Datasheet LT8640S, LT8643S (Analog Devices)

LT8640S/LT8643S 42V, 6A Synchronous Step-Down Silent Switcher 2 with 2.5µA Quiescent Current
FeaTures DescripTion
n
Silent Switcher
®
2 Architecture
The LT®8640S/LT8643S synchronous step-down regulator n
Ultralow EMI/EMC Emissions on Any PCB
features second generation Silent Switcher architecture n
Eliminates PCB Layout Sensitivity
designed to minimize EMI/EMC emissions while delivering n
Internal Bypass Capacitors Reduce Radiated EMI
high efficiency at high switching frequencies. This n
Optional Spread Spectrum Modulation
includes the integration of bypass capacitors to optimize n
High Efficiency at High Frequency
all the fast current loops inside and make it easy to achieve n advertised EMI performance by reducing layout sensitivity.
Up to 96% Efficiency at 1MHz, 12VIN to 5VOUT
n This performance makes the LT8640S/LT8643S ideal for
Up to 95% Efficiency at 2MHz, 12VIN to 5VOUT
n noise- sensitive applications and environments.
Wide Input Voltage Range: 3.4V to 42V
n
6A Maximum Continuous, 7A Peak Output
The fast, clean, low overshoot switching edges enable high n
Ultralow Quiescent Current Burst Mode
®
Operation
efficiency operation even at high switching frequencies, n
2.5µA IQ Regulating 12VIN to 3.3VOUT (LT8640S)
leading to a small overall solution size. Peak current n
Output Ripple < 10mVP-P
mode control with a 30ns minimum on-time allows high n
External Compensation: Fast Transient Response
step-down ratios even at high switching frequencies.
and Current Sharing (LT8643S)
The LT8643S has external compensation via the VC pin n Fast Minimum Switch On-Time: 30ns to enable current sharing and fast transient response n Low Dropout Under All Conditions: 100mV at 1A at high switching frequencies. A CLKOUT pin enables n Forced Continuous Mode synchronizing other regulators to the LT8640S/LT8643S. n Adjustable and Synchronizable: 200kHz to 3MHz Burst Mode operation enables ultralow standby current n Output Soft-Start and Tracking consumption, forced continuous mode can control n Small 24-Lead 4mm × 4mm LQFN Package frequency harmonics across the entire output load range, or spread spectrum operation can further reduce EMI/
applicaTions
EMC emissions. Soft-start and tracking functionality is n accessed via the TR/SS pin, and an accurate input voltage Automotive and Industrial Supplies UVLO threshold can be set using the EN/UV pin. n General Purpose Step-Down L, LT, LTC, LTM, Linear Technology, the Linear logo, Silent Switcher, Burst Mode and LTspice are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners. Protected by U.S. patents, including 8823345.
Typical applicaTion 12V12V IN IN to 5V to 5VOUT OUT Efficiency Efficiency
100 3.2 95 2.8
5V 6A Step-Down Converter
90 EFFICIENCY 2.4 POWER LOSS (W) 3.3µH VOUT VIN VIN SW 5V 85 2.0 5.7V TO 42V 6A 4.7µF EN/UV BIAS 80 1.6 LT8640S 10pF 1M 75 1.2 EFFICIENCY (%) POWER LOSS RT FB 100µF 70 0.8 41.2k GND 243k 1MHz, L = 3.3µH 65 2MHz, L = 2.2µH 0.4 3MHz, L = 1µH fSW = 1MHz 8640S TA01a 60 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 LOAD CURRENT (A) 8640S TA01b 8640sfa For more information www.linear.com/LT8640S 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Applications Related Parts