Linear Technology has introduced a new dual-output synchronous step-down DC-DC controller with an I²C-based PMBus interface for digital power system management.
This device differs from the previously released LTC3887 in that it provides a tri-state PWM signal so that DrMOS, power blocks or similar power stages can be used. The enhanced function set of LTC3887-1 includes a 70ms power-up time and a fast ADC mode, which provides an update rate of 8ms for a parameter.
The LTC3887-1 regulates two independent outputs or can be configured as a 2-phase single output from 0.5V to 5.5V. Up to 6 phases can be interleaved and paralleled for accurate sharing among multiple ICs, minimizing input and output filtering requirements for high-current or multi-output applications. The integrated amplifier provides true differential remote output voltage sensing for high-precision regulation without being affected by board-level IR voltage drops. Applications include high current ASICs, FPGAs and processor power supplies in the telecommunications, data communications, computing and storage markets.
The LTC3887-1 operates from an input voltage range of 4.5V to 24V, and produces an accurate output voltage of ± 0.50% from 0.5V to 5.5V, and the output current of each phase is as high as 40A over the entire operating temperature range. . The highest efficiency is achieved by sensing the current by sensing the voltage drop across the output inductor (DCR), or an external sense resistor can be selected. Programmable DCR temperature compensation eliminates the temperature coefficient of copper inductors, maintaining accurate and constant current limits over a wide temperature range. Accurate timing and event-based sequencing between multiple chips can optimize power up and power down of complex circuits, and multi-track systems. Other features include constant frequency current mode control with cycle-by-cycle current limit, adjustable soft-start,
The LTC3887-1 combines best-in-class analog switching regulator performance with accurate mixed-signal data conversion, enabling the LTpowerPlay power development system to provide it with unparalleled ease of power system design and management. The LTC3887-1 supports digital programming and readback to control and monitor critical load point converter functions in real time. Programmable control parameters include output voltage, margin and current limits, input and output monitoring limits, power-up sequencing and tracking, switching frequency, and identification and traceability data. On-chip precision data converter and EEPROM allow capture and non-volatile storage of regulator configuration settings and telemetry variables, including input and output voltage and current, duty cycle,
using Linear Technology's LTpowerPlay GUI-based development software, available through The device's I²C serial interface easily saves the configuration of the LTC3887-1 to the internal EEPROM. By storing the configuration on-chip, the controller can automatically power up without burdening the host processor. The default settings can be arbitrarily configured via an external resistor divider to output voltage, switching frequency, phase, and device address. Multiple designs can be easily calibrated and firmware configured to optimize a single hardware design for a variety of applications. After modifying the power supply parameters, the converter loop gain does not change, so compensation remains optimal for multiple configurations.
The LTC3887-1 is available in a 40-pin 6mm x 6mm QFN package and has an operating junction temperature range of -40C to 125C. The company said it can provide custom device configuration programming services.
