30A Buck Controllers Achieve 96% Efficiency, Limit Reverse Current in Paralleled Modules, and Shrink Power-Supply Size
SUNNYVALE, CA-April 6, 2005-Maxim Integrated Products (NASDAQ: MXIM) introduces the MAX5060/MAX5061 PWM buck controllers. These PWM controllers allow the design of high-output-current, compact power supplies with a minimum number of external components. The devices' internal voltage regulators allow operation from a 5V, 12V, or 24V power bus, while the output voltage is adjustable from 0.6V to 5.5V. The MAX5060/MAX5061 are well suited for applications requiring up to 30A output current. Multiple DC-DC controller modules can, moreover, be paralleled to achieve higher output currents.
Both devices include an average-current-mode control scheme, which allows designers to achieve current-limit as well as current-sharing accuracy of typically ±10%. This capability results in a small inductor and small, or fewer, external MOSFETs, thus reducing power-supply size and cost. An external current-sense resistor ensures that ±10% (typical) current-sharing accuracy is maintained between paralleled modules. The current-sense threshold for both devices is only 25mV, which reduces power dissipation in the sense resistor and allows use of a smaller sense resistor (2010 size resistor for a 20A power supply) than competitive solutions. The MAX5060/MAX5061 also limit reverse-current sinking, thus preventing the main power bus (VBUS) from being pulled down when multiple power-supply modules are paralleled.
Both the MAX5060 and MAX5061 include ON/OFF input and external frequency synchronization. Switching frequency is externally programmable from 125kHz to 1.5MHz, thus allowing power-supply designers to optimize power-supply size and efficiency.
The MAX5060 includes additional features: a clock-output signal to drive a second DC-DC converter 180 degree out-of-phase, a load-monitoring output voltage proportional to the output current, power-good output, overvoltage protection, and differential remote-sense pins to ensure precise voltage at the load. A 20A power-supply evaluation kit that measures 42mm x 23mm and achieves 96% peak efficiency is available from the company.
The MAX5060/MAX5061 operate over the -40 degrees Celsius to +125 degrees Celsius temperature range. The MAX5060 is available in a thermally enhanced 28-pin TQFN and priced at $1.66, while the MAX5061 is available in a 16-pin TSSOP package and priced at $1.44 (1000-up, FOB USA).
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