FAN5110MX Integrated Circuits (ICs)

FAN5110MX Application Field and Working Principle

FAN5110MX is a single-phase bridge gate driver from Fairchild Semiconductor which uses synchronous rectification technology and is applicable in variety of applications within the field of power management. This device is used for driving the step-down DC/DC synchronous rectifier for regulating its output voltage, to increase its efficiency and robustness. It also has applications in boost converters.

Features

• Max switching frequency of 1.5 MHz
• Output current up to 3 A
• Meets the requirements of 500 V creepage distance
• Under-voltage lockout protection with hysteresis
• Over-temperature protection
• Over-current protection
• Soft start
• Overtemperature and overvoltage protection
• Output slew rate control
• Low power standby mode

Applications

• DC/DC non-isolated synchronous rectification forward converters
• High-efficiency DC/DC boost converters
• LED driving
• Heaters
• Home electronics
• Battery chargers
• Power supply
• Battery management

Working Principle

FAN5110MX has an integrated power MOSFET gate driver and an adjustable-threshold under-voltage lockout (UVLO) circuit that allow it to drive one high-side and one low-side MOSFET in synchronous rectification configurations. The low-side switch is driven by an internal low-side driver and the high-side switch is driven by a separate high-side driver, both with a 3 A sink/source current capability. The UVLO circuit monitors the voltage of the DC bus voltage and controls the gate drive signals for the high-side and low-side MOSFETs. When the UVLO voltage level is reached, the gate drive signals are inhibited and the MOSFETs are electronically turned off. The output current is limited to 3 A.

When the MOSFETs are switched off, FAN5110MX enters a low-power standby mode, in which the current drawn is less than 10 uA. This low-power standby mode ensures that the device energy consumption is kept to a minimum when the system is not in use. The slew rate control of the outputs limits the rate-of-change of the gate voltage to prevent the occurrence of conducting shoot-through currents, which would reduce the efficiency of the synchronous rectification converter.

FAN5110MX includes an overcurrent protection circuit, which limits the output current when the current reaches the upper limit set by the resistors connected to the CS pins of the IC. The overcurrent protection circuit is also capable of limiting the currents in both the high-side and the low-side MOSFETs.

FAN5110MX also includes an over-temperature protection circuit, which monitors the internal temperature of the device and limits the output current when the temperature reaches the upper limit set by the resistors connected to the CS pins of the IC. In addition, FAN5110MX has a soft start circuit which reduces the maximum gate drive current at startup to reduce inrush currents. The soft start circuit is also able to reduce the operating frequency of the converter while the voltages ramp up.