The **LTC3891** is a high-voltage synchronous step-down DC/DC controller introduced by **Linear Technology Corporation**. Designed for demanding applications, this device offers exceptional performance with a quiescent current of just 50µA in standby mode and stable output operation. It supports an input voltage range from 4V to 60V, making it highly resilient to voltage transients and ideal for use in cold-start scenarios. This wide input range allows compatibility with various power sources and battery chemistries, including 12V, 24V, and 48V systems.
With output currents up to 20A and efficiency as high as 95%, the LTC3891 provides flexible output voltage settings from 0.8V to 24V. Its versatility makes it suitable for automotive, industrial, heavy equipment, robotics, and telecommunications applications. The device features a powerful 1.1Ω internal MOSFET gate driver, ensuring reliable performance under different load conditions.
The LTC3891 operates at a fixed frequency ranging from 50kHz to 900kHz and can synchronize with an external clock between 75kHz and 850kHz via its phase-locked loop (PLL). Users can choose between continuous, pulse skip, or low-ripple Burst Mode operation depending on their application needs. Its current-mode architecture simplifies loop compensation, delivers fast transient response, and ensures excellent voltage regulation.
For current sensing, the LTC3891 uses either the voltage drop across the output inductor (DCR) for maximum efficiency or an optional sense resistor. Current foldback protection helps reduce heat generation during overload conditions. Additional features include a short 95ns minimum on-time for high step-down ratios, up to 99% duty cycle for low dropout output, and an internal LDO for the gate driver. A power-good signal is also included for system monitoring.
The LTC3891 is available in two thermally enhanced packages: a 20-lead 3mm x 4mm QFN and a 20-lead TSSOP. It comes in three temperature grades: extended and industrial (-40°C to 125°C), automotive (-40°C to 150°C), and military (-55°C to 150°C). The unit price for 1,000 pieces is $3.47 each.
**Key Features:**
- Wide input voltage range: 4V to 60V
- Ultra-low quiescent current: 50µA
- Adjustable output voltage: 0.8V to 24V
- High efficiency: Up to 95% with synchronous rectification
- Very short 95ns minimum on-time
- DCR or RSENSE current detection
- Optional Burst Mode, Pulse Skip, or Continuous operation
- Fixed frequency range: 50kHz to 900kHz
- PLL synchronization: 75kHz to 850kHz
- Fast transient response with easy loop compensation
- Soft start and tracking options
- Overvoltage and overcurrent protection
- Multiple temperature grades available
**Photo Description:** High-voltage DC/DC synchronous controller
**Image:** [Link](http://i.bosscdn.com/blog/20/17/11/2916635215622.png)
**Performance Summary: LTC3891**
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