60V dual DC/DC controller: I²C/PMBus control/analogue loop regulation

August 13, 2015 // By Graham Prophet
LTC3886 is a 60V input dual output synchronous step-down DC/DC controller with programmable loop compensation and I²C-based PMBus interface. This controller employs a constant-frequency, current-mode architecture with programmable output voltage up to 13.8V.

The IC is suitable for harsh environments requiring a high input voltage range, as is commonly found in factory automation, industrial, medical, communications and avionic applications. It can be configured for dual or single output and is stackable up to six phases to support load current up to 120A. Interleaved clock phasing for 2, 3, 4 or 6 phases reduces the input and output ripple, reducing input and output capacitance. This device is supported by the LTpowerPlay software development tool with graphical user interface (GUI). Its serial I²C-based interface enables system designers and remote operators to command and supervise a system’s power condition and consumption. The capability to digitally change power supply parameters reduces time-to-market and down time, eliminating what would typically require physical hardware, circuit or system bill-of-material modifications. The LTC3886 simplifies system characterisation, optimisation and data mining during prototyping, deployment and field operation.

In addition to delivering power to a point-of-load, the LTC3886 features configurability and telemetry monitoring of power and power management parameters over the PMBus (I²C-based) digital serial interface protocol. Its 2-wire serial interface enables outputs to be margined, tuned and ramped up and down at programmable slew rates with sequenced delay times. Input and output voltages, along with input and output currents and temperature are readable. The device comprises fast, dual analogue control loops, precision mixed signal circuitry and EEPROM, and is housed in a 7 x 8 mm QFN-52 package.

To evaluate the performance of the LTC3886, the LTpowerPlay GUI is free for download. USB-to-PMBus converter and demo kits are also available. With ±0.5% maximum DC output error over temperature, ±1.5% current read back accuracy, integrated 16-bit Delta- Sigma ADC and EEPROM, the LTC3886 combines analogue switching regulator performance with precision mixed signal data acquisition. Channels can accurately share current in both steady state and transient conditions. At start-up, output voltages, switching frequency and channel phase angle assignments can be set by pin-strapping resistors or loaded from internal EEPROM. Operating junction temperature range is from -40°C to 125°C: it is priced at $6.35 (1000).

Linear Technology; www.linear.com/product/LTC3886

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