LTC7821 features

LTC7821 is a highly efficient DC-to-DC converter from Analog Devices.

LTC7821 operates at a wide input voltage range of 10V to 72V (absolute maximum rating of 80V) and can control several 10 of amperes with external components and an output voltage range of 0.9V to 33.5V.

LTC7821 is the industry's first "hybrid step-down synchronous controller" that integrates a switched capacitor circuit and a step-down synchronous controller.

There are 3 main features.

1. Analog Devices' original software switch function
Soft switching reduces EMI and MOSFET stress.

2. Small, space-saving 5mm x 5mm QFN package
This is a small package with freedom to implement as an intermediate bus power supply.

3. High efficiency 97% in the 240W class, which is not available elsewhere.
Ideal for small solutions with 240W insulated power supply

Up to 50% reduction in mounting area on board

Normally, in order to reduce the voltage from 48V to 1.2V or 3.3V used in the substrate, a 2 step procedure is required, in which the voltage is first reduced to an intermediate potential of 5 V to 12V and then reduced to 1.2V or 3.3V. As a result, the substrate size tends to increase.

Traditional Configuration

However, in  LTC7821, the "Hybrid Step-down Synchronous Controller", which integrates a switched capacitor circuit and a step-down synchronous controller, can reduce the voltage to the intermediate potential and the voltage to 1.2V or 3.3V in a single circuit, thus reducing the mounting area by 50%.

Hybrid Step-down Synchronous Controller combines switched capacitor circuit and step-down synchronous controller
 

High efficiency (97%) from 48V to 12V / 20A high voltage power supply

This is achieved by increasing the switching frequency by a factor of 3 or more without sacrificing efficiency with our unique Hybrid Step-down Synchronous Controller.

Higher efficiency not only reduces power loss, but also reduces heat generation due to power loss, thus reducing the impact on peripheral circuits.

Efficiency at 12V output

Furthermore, by increasing the switching frequency, the capacitors and inductances of peripheral components can be reduced, and further space saving can be expected.

Parallel connection for high power applications

Multiple LTC7821 can be connected in parallel to operate in a multiphase configuration, doubling the output current, allowing for higher power applications.

Target application

• Intermediate bus converter
• High current power supply system
• Various systems for telecommunications, data communications and storage
• 48V Automotive Systems

Product Specification

• Input voltage range: 10V to 72V, absolute maximum rating : 80V
• Output voltage range: 0.9V to 33.5V
• Up to 97% efficiency at 500kHz
• Soft switching for low EMI and MOSFET stress reduction
• Supports multi-phase configuration with parallel connections
• Input current detection and overcurrent protection
• 32-Pin (5mm × 5mm) QFN