LT8705MPFE

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PMIC - Voltage Regulators - DC DC Switching Controllers

LT8705MPFE application field and working principle

The LT8705MPFE is a high-voltage monolithic synchronous buck-boost switching regulator controller. It is designed to operate as a buck, boost, or buck-boost regulator, allowing the output voltage to be set higher or lower than the input voltage, while maintaining reliable, low-noise, efficient operation.

The LT8705MPFE is designed to operate as a constant frequency current mode switching voltage regulator with a maximum output current of 6 A. The current mode architecture includes a high precision, programmable slope compensation network to ensure good loop stability, as well as high-frequency/low-output resistance compensation to minimize inductor size.

The LT8705MPFE features an integrated DC-DC switching controller with a wide range of features including: programmable output voltage, adjustable switching frequency, output voltage buck-boost mode, output voltage adaptive over-current protection. It also features two separate inputs: a power input and a low-voltage reference input.

The LT8705MPFE also features two programmable features: soft-start and power good delay. Soft-start adjusts the slew rate of the voltage ramp when starting up, allowing for a better system performance. The power good delay controls the duration of the power good signal before it deasserts if the voltage regulation loop becomes unstable.

The LT8705MPFE is suitable for a wide range of applications, such as battery powered hand-held equipment, LED driver, home appliance, and more. It is an ideal choice for applications that require a wide input operational range, up to 60V.

Working principle of the LT8705MPFE

The LT8705MPFE utilizes a synchronous rectifier buck-boost topology for drawing energy from the power input and storing it in output capacitors. It uses two internal switches, an internal low-side FET and an internal high-side FET, to convert the power between the input and output of the system. The internal FETs are controlled by an internal driver block through an input voltage sampling network and an output voltage feed-back loop.

The operation of the LT8705MPFE is controlled by an internal PWM controller which adjusts the duty cycle of the internal FETs accordingly to maintain the desired output voltage. The PWM controller has its own internal compensation network to maintain a stable voltage regulation loop. It also features an output voltage adaptive over current protection circuit for preventing damage to the internal FETs.

The LT8705MPFE can operate in a wide input voltage range from 5V to 60V and support output voltage from 3V to 55V, enabling operation in many different applications. The overall efficiency of the LT8705MPFE varies from 82% typical up to 95% depending on the duty cycle requirements and the input and output voltage values.

Conclusion

The LT8705MPFE high-voltage monolithic synchronous buck-boost switching voltage regulator is designed to operate within a wide input operational range up to 60V, while maintaining reliable, low-noise and efficient operation. It also features a programmable soft-start and power good delay, which are key features for many applications. Moreover, with its high efficiency rating and wide output voltage range, the LT8705MPFE is the ideal choice for many applications.

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