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PWM controllers cut component count

Posted: 07 Apr 2005 ?? ?Print Version ?Bookmark and Share

Keywords:maxim integrated products? max5060? max5061? pwm buck controller? pwm controller?

Maxim Integrated Products claims that its new PWM buck controllers allow the design of high-output-current, compact power supplies with a minimum number of external components.

The MAX5060 and MAX5061's 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. These products are suited for applications requiring up to 30A output current. Multiple dc-dc controller modules can, moreover, be paralleled to achieve higher output currents.

Both the MAX5060 and MAX5061 include an average-current-mode control scheme, which allows designers to achieve current-limit as well as current-sharing accuracy of typically 10 percent. This capability results in a small inductor and small, or fewer, external MOSFETs, thus reducing power-supply size and cost, said Maxim. Additionally, an external current-sense resistor ensures that 10 percent (typical) current-sharing accuracy is maintained between paralleled modules. The current-sense threshold for both devices is 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 new products also limit reverse-current sinking, preventing the main power bus (VBUS) from being pulled down when multiple power-supply modules are paralleled.

The two PWM controllers include ON/OFF input and external frequency synchronization. Switching frequency is externally programmable from 125kHz to 1.5MHz, allowing power-supply designers to optimize power-supply size and efficiency.

The MAX5060 includes additional features, including a clock-output signal to drive a second dc-dc converter 180 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 42-by-23mm and achieves 96 percent peak efficiency is available from the company.

Operating over the -40C to 125C temperature range, the MAX5060 is available in a thermally enhanced 28-pin TQFN and is priced at $1.66, and the MAX5061 is housed in a 16-pin TSSOP package and is available for $1.44 (1,000-up, FOB USA).

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