Analog Devices 72V Hybrid Step-Down DC / DC Controller Delivers Solution Size 50%

Analog Devices, Inc. (ADI) announced the LTC7821, Power by Linear ™, the industry's first hybrid step-down synchronous controller that combines a switched-capacitor circuit with a synchronous buck controller DC / DC converter solution size dropped 50% compared to traditional buck solutions. This improvement is achieved by increasing the switching frequency by three times (without sacrificing efficiency). Or, when working on the same frequency, the LTC7821-based solution provides up to 3% efficiency gain. Other benefits of the LTC7821 include low EMI and reduced MOSFET stress due to the soft-switching front end, making it ideal for next-generation, non-isolated intermediate bus applications in power distribution, data and telecommunications, and emerging 48V automotive applications.

Analog Devices' 72V Hybrid Step-Down DC / DC Controller Delivers Solution Size 50%

The LTC7821 operates over an input voltage range of 10V to 72V (80V absolute maximum) and generates an output voltage of 0.9V to 33.5V and tens of amperes (depending on the choice of external components). In a typical 48V to 12V / 20A application, 97% efficiency is achieved when the LTC7821 switches at 500kHz. However, the conventional synchronous buck converter achieves the same efficiency only by performing a switching operation at 1/3 of the operating frequency, resulting in the necessity of using much larger magnetic components and output filter components. The external MOSFET performs switching operations at a fixed frequency and can be set from 200kHz to 1.5MHz. The LTC7821's robust 1Ω N-Channel MOSFET gate driver maximizes efficiency and drives multiple MOSFETs in parallel to meet the needs of higher power applications. Because the LTC7821 employs a current mode control architecture, multiple LTC7821s operate in a multi-phase configuration in parallel, allowing them to achieve much more power with their superior current sharing capability.

The LTC7821 implements many proprietary protection features to achieve rugged performance in a wide range of applications. The LTC7821-based design eliminates the inrush current typically caused by switched capacitor circuits by pre-balancing the capacitors during startup. In addition, the LTC7821 detects faults by monitoring system voltage, current and temperature and uses a sense resistor to provide overcurrent protection. When a fault condition occurs, the device stops switching and pulls the / FAULT pin low. A built-in timer can be set for the appropriate restart / retry time. The EXTVCC pin allows the LTC7821 to rely on the lower voltage output of the converter or other available power supply up to 40V, reducing power consumption and improving efficiency.

The LTC7821 is available in a 5mm x 5mm QFN-32 package. Extended and Industrial Temperature Versions Operable from -40 ° C to 125 ° C.

LTC7821 product features

Wide VIN Range: 10V to 72V, 80V Absolute Maximum
VOUT Range: 0.9V to 33.5V
Solution size dropped by 50%
Soft switches are used to achieve low EMI and reduce MOSFET stress
Efficiency up to 97% (at 500kHz)
PLL fixed frequency: 200kHz to 1.5MHz
Clock output for multi-phase operation
Powerful Quad N-Channel MOSFET Gate Driver
Input current detection and overcurrent protection
Programmable timer and retry short circuit protection

Price and delivery

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Author：Brittany Antonia （The author of article owns the copyright.）