Linear Technology Corporation introduces dual output synchronous buck DC/DC controllers

     Linear Technology Corporation introduces the dual output synchronous buck DC/DC controller LTC3887-1 with an I2C-based PMBus interface for digital power system management. Unlike the previously introduced LTC3887, the LTC3887-1 provides a three-state PWM signal, which allows the use of DrMOS, power modules, or similar power level components. The LTC3887-1's enhanced feature set includes a 70ms power-on time and a fast ADC mode that provides an 8ms update rate for one parameter. The LTC3887-1 is available in a 40-pin 6mm x 6mm QFN package with an operating junction temperature range of -40 ºC to 125ºC.

     The LTC3887-1 accommodates two independent outputs and can also be configured for a two-phase single output ranging from 0.5V to 5.5V. Up to 6 phases can be interlaced and paralleled to achieve accurate current sharing across multiple ics, minimizing input and output filtering requirements for high-current or multi-output applications. An integrated amplifier provides true remote differential output voltage detection independent of the board IR voltage drop for high accuracy regulation. Applications include high-current ASics, FPgas, and processor power supplies for the telecommunications, data communications, computing, and storage markets.

     The LTC3887-1 operates over an input voltage range of 4.5V to 24V, producing output voltages of 0.5V to 5.5V with ±0.50% accuracy and output currents of up to 40A per phase over the entire operating temperature range. Maximum efficiency can be achieved by detecting the voltage drop at both ends of the output inductor (DCR) to detect the current, or optionally using an external detection resistor. The programmable DCR temperature compensation eliminates the influence of the temperature coefficient of the copper inductor to maintain accurate and constant current limits over a wide temperature range.

     Accurate timing and event-based power sequencing across multiple chips enables optimization of complex, multi-voltage rail systems for power-on and power-off. Other features include constant frequency current mode control with cycle by cycle current limiting, adjustable soft start, synchronizable switching frequency, and programmable GPIO pins to indicate device status and provide autonomous fault recovery.

     The LTC3887-1 combines best-in-class analog switching regulator performance with high-precision mixed-signal data conversion for unmatched ease of power system design and management, supported by the LTPowerPlayTM power development system with an easy-to-use graphical user interface (GUI). The LTC3887-1 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 setpoints and telemetry variables, including input and output voltage and current, duty cycle, temperature, and fault logging.

     Using Linear Technology LTPowerPlay GUI based development software, the LTC3887-1 configuration can be easily saved to the internal EEPROM via the device's I2C serial interface. Thanks to the configured on-chip storage, the controller can power on its own without bothering the host processor. Default setpoints can be configured selectively by an external resistance divider for output voltage, switching frequency, phase, and device address. Easily calibrate and configure multiple designs with 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.