ld7578 Leadtrend Technology, ld7578 Datasheet - Page 14

• Manufacturer Part Number: ld7578
• Description: Green-mode Pwm Controller With Hv Start-up Circuit And Otp Protection
• Manufacturer: Leadtrend Technology

Protection Resistor on the Hi-V Path
In some other Hi-V processes and designs, there is
probably some parasitic SCR caused around HV pin, V
and GND. As shown in figure 23, a small negative spike
in the HV pin may trigger this parasitic SCR and cause the
latchup between V
damage the chip easily because of the equivalent
short-circuit induced.
The LD7578 has eliminated the parasitic SCR efficiently.
Figure 24 shows the equivalent circuit of the LD7578’s
Hi-V structure, illustrating that the LD7578 is capable to
Leadtrend Technology Corporation
LD7578-DS-00 October 2008
CC
and GND.
Fig. 21
i
=
Cgd
⋅
dV
Such latchup will
www.leadtrend.com.tw
dt
bulk
CC
14
sustain negative voltage and superior than similar
products. Even though,
recommended to be placed on the Hi-V path.
Fig. 22
Fig. 23
a 40KΩ resistor is still
LD7578