LTC3643

RECOMMENDED FOR NEW DESIGNS

2A Bidirectional Power Backup Supply

Analog Devices LTC3643 Product Info

10 February 2026 5

Features

Bidirectional Synchronous Boost Capacitor Charger/Buck Regulator for System Backup
Wide Input Voltage Range: 3V to 17V
Up to 40V Capacitor Voltage Storage for High Energy Backup
2A Maximum CAP Charge Current
Integrated Power N-Channel MOSFETs (150mΩ Top and 75mΩ Bottom)
Integrated Power N-Channel MOSFET for Output/CAP Disconnect (50mΩ)

Input Current Limit During Charging
Fast 1MHz Switching Frequency
±1% Reference Accuracy for System Voltage Regulation
Indicator Outputs for Charge Status and Input Power Fail
Low Profile 24-lead 3mm × 5mm QFN Package
AEC-Q100 Qualified for Automotive Applications

Part details & applications

The LTC3643 is a bidirectional synchronous step-up charger and step-down converter which efficiently charges a capacitor array up to 40V from an input supply between 3V to 17V. When the input supply falls below the programmable power-fail threshold, the step-up charger operates in reverse as a synchronous step-down regulator to power the system rail from the backup capacitor during this power interuption/failure condition.

When charging the backup capacitor, an external low-value sense resistor may be used to maintain an accurate current limit from the input supply or implement PowerPath^™ functionality.

The step-down converter operates at a 1MHz switching frequency, allowing small external components to be used. Low quiescent current during regulation maximizes the energy usage from the backup capacitor.

Applications

Backup Capacitor Systems
Power Failure Backup Systems
Solid-State Drives
Automotive

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