LD7577

14

Leadtrend Technology Corporation

www.leadtrend.com.tw

LD7577-DS-01 January 2009

Fig. 22

dt

dV

Cgd

i

bulk

⋅

=

Fig. 23

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, VCC

and GND.

As shown in figure 24, a small negative spike in

the HV pin may trigger this parasitic SCR and cause the

latchup between VCC and GND. Such latchup will damage

the chip easily because of the equivalent short-circuit

induced.

The LD7577 has eliminated the parasitic SCR efficiently.

Figure 25 shows the equivalent circuit of the LD7577’s Hi-V

structure.

It tells the LD7577 is capable to sustain negative

voltage and superior than similar products. Even though, a

40K

Ω resistor is still recommended to be placed on the Hi-V

path

Fig. 24

Fig. 25