LT8584 Monolithic Flyback DC/DC Converter

By Analog Devices Inc 36

LT8584 Monolithic Flyback DC/DC Converter

Linear Technology's LT8584 is a monolithic flyback DC/DC converter designed to actively balance high-voltage stacks of batteries. The high efficiency of a switching regulator significantly increases the achievable balancing current while reducing heat generation. Active balancing also allows for capacity recovery in stacks of mismatched batteries. In a typical system, greater than 99% of the total battery capacity can be recovered. The LT8584 includes an integrated 6 A/50 V power switch, reducing the complexity of the application circuit. The device runs completely off of the cell which it is discharging, eliminating the complicated biasing schemes. The LT8584 provides system telemetry including current, temperature, and impedance monitoring when used with the LTC680x family of battery monitors. Here are the device’s development motivations:

  • Big batteries are expensive - they all degrade over time and lose capacity
  • Low cost / refurbished cells have greater capacity mismatch
  • Increasing stack capacity with mismatched cells done in two ways:
    • Use bigger batteries
    • Use active balancing
  • Active balancing maximizes run time and allows fastest charge rates
  • LT8584 offers:
    • Highest energy recovery (max. run time)
    • Fastest balancing time (min. charge time)
    • Numerous safety features
  • 2.5 A typical average cell discharge current
  • Integrated 6 A, 50 V power switch
  • Integrates seamlessly with LTC680x family: no additional software required
  • Selectable current and temperature monitors
  • Ultralow quiescent current in shutdown
  • Engineered for ISO 26262 compliant systems
  • FMEA compatible
  • Isolated balancing:
  • Can return charge to top of stack
  • Can return charge to any combination of cells in stack
  • Can return charge to 12 V battery for alternator replacement
  • Can be paralleled for greater discharge capability
  • All quiescent current in operation taken from local cell
  • 16-lead TSSOP package