ISOLATED/NONISOLATED CURRENT-MODE PWM CONTROLLERS WORK WITH UNIVERSAL OFFLINE, TELECOM, OR 12V INPUT VOLTAGE
SUNNYVALE, CA-November 6, 2002-Maxim Integrated Products (NASDAQ:MXIM) introduces the MAX5052/MAX5053 current-mode PWM controllers. The MAX5052 operates from a rectified universal offline or telecom (36V to 72V) input voltage while the MAX5053 operates from 10.8V to 24V input voltage. An internal bias regulator eases the use of these devices with loosely regulated voltages obtained from bias windings.
The MAX5052/MAX5053 include an error amplifier, assisting in the design of isolated or nonisolated power supplies. Used with primary-side regulation, these devices eliminate the cost of an optocoupler, as well as a shunt reference on the secondary side. This makes them especially useful for low-cost, isolated power-supply designs. A fixed 262kHz switching frequency is trimmed to ±12% accuracy, which allows for compact power supplies using all surface-mount components.
Ideal for use in wide-input-voltage range isolated or nonisolated power supplies, the MAX5053 is also well suited for use as a 12V boost regulator, 12V sepic regulator, or 12V input-isolated power supply.
Both devices feature an ultra-low 45µA startup current, allowing the use of high-value 1/4Ω startup resistors and low-value ceramic startup capacitors. Power-supply startup is fast while dissipation is substantially reduced, even when operating from a rectified 120VAC line. An input voltage undervoltage lockout (UVLO) lets the designer set the input start voltage using an external resistor divider. Furthermore, the device can be shut down by pulling the UVLO pin low.
The MAX5052/MAX5053 include digital soft-start for the reference voltage to the internal error amplifier. This results in superior control of the output-voltage rise during initial startup under any load conditions. This also eliminates virtually all output-voltage overshoots. Both devices include thermal shutdown and are available with a 50% or 75% duty cycle.
Rated for operation at the extended temperature range (-40°C to +85°C), the MAX5052/MAX5053 are available in a surface-mount 8-pin µMAX package. Prices start at $0.63 (1000-up, FOB USA).
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