DC/DC controller features a 70ms power-up time

The device combines outstanding analogue switching regulator performance with precision mixed signal data conversion for ease of power system design and management, supported by the LTpowerPlay software development system with easy-to-use GUI.

The controller enables digital programming and read back for real-time control and monitoring of critical POL 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 LTC3887 can regulate two independent outputs or can be configured for a two phase single output. Up to six phases can be interleaved and parallelled for accurate sharing among multiple ICs, minimising 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 telecomms, datacomms, computing and storage markets.

Configurations for the controller are easily 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 device 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 optimise 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 optimised for multiple configurations.

The LTC3887 features high current integrated gate drivers to drive all N-channel power MOSFETs from input voltages ranging from 4.5 to 24V, and it can produce ± 0.50% accurate output voltages from 0.5 to 5.5V with output currents up to 30A per phase over the full operating temperature range. High 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 temperature coefficient of the copper inductor to maintain an accurate and constant current limit over a broad temperature range.

The controller’s minimum on-time of just 90nsec make it suitable for compact high frequency/high step-down ratio applications. Accurate timing across multiple chips and event-based sequencing allow the optimisation of power-up and power-down of complex, multiple rail systems. Additional features include constant frequency current mode control with cycle-by-cycle current limit, adjustable soft start, a synchronisable switching frequency, and programmable GPIO pins to indicate part status and to provide autonomous recovery from faults.

The LTC3887 is available now in a 40-pin 6x6mm QFN package with an operating junction temperature range of -40 to 125°C. The 1,000-piece price starts at $5.47 each.