LOW-COST, THREE AND FIVE OUTPUT xDSL AND CABLE MODEM POWER SUPPLIES
SUNNYVALE, CA-May 24, 2001-Maxim Integrated Products introduces the MAX1864 and MAX1865 power-supply ICs, used to build the lowest-cost xDSL and cable modem consumer premises equipment (CPE) power supplies. They integrate a high-efficiency step-down DC-DC controller and two to four linear regulator controllers to provide all the required voltages for CPE equipment.
The current-mode step-down controller uses an external dual N-channel MOSFET to provide low-cost synchronous rectification for high efficiency and low heat. To further save cost, no external current-sense resistor is required. Switching frequencies of 100kHz and 200kHz permit the use of low-cost magnetics and aluminum electrolytic capacitors. The linear regulator controllers drive inexpensive external bipolar junction transistors (BJTs).
MAX1864 integrates a step-down controller and two positive LDO controllers. For xDSL applications, it generates three outputs for I/O, core, and positive line drive supplies. For cable modem applications, it generates the core, I/O, and analog supplies.
The MAX1865 integrates a step-down controller, three positive LDO controllers, and one negative LDO controller. For xDSL applications, it generates five outputs for I/O, core, and bipolar line driver supplies.
Current-mode controls offer good transient response. Adjustable current limit is provided for protection. The step-down output is preset to 3.3V, or it can be adjusted from 1.25V to 5V using a feedback resistor divider.
The positive regulator voltages can be set from 1.25V to 15V, and negative regulator voltage can be set from -1.25V to -15V using external feedback resistors. All positive regulators are soft-started, and the POK pin monitors all outputs.
The MAX1864EEE comes in a 16-pin QSOP package with prices starting at $1.75 (1000-up, FOB USA). The MAX1865EEP comes in a 20-pin QSOP package with prices starting at $2.05 (1000-up, FOB USA). These devices are specified for the extended-industrial temperature range (-40°C to +85°C). Evaluation kits for the MAX1864 and the MAX1865 are available to speed designs.
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