Thanks to the rapid development of switching power supply PSR technology in recent years, the PSR scheme adopts technologies such as multi-working mode + feedforward compensation, and its conversion efficiency, voltage regulation rate, dynamic load response and other indicators have approached or surpassed the SSR scheme. Adapting to the constant current function is beneficial to the reliable operation of the power supply and power supply equipment. Compared with the traditional SSR solution, the optocoupler, 431 and other components can be removed, and the primary auxiliary winding is used as the sampling voltage, which has obvious cost advantages and is favored by the majority of engineers. The following editor will give you an in-depth analysis of the switching power supply primary side feedback (PSR) technology.

One. How is PSR technology generally divided?​​

According to the constant voltage control strategy, we divide the PSR technology into four generations. The first generation works in a single PFM mode and reduces the frequency linearly with the load; The compensation function is rich; the third generation works in the PFM+PWM hybrid mode, and the dynamic and audio noise indicators are greatly improved; the fourth generation works in the CCM+PFM+PW hybrid mode, and the power application level is greatly improved.

Second, the future development direction of switching power supply primary side feedback (PSR) technology?​​

1.In order to achieve higher conversion efficiency and power transmission, the PSR controller needs to operate in more than 3 working modes, and the CCM needs slope compensation. The control objects in different modes vary greatly, and the PSR loop controller needs to choose between stability, accuracy and speed. 

2. In order to achieve lower standby power consumption, the demagnetization time of the transformer is shortened, and the pulse voltage sampling of the PSRcontroller is required to be more accurate to reduce the influence of the leakage inductance oscillation of the transformer on the output voltage estimation.​​

3. It is difficult to improve the constant current accuracy. The high-power PSRcontroller needs to enter the CCM mode. Compared with the previous three generations of DCM constant current, the CCM constant current needs to be sampled at the midpoint of the primary current of the transformer, so as to convert the trapezoidal wave current into a square wave. current, constant current accuracy is affected.

If you want to know more about the primary side feedback (PSR) scheme of switching power supply chip, you can consult ShenZhen Hao Qi Core Technology  online customer service.