LTC7871

Demonstration circuit DC2886A is a high power, high efficiency six-phase bidirectional converter featuring the LTC7871 and LTC7060. The terminals labeled V_HIGH and V_LOW are either inputs or outputs depending on the direction of power flow. When the switch at SW1 is in the BUCK position, V_LOW provides a 14V output and V_HIGH is the input with a range of 30V to 70V. When the switch is in the BOOST position, V_HIGH provides a 48V output and V_LOW is the input with a range of 10V to 14V. The maximum V_LOW current is 180A in both directions. The maximum output power is 2.5kW when operating as a buck within the input voltage range. When operating as a boost, the maximum output power is 2.4kW when the input voltage is 14V. External airflow is required when operating at maximum power. The MOSFETs in each phase are driven by the LTC7060 half bridge driver. Each LTC7060 gate driver is placed next to the MOSFETs and receives a PWM signal from the LTC7871.

The inductor current for each phase is sensed with a low 1mΩ sense resistor using a highly accurate AC/DC current sensing architecture with low power dissipation. The LTC7871’s constant-current loop provides a DC current limit for the current flowing in or out of the V_LOW terminal depending on the state of the BUCK pin. This current can be programmed with the SETCUR pin and monitored with the IMON pin.

The DC2886A provides a SPI compatible serial port. With a DC2026C (Linduino^® One) demo board and QuikEval^™ software on a host computer, the user can:

• Margin the regulated V_LOW or V_HIGH up or down.
• Margin the DC current limit up or down with the SETCUR pin.
• Adjust the frequency spread and modulation rate of the spread spectrum circuit, when spread spectrum is enabled.
• Monitor the operational status and faults of the LTC7871.

Additional features of the DC2886A include:

• Pin selectable light load operating modes
  • Buck: FCM, pulse-skipping and Burst Mode^® Operation
  • Boost: FCM and pulse-skipping
• SYNC and CLKOUT pins
• Optional jumper to enable spread spectrum modulation
• RUN, FAULT, PGOOD and PWNEN pins
• BUCK pin to externally control the direction of power flow
• Footprint for an optional heatsink

The EVAL-LT8419-BZ is a high-power, high-efficiency, six-phase bidirectional converter featuring the LTC7871 controller and LT8419 GaN drivers. Each phase uses an LT8419 half-bridge driver to drive EPC2361 GaN FETs, with the gate driver placed close to the FETs and driven by PWM signals from the LTC7871. The VHIGH and VLOW terminals serve as either inputs or outputs, depending on the direction of power flow. In buck mode, which is selected by SW1, the board converts 30V to 70V at VHIGH to a regulated 12V output at V_LOW. In boost mode, it converts 10V to 14V at V_LOW to a regulated 48V output at V_HIGH.

The maximum V_LOW current is 200A in either direction, limited by the selected inductors. Maximum output power is 2.4kW in buck mode across the specified input range, and 2.4kW in boost mode when V_LOW is 12V. External airflow is required for operation at maximum power.

Inductor current in each phase is sensed through a low 1mΩ resistor using a highly accurate AC/DC current-sensing architecture with low power dissipation. The LTC7871 constant-current loop provides DC current limiting for current flowing into or out of the VLOW terminal, depending on the state of the BUCK pin. This current limit is programmable through the SETCUR pin and can be monitored at the IMON pin.

The EVAL-LT8419-BZ includes a SPI-compatible serial port. With a DC2026C (Linduino^® One) demo board and QuikEval™ software on a host computer, the user can:

• Margin the regulated V_LOW or V_HIGH up or down.
• Margin the DC current limit up or down with the SETCUR pin.
• Adjust the frequency spread and modulation rate of the spread spectrum circuit when spread spectrum is enabled.
• Monitor the operational status and faults of the LTC7871.