LT8645SA

RECOMMENDED FOR NEW DESIGNS

65V, 8A Synchronous Step-Down Silent Switcher 2 with 2.5μA Quiescent Current

Analog Devices LT8645SA Product Info

10 February 2026 6

Features

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 94% Efficiency at 400kHz, 24V_IN to 5V_OUT
Up to 93% Efficiency at 1MHz, 24V_IN to 5V_OUT

Wide Input Voltage Range: 3.4V to 65V
Wide Output Voltage Range: 0.97V to (V_IN - 0.5V)
Ultralow Quiescent Current Burst Mode Operation

2.5μA I_Q Regulating 12V_IN to 3.3V_OUT (LT8645SA)
Output Ripple < 10mV_P-P

External Compensation: Fast Transient Response and Current Sharing (LT8646SA)
Robust High V_OUT Operation

Safely Tolerates High Reverse Current

Fast Minimum Switch On-Time: 40ns
Low Dropout Under All Conditions: 60mV at 1A
Adjustable and Synchronizable: 200kHz to 2.2MHz
Output Soft-Start and Tracking
Small 32-Lead 6mm × 4mm LQFN Package
AEC-Q100 Qualified for Automotive Applications

Part details & applications

The LT^®8645SA/LT8646SA 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 eliminating layout sensitivity.

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 40ns minimum ontime allows high step-down ratios even at high switching frequencies. The LT8646SA 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
General Purpose Step-Down

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