太离谱了求救

满江红

pxh1982 发表于 2026-1-13 21:04
7脚启动电阻不良

7脚不是启动端，是欠压保护，当电压低于1.25V时，电源保护。

datasheet  有关7脚的功能描述如下：

Line sensing input. The pin is to be connected to the high-voltage input bus with a resistor
divider to perform either AC or DC (in systems with PFC) brownout protection. A voltage
below 1.25 V shuts down (not latched) the IC, lowers its consumption and discharges the
soft-start capacitor. IC’s operation is re-enabled (soft-started) as the voltage exceeds 1.25 V.
The comparator is provided with current hysteresis: an internal 15 µA current generator is
ON as long as the voltage applied at the pin is below 1.25 V and is OFF if this value is
exceeded. Bypass the pin with a capacitor to GND to reduce noise pick-up. The voltage on
the pin is top-limited by an internal zener. Activating the zener causes the IC to shut down
(not latched). Bias the pin between 1.25 and 6 V if the function is not used.

满江红

1脚为软启动端，正常和故障时电压分别是多少V?