Quick-PWM SLAVE CONTROLLERS FOR MULTIPHASE, STEP-DOWN CPU SUPPLIES
SUNNYVALE, CA-November 29, 2001-Maxim Integrated Products introduces the MAX1887/MAX1897 step-down slave controllers intended for low-voltage, high-current, multiphase DC-to-DC applications. The MAX1887/MAX1897 slave controllers can be combined with any of Maxim’s DC-to-DC converters. Existing Quick-PWM™ controllers, such as the MAX1718, function as the master controller, providing accurate output voltage regulation, fast transient response, and fault-protection features. Synchronized to the master’s low-side gate driver, the MAX1887/MAX1897 include the Quick-PWM constant on-time controller with gate drivers for a synchronous rectifier, active current balancing, and precision current-limit circuitry.
The MAX1887/MAX1897 provide the same high efficiency, ultra-low duty factor capability, and excellent transient response as other Quick-PWM controllers. The MAX1887/MAX1897 accurately balance the inductor currents and provide precise current-limit protection. The dual-purpose current-limit input also allows the slave controller to automatically enter a low-power standby mode when the master controller shuts down.
The MAX1887 triggers on the rising edge of the master’s low-side gate driver, which staggers the on–times of both master and slave, providing out-of-phase operation that can reduce the input ripple current, and consequently the number of input capacitors. The MAX1897 features a selectable trigger polarity, allowing out-of-phase or simultaneous in-phase operation.
The MAX1897 is available in 20-pin QFN packages, and the MAX1887 is available in a 16-pin QSOP package. All devices are screened for the extended temperature range (-40°C to +85°C). Prices start at $2.24 (1000-up, FOB USA). To reduce design time a preassembled Master/Slave MAX1718 EVKIT (evaluation kit) is available with recommended external components.
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