Summary of Convert any input voltage from 2.8V to 80V into a fixed output voltage or output current
The LT8705 is a high-efficiency synchronous buck-boost DC/DC controller by Linear Technology Corporation, supporting input voltages from 2.8V to 80V and delivering up to 250W of output power. It features four feedback loops for precise regulation of input/output current and voltage, making it ideal for solar, automotive, and telecom applications. The device uses a single inductor with 4-switch synchronous rectification and offers selectable operating frequencies.
Parts used in the LT8705 Project:
- Synchronous buck-boost DC/DC controller (LT8705)
- Single inductor
- Quad N-channel MOSFETs
- Onboard gate drivers
- 3.3V/12mA LDO
- Die temperature monitor
- External clock source (for synchronization)
- Servo pins
Linear Technology Corporation announced the LT8705, a very high efficiency (up to 98%) synchronous buck-boost DC/DC controller that operates from input voltages above, below or equal to the regulated output voltage. This device has four feedback loops to regulate the input current/voltage, along with the output current/voltage.
The input current and voltage feedback loops can prevent overloading of solar cells. The output current loop provides a regulated output current for a battery charger or current source. The LT8705 can be used in a wide range of applications such as a voltage stabilizer in telecom and automotive requirements, as well as in solar or high impedance sources and battery systems.
The LT8705 operates over a wide 2.8V to 80V input voltage range and produces a 1.3V to 80V output, using a single inductor with 4-switch synchronous rectification. Output power up to 250W can be delivered with a single device. Higher output power can be achieved when multiple circuits are paralleled. The operating frequency is selectable between 100kHz and 400kHz, and can be synchronized to an external clock.
The LT8705 employs a proprietary current-mode control architecture for constant frequency operation in buck or boost mode and has powerful onboard quad N-channel MOSFET gate drivers. The user can select among forced continuous, discontinuous and Burst Mode® operation to maximize light load efficiency.
Additional features include servo pins to indicate which feedback loops are active, a 3.3V/12mA LDO, adjustable soft-start, onboard die temperature monitor and ±1% reference voltage accuracy over an operating junction temperature range of -40°C to 125°C.
For more detail: Convert any input voltage from 2.8V to 80V into a fixed output voltage or output current
- What is the primary function of the LT8705?
The LT8705 is a very high efficiency synchronous buck-boost DC/DC controller that regulates input and output current/voltage. - Can the LT8705 operate when input voltage is below or above the output voltage?
Yes, the device operates from input voltages above, below, or equal to the regulated output voltage. - How does the LT8705 prevent overloading of solar cells?
The input current and voltage feedback loops are designed to prevent overloading of solar cells. - What is the maximum output power delivered by a single LT8705 device?
Output power up to 250W can be delivered with a single device. - How is the operating frequency determined for the LT8705?
The operating frequency is selectable between 100kHz and 400kHz and can be synchronized to an external clock. - What modes of operation are available to maximize light load efficiency?
Users can select among forced continuous, discontinuous, and Burst Mode operation. - Does the LT8705 include onboard temperature monitoring?
Yes, the device includes an onboard die temperature monitor. - What is the reference voltage accuracy of the LT8705 over its temperature range?
The device provides ±1% reference voltage accuracy over an operating junction temperature range of -40°C to 125°C.
