LT8638S Datasheet

• Silent Switcher^®2 Architecture
  • Ultralow EMI Emissions on Any PCB
  • Eliminates PCB Layout Sensitivity
  • Internal Bypass Capacitors Reduce Radiated EMI
  • Optional Spread Spectrum Modulation
• High Efficiency at High Frequency
  • Up to 96% Efficiency at 1MHz, 12V_IN to 5V_OUT
  • Up to 94% Efficiency at 2MHz, 12V_IN to 5V_OUT
• Wide Input Voltage Range: 2.8V to 42V
• 10A Maximum Continuous, 12A Peak Transient Output
• Reference Accuracy: ±1% Over Temperature
• Fast Transient Response with External Compensation
• Low Quiescent Current Burst Mode^® Operation
  • 90µA I_Q Regulating 12V_IN to 5V_OUT
  • Output Ripple < 10mV_P-P
• Fast Minimum Switch On-Time: 25ns
• PolyPhase^® Operation: Up to 12 Phases
• Low Dropout Under All Conditions: 45mV at 1A
• Adjustable and Synchronizable: 200kHz to 3MHz
• Output Soft-Start and Power Good
• Safely Tolerates High Reverse Current
• 28-Lead 5mm × 4mm LQFN Package
• AEC-Q100 Qualified for Automotive Applications

• Automotive and Industrial Supplies
• General Purpose Step-Down

The LT8638S synchronous step-down regulator features second generation Silent Switcher architecture designed to minimize EMI emissions while delivering high efficiency at high switching frequencies. This includes the integration of input capacitors to optimize all the fast current loops inside and make it easy to achieve advertised EMI performance by reducing layout sensitivity. This performance makes the LT8638S ideal for noise sensitive applications and environments.

The fast, clean, low overshoot switching edges enable high efficiency operation even at high switching frequencies, leading to a small overall solution size. Peak current mode control with a 25ns minimum on-time allows high step down ratios even at high switching frequencies. External compensation via the V_C pin allows for fast transient response. PolyPhase operation allows multiple LT8638S regulators to run with interleaving phase shift to provide more output current.

Burst Mode operation enables low standby current consumption, forced continuous mode can control frequency harmonics across the entire output load range, or spread spectrum operation can further reduce EMI emissions. Soft-start and tracking functionality is accessed via the SS pin, and an accurate input voltage UVLO threshold can be set using the EN/UV pin.