In essence, the circuit person adds the offset of the connection time of the power switch. The voltage of the line voltage is over zero. When the transient line voltage increases, the offset decreases, so when the line voltage moves to the top of the sine curve, it can be ignored. In addition, the offset is the voltage modulation on the VFF pin (see the ""voltage feed"" section), so that the offset at the low line is very small. And the greater the offset of the high -voltage line with a difference in energy transmission. The effect of the circuit is shown in Figure 39, and the key waveform of the standard TM compares the PFC controller with the chip. In order to maximize the use of THD to optimize circuits, high -frequency filter capacitors should be reduced as much as possible after rectification bridges, compatible with the needs of EMI filtering. In a large, the capacitance itself introduces the conduction dead end of AC input current-even through the PFC pre-regulator to realize the ideal energy transfer, it also reduces the efficiency optimizer circuit.

Tracking enhancement function

In some applications, the output voltage of the PFC pre -regulator may be favorable, so that it can track the RMS input voltage instead Instrument. This is usually called ""tracking promotion"" or ""follower promotion"" method. For L6563s, this can be achieved and ground by connecting resistors (RT) between TBO pins. The DC level of the TBO pin is equivalent to the peak of the multi -pin voltage and the validity voltage of the power supply. The resistor defines a current, which is equal to V (TBO)/RT, that is, input from the pins of L6563s (#1) for internal 1: 1 mirror and depression error placed. In this way, when the power supply voltage increases, the voltage on the TBO pins will also increase the current TBO and GND that flows between the resistors. A larger current will be forced to improve the sinking INV pins and output voltage PFC pre -rositors. Obviously, the output voltage will be opposite if the input voltage is reduced. In order to avoid rising output voltage, if the power supply voltage exceeds the maximum value specified value, the voltage at the TBO pin is shown to 3V. By the correct selection of the bias of the ingel-can be set to the maximum input voltage tracking of the input to the output, the output voltage is kept constant. If you do not use this function, leave your pin: The device will adjust a fixed output voltage.

Starting from the following data:

vin1 u003d minimum input RMS voltage

vin2 u003d maximum input RMS voltage

vo1 u003d adjustment output voltage @vin u003d Vin1

vo2 u003d adjustment output voltage@vin u003d vin2

vox u003d the absolute maximum limit of the adjustment output voltage

Use the following design program to set the output voltage to the required required required required Value:

1. Determine the input of VO u003d VOXRMS voltage vinclamp:

and select a value vinx to make vin2≤vinx lt; vinclamp. This will cause the restricted output voltage range to be lower than VOX (if vinx u003d vinclamp, it is equal to VOX)

2. Determine multiple needles (#3) bias frequency division ratio:

[

[

3. Determine R1, the upper resistance of the output compressor, such as 3 MΩ.

4. Calculate the lower resistor R2 and adjust the resistor RT:

The saturation detection of the inductors

The hard saturation of the voltage sensor may be the fatal event of the PFC pre -regulator : The current rising slope becomes very large (50-100 times steady, see Figure 42), and the delay current in the process of current may reach an abnormally high value. The abnormal current caused by the voltage decrease to reduce the grid to the source voltage through the abnormal current on the sensor, so that the MOSFET may work in the active area, and consumes a lot of power after several switching cycles lead to disaster failure. However, in some applications, such as the AC-DC adapter, in order to save energy, even a well-designed boost electromotor can be turned off. When the PFC stage is re-started due to a large load, the PFC level is restarted due to a large load. Occasionally, mild saturation needs occur. When restarting at a disadvantaged line voltage phase, that is. When the output voltage is significantly lower than the rectifier peak voltage. Therefore, the wave current of the voltage sensor comes from the bridge rectifier, the current is added to the switch, and there is almost no or no voltage used for demagical. In order to process saturated inductors, L6563S is in the current quotation (CS, pin 4). If the voltage is usually limited to 1.1V, stop IC and exceed 1.7 V. After that, the IC will try to restart the circuit of the internal startup; the repetitive time of the starter is twice the nominal value to ensure the inductance and boosting diode. Therefore, the security of the system will be greatly improved.

Power Management/Internal Affairs Management Function

One feature of the integrated circuit is that it is easy Circuit working in the converter. The function of the implementation of the interior management circuit ensures that the transients such as power -powered or power -off or any power -level failure are properly handled. This device provides some pins to achieve this. The PWM controller of the IC and Class Union DC-DC converter is the PIN PWM memory (Figure 44B), when the PFC works normallyAt that time, it is frequent (high impedance). If it works normally, it will turn higher and lose control of the output voltage of the audio interface module (because the feedback loop is disconnected) to turn off the PWM controller of the Lianlian DC-DC converter (See the ""feedback fault protection"" section for more details). The second communication line can be included in the PFC_OK pin (more detailed information, please refer to the ""feedback fault protection"" part). Usually this line is used to allow the PWM controller to allow the PTC converter to run L6563s in an emergency mode to minimize the air load input consumption. Similar interface circuits are shown in Figure 43.

The third communication line is the pin PWM stop (#9), it is operating (#10). The role of the PWM U STOP script is to inhibit the PWM activity PFC-level and class DC-DC converter of these two modules. The pins are usually the road set. If the device is disabled by voltage below 0.8 volt, it will turn lower. What it needs to point out is that the function of the main circuit and the class connected DC-DC converter in the system where the function is located in the system where the PFC phase is located is the first start of the PFC stage to power the two controller and enable the two controller to power and enable it /Disable the operation of DC-DC. It can be used for starting and stopping of the main converter. The easiest case is to enable/disable the PWM controller to connect pwm_stop to an error amplifier (Figure 44A).

If the chip is equipped with a soft starting pin, it can delay the start-up phase of the DC-DC relative to the PFC phase, which is usually required, as shown in Figure 45. In order to make it work normally, a basic assumption is that the threshold of the UVLOPWM controller must be higher than the L6563s threshold.

If it is not, or it is impossible to achieve sufficiently long start latency (because this will prevent the DC-DC level from starting correctly), or simply speaking, the PWM controller is the controller is the PWM controller. Because there is no soft start, the layout of FIG. 46 allows the voltage generated by the DC-DC converter in the PFC level to reach the preset value. Technology depends on the UVLO threshold of the PWM controller.

Another possible use operation and pulse width modulation stop pins (similar, in the system, PFC stage) is a power outage protection, thank you for providing lag. Power -off protection is basically an unlocked device shutdown function, which is activated when the power supply is not voltage. This situation may lead to overheating due to excessive effective value. Powerout also causes the PFC pre -regulator to open the loop, which may cause danger to the PFC phase itself and downstream transformers. If the input voltage suddenly returns to its rated value. Another problem is that in the inverter's power off and this, the output voltage of the converter will not decay to zero monotony. For these reasons, usually the most at the time of power outageTurn off the unit.As shown in Figure 47, IC power off can be easily realized.The plan on the left is universal, and the one on the right can be used on the bias level of the multiplier. The RFF · CFF time constant and the prescribed power -off level and the specified retention time.In the latest case, a resistor does not need a capacitor.The summary of all working conditions in Table 1 can cause the device to stop working.