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Synchronous stepdown DC/DC controller touts precise conversion

Posted: 31 Jan 2011 ?? ?Print Version ?Bookmark and Share

Keywords:DC/DC controller? digital? power system management? I<SUP>2</SUP>C?

Linear Technology Corp. debuts the LTC3880/-1a dual output high efficiency synchronous step-down DC/DC controller with I2C-based PMBus interface for digital power system management. The device claims best in class analog switching regulator performance with precision mixed signal data conversion, supported by the LTpowerPlay software development system with an easy-to-use GUI.

The controller allows for digital programming and read back for real-time control and monitoring of critical point-of-load converter functions. Programmable control parameters include output voltage, margining and current limits, input and output supervisory limits, power-up sequencing and tracking, switching frequency and identification and traceability data. On-chip precision data converters and EEPROM allow for the capture and nonvolatile storage of regulator configuration settings and telemetry variables, including input and output voltages and currents, duty cycle, temperature and fault logging.

The device can regulate two independent outputs or be configured for a two phase single output. Up to six phases can be interleaved and paralleled for accurate sharing among multiple ICs, minimizing input and output filtering requirements for high current and/or multiple output applications. An integrated amplifier provides true differential remote output voltage sensing, enabling high accuracy regulation, independent of board IR voltage drops. Applications include high current ASIC, FPGA and processor supplies in telecom, datacom, computing and storage markets.

Configurations for the LTC3880/-1 can be saved to internal EEPROM over the device's I2C serial interface using Linear Technology's LTpowerPlay GUI-based development software. With configurations stored on-chip, the controller can power up autonomously without burdening the host processor. Default settings can be optionally configured by external resistor dividers for output voltage, switching frequency, phase and device address. Multiple designs can be easily calibrated and configured in firmware to optimize a single hardware design for a range of applications. The converter loop gain does not change as the power supply parameters are modified, so compensation remains optimized for multiple configurations.

The LTC3880 features high current integrated gate drivers to drive all N-channel power MOSFETs from input voltages ranging from 4.5V to 24 V, and it can produce ?0.50 percent accurate output voltages from 0.5V to 5.5V with output currents up to 30 A per phase over the full operating temperature range. Highest efficiency is achieved by sensing the voltage drop across the output inductor (DCR) to sense current, or an external sense resistor can optionally be used. Programmable DCR temperature compensation cancels the TC of the copper inductor to maintain an accurate and constant current limit over a broad temperature range.

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