications LT8643S LQFN FCM External No Yes Yes LT8640S-2 LQFN FCM Internal Yes Yes No APPLICATIONS LT8643S-2 LQFN FCM External Yes Yes No n Automotive and Industrial Supplies All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 8823345. n General Purpose Step-Down TYPICAL APPLICATION 12V to 5V Efficiency 5V, 6A Step-Down Converter IN OUT 100 3.2 V IN 5.7V TO 42V 95 2.8 EN/UV V V 4.7F IN IN 90 EFFICIENCY 2.4 1F 1F GND GND 85 2.0 LT8640S-2 80 1.6 BST 0.1F 3.3H V OUT 75 1.2 SW 5V 6A POWER LOSS BIAS 70 0.8 INTV CC 10pF 1M 1MHz, L = 3.3H 1F 65 0.4 2MHz, L = 2.2H RT FB 100F 3MHz, L = 1H 60 0 41.2k GND 243k 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 LOAD CURRENT (A) 8640s2 TA01b f = 1MHz 8640s2 TA01a SW Rev. A 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LT8640S-2/LT8643S-2 ABSOLUTE MAXIMUM RATINGS (Note 1) V , EN/UV, PG ..........................................................42V Operating Junction Temperature Range (Note 2) IN BIAS ..........................................................................25V LT8640S-2E/LT8643S-2E .................. 40C to 125C FB, TR/SS ................................................................4V LT8640S-2I/LT8643S-2I .................... 40C to 125C SYNC/MODE Voltage ...............................................6V LT8640S-2H/LT8643S-2H ................. 40C to 150C Storage Temperature Range .................. 65C to 150C Maximum Reflow (Package Body) Temperature .....260C PIN CONFIGURATION LT8640S-2 LT8643S-2 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 14 V V 5 14 V GND GND GND GND 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, = 7C/W (NOTE 3) JEDEC BOARD: = 38C/W, = 7C/W (NOTE 3) JA JC(PAD) JA JC(PAD) DEMO BOARD: = 24C/W DEMO BOARD: = 24C/W JA JA EXPOSED PAD (PINS 25 TO 28) ARE GND, SHOULD BE SOLDERED TO PCB EXPOSED PAD (PINS 25 TO 28) ARE GND, SHOULD BE SOLDERED TO PCB Rev. A 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