Dual-output DC/DC controller: digital interface, 0.25 mΩ sense resistance

August 15, 2014 // By Graham Prophet
LTC3882 is a dual output multiphase synchronous step-down DC/DC controller with a serial digital interface. It employs leading-edge modulation voltage-mode control for excellent transient response and operates with very low DCR (0.25 milliohm) inductors, enabling higher efficiency and up to 40A per output phase.

Compatible power train devices include DrMOS, power blocks or discrete FET drivers and associated N-channel MOSFETs.

In addition to delivering power to a point-of-load, the LTC3882 features configurability and telemetry-monitoring of power and power management parameters over PMBus - the open standard I²C-based digital serial interface protocol. A 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 and output currents, output power, temperature and peak values are readable. The device comprises fast, dual analogue control loops, precision mixed-signal circuitry, EEPROM and is housed in a 6mm x 6mm QFN-40 package.

The digital interface enables system designers and remote operators to command and supervise a system's power condition and consumption. The LTC3882 simplifies system characterisation, optimisation and data mining during prototyping, deployment and field operation. Applications include optical transport systems, datacom and telecom switches and routers, industrial test equipment, robotics, RAID and enterprise systems, where the cost of electrical utilities, cooling and maintenance are critical.

To evaluate the performance of the LTC3882, the LTpowerPlay GUI (graphic user interface) is free for download. USB-to-PMBus converter and demo kits are also available. With ±0.5% maximum DC output error over temperature, ±1% current read back accuracy, integrated 16-bit Delta Sigma ADC and EEPROM, the LTC3882 combines analogue switching regulator performance with precision mixed signal data acquisition. It operates from an IC power supply between 3V and 13.2V and is intended for conversion from VIN between 3V and 38V to output voltages between 0.5V and 5.25V. Channels can accurately share current in both steady state and transient conditions. Up to four LTC3882s can operate in parallel for 2-, 3-, 4-, 6- or 8-phase operation. At start-up, output voltages, switching frequency and channel phase angle assignments can be set by pin-strapping resistors or loaded from internal EEPROM. The LTC3882 internal operating temperature range is from -40°C to 125°C. Price