Summary of LT8228 – 100 V BIDIRECTIONAL BUCK OR BOOST DC/DC CONTROLLERS WITH PROTECTION
Analog Devices’ LT8228 is a 100 V bidirectional buck/boost DC/DC controller for hybrid and EV non-drive subsystems. It manages 48 V and 12 V batteries with bidirectional power transfer, automatic or external flow-direction control, MOSFET-based input/output protection, independent current limiting and monitoring, masterless fault-tolerant current sharing, and diagnostic pins for FAULT and REPORT. It supports up to 100 V on input/output, offers separate error amplifiers for buck and boost modes, and comes in a 38-lead TSSOP package enabling redundancy and full functional safety if one battery fails.
Parts used in the LT8228 Bidirectional Buck or Boost Controller Project:
- LT8228 100 V bidirectional buck/boost DC/DC controller (38-lead TSSOP)
- Input protection MOSFETs
- Output protection MOSFETs
- Switching MOSFETs
- Adjustable timer circuit breaker
- Error amplifier circuitry (two error amplifiers with separate compensation pins)
- Current sensing components for bidirectional current limiting and monitoring
- FAULT and REPORT diagnostic interface pins
- External control interface for direction of power flow
- Passive components for compensation, filtering, and power stage (resistors, capacitors, inductors)
Analog Devices’ controllers enable full functional safety if one of the batteries fail by forcing the other battery to take over
Analog Devices’ LT8228 100 V bidirectional buck or boost DC/DC controllers provide sustainable power in hybrid and electric vehicle (EV) critical non-drive train subsystems by controlling 48 V and 12 V batteries with bidirectional capabilities allowing for power source redundancy. These controllers also enable full functional safety if one of the batteries fails by forcing the other battery to take over allowing the vehicle to function properly, avoiding potential catastrophic results.
Features
- Automatically determines the direction of power flow or the direction can be externally controlled
- Provides a step-down output voltage when in buck mode or a step-up output voltage when in boost mode
- Input and output voltage can be set as high as 100 V
- Two error amplifiers, one for boost mode and the other for buck mode, with separate compensation pins
- 38-lead TSSOP package
The LT8228 automatically determines the direction of power flow, or the direction can be externally controlled. Input and output protection MOSFETs protect against negative voltages, control inrush currents, and provide isolation between terminals under fault conditions such as shorts in the switching MOSFETs. In step-down mode, protection MOSFETs prevent reverse current. In step-up mode, the same MOSFETs regulate the output inrush current and use an adjustable timer circuit breaker to protect themselves.
Simplified Schematic
The LT8228 implements bidirectional input and output current limiting as well as independent current monitoring. Masterless, fault-tolerant current-sharing allows LT8228 chips to work in parallel and to be added or subtracted while maintaining current sharing accuracy. Internal and external fault diagnostics and reporting are available via separate pins (FAULT and REPORT). Each LT8228 regulates to the average output current, thus eliminating the need for a master controller. When an individual LT8228 is disabled or in a fault condition, it stops contributing to the average bus, making the current sharing scheme fault-tolerant. The LT8228 sits in a 38-lead TSSOP package.
The LT8228 controller provides a step-down output voltage when in buck mode or a step-up output voltage when in boost mode. The input and output voltage can be set as high as 100 V. In applications such as battery backup systems, the bidirectional feature allows the battery to be charged from either a higher or lower voltage supply. When the supply is unavailable, the battery boosts or bucks power back to the supply.
Read more: LT8228 – 100 V BIDIRECTIONAL BUCK OR BOOST DC/DC CONTROLLERS WITH PROTECTION
- What voltages can the LT8228 input and output be set to?
Input and output voltage can be set as high as 100 V according to the article. - Does the LT8228 support bidirectional power flow?
Yes, the LT8228 provides bidirectional buck and boost capability and can automatically determine power flow direction or be externally controlled. - How does the LT8228 handle a battery failure?
The controllers enable full functional safety by forcing the other battery to take over, allowing the vehicle to continue functioning. - Can multiple LT8228 chips share current without a master controller?
Yes, they implement masterless, fault-tolerant current-sharing and regulate to the average output current. - What protection features are provided for MOSFETs?
Input and output protection MOSFETs protect against negative voltages, control inrush currents, provide isolation under faults, prevent reverse current in buck mode, and regulate inrush current with an adjustable timer in boost mode. - Are there diagnostics available on the LT8228?
Yes, internal and external fault diagnostics and reporting are available via separate FAULT and REPORT pins. - Does the LT8228 have separate error amplifiers for buck and boost modes?
Yes, it includes two error amplifiers, one for boost mode and the other for buck mode, each with separate compensation pins. - What package does the LT8228 come in?
The LT8228 is available in a 38-lead TSSOP package.
