Linear introduced a dual channel output synchronous buck DC/DC controller

     Linear introduced the LTC3887, a dual-channel output synchronous step-down DC/DC controller with an I2C-based PMBus interface for digital power system management. The LTC3887 differs from the previously released LTC3880 in that it has an enhanced feature set, including a faster 70ms power-on time, higher output voltage capability, and a fast ADC mode that provides an 8ms update rate for one parameter. In addition, the LTC3887 and LTC3880 have a common board component package. The LTC3887 combines best-in-class analog switching regulator performance with precise mixed-signal data conversion for unmatched ease of power system design and management, supported by the LTPowerPlayTM software development system with an easy-to-use graphical user interface (GUI).

     The LTC3887 implements digital programming and read-back for real-time control and monitoring of critical point-of-load converter functions. Programmable control parameters include output voltage, margin regulation and current limits, input and output monitoring limits, power-on sequencing and tracking, switching frequency, and identification and traceability data. On-chip high-precision data converters and EEPROMs provide capture and non-volatile storage of voltage regulator configuration Settings and telemetry variables, including input and output voltage and current, duty cycle, temperature, and fault logging.

     The LTC3887 can adjust two independent outputs or be configured for two-phase single-channel outputs. Up to 6 phases can be interlaced and shunt to achieve accurate current sharing across multiple ics, minimizing input and output filtering requirements for high-current and/or multi-output applications. An integrated amplifier provides true differential remote output voltage sampling for high accuracy regulation independent of the board IR voltage drop. Its applications include high-current ASics, FPgas, and processor power supplies in the telecommunications, data communications, computing, and memory markets.

     The configuration of the LTC3887 can be easily saved to the internal EEPROM via the device's I2C serial interface using Linear Technology's LTpowerPlay GUI development software. With the on-chip storage configuration, the controller can perform an autonomous power-on without bothering the main processor. Optional default Settings for output voltage, switching frequency, phase, and device address can be configured by an external resistor divider. Multiple designs can be easily calibrated and configured in firmware to optimize a single hardware design for a wide range of applications. The converter loop gain is unchanged when the power parameters are modified, so compensation remains optimized for multiple configurations.

     The LTC3887 features a high-current integrated gate driver to drive a full-n-channel power MOSFET with input voltages ranging from 4.5V to 24V. It is also capable of producing output voltages of 0.5V to 5.5V with an accuracy of ±0.50% and output currents of up to 30A per phase over the entire operating temperature range. Maximum efficiency can be achieved by detecting the current by detecting the voltage drop at both ends of the output inductor (DCR), or alternatively, an external detection resistor can be used. The programmable DCR temperature compensation offsets the temperature coefficient of the copper inductor to maintain accurate and constant current limits over a wide temperature range.

     The device has a minimum on-time of only 90ns, making the LTC3887 ideal for compact HF/high buck ratio applications. Accurate timing and event-based sequencing across multiple chips enables optimization of power and power outages on complex and multi-voltage rail systems. Other features include constant frequency current mode control with cycle by cycle current limitation, adjustable soft start, a synchronizable switching frequency, and programmable GPIO pins to indicate device status and enable autonomous recovery from faults.