72V Fixed-Ratio DC/DC Controller Without Power Inductor Requirement
Provides 500W in non-isolated intermediate bus converter applications

Analog Devices announced the release of the new LTC7820, a high-power fixed-ratio charge pump DC/DC controller. By eliminating the power inverter from non-isolated intermediate bus converters, this product can reduce circuit size by up to 50% and provide a power density of up to 4,000 W/in³. The LTC7820 drives external MOSFETs with up to 99% efficiency in voltage dividers, doublers, or inverters. Its open-loop fixed 50% duty cycle operation makes it ideal for non-isolated intermediate bus applications in power distribution, datacom, telecom, high-end computing, and industrial systems.

The LTC7820 operates over an input voltage range of 6V to 72V (up to 80V abs) and can provide dozens of different output current values depending on the topology and the use of external components. This product can be configured with a 2:1 step-down ratio from an input voltage of up to 72V. A 4:1 step-down ratio is possible by connecting two LTC7820 ICs in a cascade configuration. For higher step-down ratios, such as 6:1, the Dickson converter topology is recommended; this is achievable with just a single LTC7820 product and is ideal for 54V input to 9V output.

In addition, it can be configured with a 1:2 step-up ratio or a 1:1 inverter ratio from a high input voltage of 36V. The external MOSFET switches at a fixed frequency that is programmable within the range of 100kHz to 1MHz. The powerful 1.1Ω N-channel MOSFET gate driver of the LTC7820 can drive multiple MOSFETs connected in parallel for high-power applications, maximizing efficiency.



The LTC7820 monitors system voltage, current, and temperature in relation to faults and provides overcurrent protection using a sense resistor. When a fault condition occurs, it stops switching and pulls the /FAULT pin low. An onboard timer can set appropriate restart/retry times. The EXTVCC pin reduces power consumption and improves efficiency by allowing the LTC7820 to be powered from the converter's lower voltage output or a possible source up to 40V.

In addition, it provides features such as soft switching for low EMI, power good output signal, undervoltage lockout, and internal charge balance circuit.

The LTC7820 is available in a 4mm x 5mm QFN-28 package. The industrial temperature version has an extended temperature range of –40 to 125°C.