42V, 5A Silent Switcher More Power & Spread Spectrum ® 100 3.00 95 VOUT 2.63 90 LT8640 2.25 Efficiency 85 1.88 80 1.50 75 1.13 70 60 0.5 0.75 12VIN to 5VOUT 1MHz 2MHz 65 1 1.5 2 2.5 3 3.5 Load Current (A) 4 4.5 Power Loss (W) Efficiency (%) VIN 0.38 5 0 Actual Size Demo Circuit Low EMI/EMC Passes CISPR25 Class 5, 95% Efficient at 2MHz The LT®8640 joins our growing family of ultralow quiescent current high voltage monolithic synchronous buck regulators. Its inherent ultralow EMI/EMC emissions, coupled with spread spectrum capabilities, allows it to comfortably meet CISPR25 class 5 radiated emissions requirements for automotive environments. The LT8640 consumes only 2.5µA of quiescent current while regulating an output of 3.3V from a 12V input source. It also delivers up to 5A of output current with efficiencies as high as 96%. Features • Ultralow EMI/EMC Emissions • Spread Spectrum Frequency Modulation • Input Voltage: 3.4V to 42V • Ultralow Quiescent Current in Standby: 2.5µA • Low Dropout: 100mV at 1A All Conditions • Small 3mm x 4mm QFN Package www.linear.com/product/LT8640 1-800-4-LINEAR , LT, LTC, LTM, Linear Technology, the Linear logo and Silent Switcher are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners Simplified LT8640 EMI/EMC Curve, IOUT = 4A 50 45 40 Amplitude (dBuV/m) 35 30 25 20 15 10 5 CISPR25 Class 5 Pk Limit LT8640 Fixed Frequency Mode LT8640 Spread Spectrum Mode 0 -5 0 100 200 300 Frequency (MHz) 400 500