Features: Low Total Harmonic Distortion (THD) Dual Output Voltage Control Accurately Adjustable Output Overvoltage Protection Open Feedback Protection and Disable Function Zero Current Detector 160µs Internal Start Timer mosfet Overcurrent Protection Undervoltage Lockout, Hysteresis 3.5V Low Startup (40µA) and Operating Current (1.5mA) Totem Pole Output with High State Clamp ± 400mA Peak Gate Drive Current 8-Pin Dip or 8-Pin SOP

Application: Adapter related application description AN-6012: Power factor correction circuit design using 7528 -ic/" title="FAN7528 product parameters, documentation and supply information" target="_blank">FAN7528

Description: The FAN7528 is an active power factor correction (PFC) boost PFC application controller critical conduction mode (crm). It uses the voltage mode comparison of the internal ramp signal and the error amplifier output to generate the MOSFET turn-off signal. Because the voltage mode CRM PFC controller does not require rectified AC line voltage information, the power consumption of the input voltage sensing network can be saved. Required by the current mode CRM PFC controller of. The FAN 7528 provides dual output voltage control for AC line voltage sensing applications without the use of an adapter. It varies the output voltage of the PFC according to the AC line voltage. Provides protection functions such as overvoltage protection, open feedback protection, overcurrent protection, and undervoltage lockout protection. Fan 7528 If the INV pin voltage is lower than 0.45V, the operating current can be disabled to reduce to 65 microamps. The new variable real-time control method, the THD is lower than the traditional CRM, which promotes the development of PFC integrated circuits.

Application Information: An Error Amplification Module The error amplification module has several functions, such as dual output function, overvoltage protection function, and disable function. 1.1 Dual output function Different from traditional crm pfc controller, fan7528 has dual output control function of line voltage, no need to sense and rectify AC line voltage. Because the output voltage of the boost converter is proportional to the peak voltage of the input AC line voltage before the boost converter starts switching, the INV pin voltage represents the peak voltage of the AC line. When the AC line is connected to the boost converter, the VCC voltage increases from zero voltage. If the VCC voltage reaches 8.5V, the dual output reference generator compares the INV pin voltage with the 1.3V reference voltage, and if the INV pin voltage is lower than 1.3V, Dual Output Reference Genset Reference Voltage Error If the INV pin voltage is higher than 1.3V, the reference voltage is set to 2.5V. This means that if the output voltage of the boost converter is on the high line, the output voltage is 240V (400V*1.5/2.5) on the low line. If the output voltage on the high line is set to 390V, the low line output voltage is 234V because this block does not require input voltage sensing The power loss and cost associated with the sensor network can be saved until VCC falls below 4.5V and the reference voltage of the error amplifier does not reset.

1.2 Over-voltage protection function The control speed of the PFC converter is very slow; therefore, the over-voltage protection of the output voltage is very important. FAN7528 provides an accurate OVP function to shut down the drive circuit. When the INV pin voltage exceeds 2.66V, the 0.11V lag. 1.3 Disable function If the INV pin voltage is lower than 0.45V, the internal block is disabled, the operating current is reduced to 65µA, and the comparator is switched on. 1.4 Error amplifier The error amplifier is a transconductance amplifier. The output current of the amplifier with the inverting input and the non-inverting input of the amplifier some resistors and capacitors should be connected to the output pin of the error amplifier output voltage loop, the COMP pin to compensate. 2 Zero Current Detection Block The Zero Current Detector (ZCD) generates the boost inductor current when the signal from the mosfet is coupled to the zero inductor using the auxiliary winding If the voltage at the ZCD pin is above 1.5V, the ZCD comparator waits for the voltage to disappear below 1.4V . If the voltage is below 1.4V, the zero current detector will turn on the MOSFET ZCD pin is generated by two 6.7V high clamp and 0.6V low clamp 160µs timer MOSFET if the driver output is too low for more than 160µs from the falling edge of the driver output above.

3. The sawtooth generator set the output of the error amplifier and compared to the sawtooth generator to determine the slope of the sawtooth for the instance in which the MOSFET is turned off by connecting it to the Moto pin. The motor pin voltage is 1V and the slope is proportional to the current flowing from the MOT pin. The internal ramp signal has a 1V offset; so if the voltage at the compressor pin is below 1V, the MOSFET is on for maximum time. When the COMP pin voltage is 5V. The maximum on-time can be programmed according to the internal slope of the slope. The necessary maximum on-time depends on the boost inductor, the minimum AC line voltage and the maximum output power. The resistor value should be designed.

4. The overcurrent protection block uses an external sense resistor to sense the MOSFET current for overcurrent protection. If the CS pin voltage is higher than 0.8V, the overcurrent protection comparator generates a protection signal. The internal RC filter is used to filter out of switching noise.

5. The switch driver block FAN7528 contains a totem pole output stage designed as a direct drive driver for power MOSFETs. Under 1nF load, the output is capable of reaching a peak current of 400mA with a typical rise and fall time of 50ns. The output is designed to protect the MOSFET gate, the voltage is clamped to 13V even if the VCC voltage is higher than 13V. 6 Under-voltage lockout If the VCC voltage reaches 12V, the IC's internal modules are enabled and begin to operate. If the VCC voltage drops below 8.5V, most of the internal modules are disabled to reduce operating current. The VCC voltage should be higher than 8.5V under normal conditions.

Features: High Efficiency (>90% at 90VAC Input) Low THD (Total Harmonic Distortion) (<10% at 264VAC Input) Dual Output Control Key Design Notes Diode D4 is used to prevent CS pin voltage from falling below -0.3 IC failure that can occur at V. Important components for low THD are R2, R5 and C11.