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Home > News > Industry News > ADI hits 500W with switched ca.....

ADI hits 500W with switched capacitor power converter

  • Author:Ella Cai
  • Release on:2017-06-20
Analogue Devices has managed to create a 500W switched-capacitor power chip for fixed ratio power conversion at up to 72V and 99% efficiency.

Power density up to 4000W/in3 is claimed.

The main application foreseen for the chip, the LTC7820, is 48V non-isolated dc bus conversion, although it is capable of up, down and inverting conversion at a variety of ratios. An example (see diagram below) is a 50A 54 to 9V (6:1) converter peaking at 98% efficiency at 20A.

“Two LTC7820 IC’s can be cascaded for a 4:1 step-down ratio,” said ADI. “For even higher step-down ratios, such as a 6:1, the Dickson converter topology is recommended and is ideal for 54V input to a 9V outputs, requiring only a single LTC7820. ”

LTC7820 54 to 9V converter6:1 down conversion at up to 98% efficiency

At least four external n-channel mosfets are required, for which the chip includes four powerful (1.1Ω) gate drivers.

Vin max for divide-by-two is 72V, while for doubling and inversion it is 36V. Minimum operating voltage is 6V.
An separate power pin allows the chip to be powered from the stepped-down output, or other available sources up to 40V, reducing power dissipation and improving efficiency.

Switching frequency range is 100kHz to 1MHz.
LTC7820 pcbOther features include: soft-start, input current sensing and protection for: over-current, short-circuit, over-voltage and under-voltage.

“It stops switching and pulls the /Fault pin low when a fault condition occurs,” said ADI. “An onboard timer can be set for appropriate re-start/re-try times.”
Package is 4 x 5mm QFN-28, and it operates across -40 to 125°C.