42V, 6A Synchronous Step-Down Silent Switcher 2 with 2.5μA Quiescent Current

The LT®8640S/LT8643S/LT8640SA/LT8643SA 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 bypass 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 LT8640S/LT8643S/LT8640SA/LT8643SA ideal for noise-sensitive applications and environments.

Peak current mode control with a 30ns minimum on-time allows high step-down ratios even at high switching frequencies. The LT8643S/LT8643SA has external compensation to enable current sharing and fast transient response at high switching frequencies.

Burst Mode operation enables ultralow 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.

Applications

* Automotive and Industrial Supplies

* 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, 12VIN to 5VOUT

* Up to 95% Efficiency at 2MHz, 12VIN to 5VOUT

* Wide Input Voltage Range: 3.4V to 42V

* Output Voltage Range: 0.97V to 10V(LT8640S/LT8643S); 0.97V to (VIN – 0.5V) (LT8640SA/LT8643SA)

* 6A Maximum Continuous, 7A Peak Output

* Ultralow Quiescent Current Burst Mode® Operation

* 2.5µA IQ Regulating 12VIN to 3.3VOUT (LT8640S/LT8640SA)

* Output Ripple < 10mVP-P