8-ch flexible 1A buck DC/DCs promise efficiency, 1% accuracy for multi-rail systems

August 11, 2016 // By Graham Prophet
LTC3374A is a highly integrated general-purpose power management solution for systems requiring multiple low voltage power supplies. The device can be configured to provide two to eight independent regulated outputs with 15 possible output current configurations.

This flexibility suits the LTC3374A, Linear Technology asserts, for a wide variety of multichannel applications, including industrial, automotive and communications systems. The LTC3374A has a peak efficiency of 94%, one output with ±1% voltage accuracy and up to seven additional outputs with ±2% accuracy. A power-good function indicates that the output is in regulation with ±1% accuracy and provides overvoltage indication. A temperature monitor with ±3°C accuracy is also included.

 

The LTC3374A features eight independent 1A channels with flexible sequencing and fault monitoring. Each channel is a high efficiency synchronous step-down regulator with its own independent 2.25V to 5.5V input supply and an output voltage range of 0.8V to VIN. Up to 4 adjacent buck regulators can be combined in parallel to provide up to 4A of output current with a single shared inductor by connecting their VIN pins together, their SW pins together, and by connecting the slave bucks’ FB pin(s) to the input supply. In this way, 15 different output configurations are possible.

 

The LTC3374A’s switching regulators operate in one of two modes: Burst Mode operation (power-up default mode) for higher efficiency at light loads, and forced continuous pulse width modulation (PWM) mode for lower noise at light loads. All of the switching regulators are internally compensated and need only external feedback resistors to set the output voltage. The bucks have input current limiting, soft-start to limit inrush current during start-up, and short-circuit protection. The device has a programmable and synchronizable 1 MHz to 3 MHz oscillator with a 2 MHz default switching frequency. The quiescent current with all DC/DCs off is zero. Other features include a die temperature monitor output (readable via an analogue voltage on the TEMP pin) which indicates internal die temperature, and an over-temperature (OT) function, which disables the bucks at high die temperatures.

 

The LTC3374A is available in a thermally enhanced, low profile (0.75 mm), 38-pin TSSOP and 5 x