SECONDARY-SIDE, SYNCHRONOUS-RECTIFIER DRIVERS INTEGRATE SHUNT REFERENCE, CURRENT SHARING, AND VOLTAGE MARGINING
SUNNYVALE, CA-October 27, 2003-Maxim Integrated Products
(NASDAQ: MXIM) introduces the MAX5058/MAX5059 secondary-side, synchronous-rectifier driver ICs that enable secondary-side synchronous rectification in isolated power supplies. These devices integrate all the secondary-side circuitry required for high-efficiency, low-output-voltage power supplies.
The MAX5058/MAX5059 integrate the following functions: gate drive for secondary-side synchronous MOSFETs; a flexible current-output reference capable of generating output voltages as low as 0.5V; a low 200mV dropout shunt error amplifier; a remote-load voltage-sense amplifier; an integrated voltage-margining circuit; and a current-sharing circuit, which allows paralleling of multiple power supplies for higher output current. Both devices regulate their gate-drive voltage from an unregulated supply voltage of 4.5V to 28V. An overtemperature-warning-flag open-drain output can be used in conjunction with an optocoupler to signal the primary-side controller to shutdown in the event of excessive power dissipation in the IC.
The MAX5058/MAX5059 are specifically designed to work with the MAX5051 primary-side isolated PWM controller and the MAX5042/MAX5043 isolated PWM converters (with internal power MOSFETs). The combination of these primary-side and secondary-side ICs simplify isolated power-supply design, allow the design of compact power supplies, reduce bill-of-materials cost, and offer very high reliability. For example, a 50W isolated, 48V, power-supply design can be completed with only the MAX5042/MAX5058, two optocouplers, and a few additional components. When used with the MAX5051, the primaries of two paralleled power supplies can be synchronized and operate 180° out-of-phase, thus reducing input-ripple current and the number of input capacitors.
The MAX5058 provides a 5V gate drive, whereas the MAX5059 provides a 10V gate drive for secondary-side MOSFETs. Both devices operate over a wide -40°C to +125°C temperature range and are available in a thermally enhanced, surface-mount, 28-pin TSSOP package capable of dissipating 1.9W. Prices start at $2.96 (1000-up, FOB USA).
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