LOWEST COST, THREE- AND FIVE-OUTPUT MODEM SUPPLIES WITH SEQUENCING AND TRACKING
SUNNYVALE, CA-August 16, 2001-Maxim Integrated Products introduces the MAX1964T/MAX1965T power-supply controller ICs to build the lowest cost sequencing or tracking power supplies for broadband consumer premises equipment (CPE) operating from a low-cost, unregulated wall-adapter supply. A high-efficiency step-down controller and multiple LDO controllers are integrated to provide all required voltages.
The MAX1964T integrates a synchronous step-down controller and two positive LDO controllers. The MAX1965T integrates a synchronous step-down controller, three positive LDO controllers, and one negative LDO controller. The MAX1964T output voltages are sequenced, and the MAX1965T output voltages track the rising switch-mode output until individual regulation is achieved at each LDO output.
The current-mode step-down controller uses external N-channel MOSFETs to provide low-cost synchronous rectification for high efficiency and low heat. Its 200kHz switching frequency permits the use of low-cost magnetics and aluminum electrolytic capacitors, while the LDO controllers drive external inexpensive bipolar transistors. To further save cost, no external
current-sense resistor is required. Current-mode control offers good transient response, and an adjustable current limit is provided for protection.
The switch-mode controller input range is 4.5V to 28V to accommodate low-cost, loosely regulated AC adapters. The output is preset to 3.3V or can be adjusted from 1.25V to 20V using a feedback resistor-divider.
The positive linear regulator voltages can be set from 1.25V to 15V, and the negative regulator voltage can be set from -1.25V to -15V, using external feedback resistors. A power-ok (POK) function monitors all outputs, and signals that they are properly regulated.
The MAX1964TEEE comes in a 16-pin QSOP package; prices start at $1.75 (1000-up, FOB USA). The MAX1965TEEP comes in a 20-pin QSOP package; prices start at $2.05 (1000-up, FOB USA). These devices are specified for the extended-industrial temperature range (-40°C to +85°C).
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