ld7575b Leadtrend Technology, ld7575b Datasheet - Page 12

• Manufacturer Part Number: ld7575b
• Description: Green-mode Pwm Controller With High-voltage Start-up Circuit
• Manufacturer: Leadtrend Technology

Protection Resistor on the Hi-V Path
In some other Hi-V process and design, there may cause a
parasitic SCR between HV pin, Vcc and GND. As shown
Leadtrend Technology Corporation
LD7575B-DS-00 May 2008
Fig. 19
Fig. 20
i
=
Cgd
⋅
dV
dt
bulk
12
in figure 21, a small negative spike on the HV pin may
trigger this parasitic SCR and causes the latchup between
Vcc and GND. And such latchup is easy to damage the
chip because of the equivalent short-circuit which is induced
by such latchup behavior.
Thanks to the Leadtrend’s proprietary Hi-V technology,
there is no such parasitic SCR in LD7575B.
shows the equivalent circuit of LD7575B’s Hi-V structure.
So that LD7575B is with higher capability to sustain
negative voltage than similar products. However, a 40KΩ
resistor is recommended to implement on the Hi-V path to
be played the role as a current limit resistor whenever a
negative voltage is applied in any case.
Fig. 21
Fig. 22
LD7575B
Figure 22