5 A Synchronous Step-Down Device w/ 2.5 μA Quiescent Current



The LT®8640/LT8640-1 step-down regulator features Si-lent Switcher architecture designed to minimize EMI/EMC emissions while delivering high efficiency at frequencies up to 3MHz. An ultralow 2.5μA quiescent current—with the output in full regulation—enables applications requiring highest efficiency at very small load currents.The LT86 40/LT86 40-1 allows high VIN to low VOUT conversion at high frequency with a fast minimum top switch on-time of 30ns. The SYNC/MODE pin selects between Burst Mode operation, spread spectrum mode, synchronization to an external clock, and either pulse-skipping (LT86 40) or forced continuous mode (LT86 40-1 ).

• Silent Switcher Architecture
  - Ultralow EMI/EMC Emissions
  - Spread Spectrum Frequency Modulation
• High Efficiency at High Frequency
  - Up to 96% Efficiency at 1MHz, 12VIN to 5VOUT
  - Up to 95% Efficiency at 2MHz, 12VIN to 5VOUT
• Wide Input Voltage Range: 3.4V to 42V
• 5A Maximum Continuous Output, 7A Peak Transient Output
• Ultralow Quiescent Current Burst Mode Operation
  - 2.5μA IQ Regulating 12VIN to 3.3VOUT
  - Output Ripple < 10mVP-P
• Fast Minimum Switch On-Time: 30ns
• Low Dropout Under All Conditions: 100mV at 1A
• Forced Continuous Mode (LT8640-1 Only)
• Safely Tolerates Inductor Saturation in Overload
• Adjustable and Synchronizable: 200kHz to 3MHz
• Peak Current Mode Operation
• Output Soft-Start and Tracking
• Small 18-Lead 3mm × 4mm QFN and Side Wettable QFN

• Automotive and Industrial Supplies
• General Purpose Step-Down
• GSM Power Supplies

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