Internal structure and working principle diagram of HL402

Working Principle The HL402 principle block diagram is shown in Figure 12-47. In the figure, VL is
an optocoupler with electrostatic shielding, which is used to isolate the input signal. Because it
has electrostatic shielding, the HL402's ability to resist common-mode interference is significantly improved. V in the picture.
is a pulse amplifier, transistors V3, V. To realize driving pulse power amplification, V; is a reduction
gate voltage comparator . Under normal circumstances, since the IGBT collector voltage VCE input by pin 9
is not higher than the reference voltage V REF of V;, V; does not flip, and the transistor V; does not conduct pass, so
the drive pulse signal input from pins 17 and 16 is not blocked after being shaped by V, and the drive pulse is
passed through V,, V. After amplification, it is provided to the driven IGBT to drive the IGBT to turn on or off.
Once the driven IGBT is desaturated, the collector voltage sampling signal
VCE input by pin 9 is higher than V. The reference voltage V...comparator V. flipped, the output is high, making the transistor
V. When it is turned on, the voltage regulator tube VDz will drive the output gate voltage Vfi. Reduce to
10V. At this time, the soft-off timer v is reducing the gate voltage comparator V. After the flip reaches the set
time, the positive voltage is output to turn on the transistor V, and the gate voltage is softly turned off to reduce the gate -
emitter threshold voltage of the 1GBT , providing a negative driving voltage to the driven IGBI . Ensure that the driven IGBT is turned off reliably.