8-Channel Configurable 1A Step-Down DC/DC Regulator for Multi-Power Rail Systems

 Linear Technology Corporation introduces the LTC3375, a highly integrated universal power management solution for systems requiring multiple low voltage supplies. The LTC3375 features eight independent 1A channels, I2C ^control , flexible sequencing and fault monitoring in a compact QFN package. The LTC3375 includes eight internally compensated high efficiency synchronous buck regulators and a high voltage and always-on 25mA LDO controller. Each buck regulator has its own independent 2.25V to 5.5V input supply and an output voltage range of 0.425V to VIN _. The device's push button ON/OFF/RESET control, power-on reset and watchdog timer provide flexible and reliable power-up sequencing and system monitoring. The LTC3375 features a programmable and synchronizable 1MHz to 3MHz oscillator and a 2MHz default switching frequency. With all DC/DCs off, quiescent current is only 11µA, extending battery run time. The device is ideal for a wide variety of multichannel applications including industrial, automotive, and communications systems.

The LTC3375's step-down DC/DC regulators can be used independently or connected in parallel to achieve higher output currents of up to 4A per output with a single shared inductor. Up to four adjacent regulators can be combined, resulting in 15 different output configurations. Adjacent buck regulators can be combined in a master-slave configuration by connecting the V _IN and SW pins of the adjacent buck regulators together and connecting the FB pin of the slave buck regulator to the input supply. All switching regulators are internally compensated and require only external feedback resistors to set the output voltage. Alternatively, the output voltage can be set via I ² C. These switching regulators offer two operating modes: Burst Mode ^® operation (power-on default mode) for higher efficiency at light loads and forced continuous PWM mode for lower noise at light loads. The ^{I 2} C interface can be used to select the operating mode, phase, feedback regulation voltage and switching slew rate. These step-down regulators feature forward and reverse current limiting, soft-start to limit inrush current at startup, short-circuit protection, and slew rate control for lower EMI emissions. Other features include a die temperature monitor output that indicates the internal die temperature (readable via I2C ⁾ and an over-temperature (OT) alarm function that warns the user that the die temperature is approaching the OT threshold.

The LTC3375 is available from stock in a thermally enhanced, low profile (0.75mm), 48-lead 7mm x 7mm exposed pad QFN package. The E- and I-grade versions are specified over the -40°C to + 150°C  temperature range. The E-grade is priced at $5.45 each in 1,000-piece quantities. For more information, visit www.linear.com/product/LTC3375.

Features Summary : LTC3375

8-channel independent step-down DC/DC regulators that can be configured in master-slave mode with a single inductor to achieve up to 4A per output rail

Independent V _IN supply (2.25V to 5.5V) for each DC/DC regulator

All DC/DC regulators have an output voltage range of 0.425V to V _IN

Precision enable pin threshold for autonomous sequencing (or I ² C control)

1MHz to 3MHz programmable/synchronizable oscillator frequency (default is 2MHz)

Phase selectable per channel via I ² C (90° steps)

Programmable power-on reset/watchdog/button timing

Chip temperature monitor output

48-lead 7mm x 7mm QFN package