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和这个电路很像
" [$ t! d# `- M/ hLoad Dump Protection:
7 E6 c& t* O0 o4 E0 D4.4 Load Dump Protection6 Y% _$ ~$ E) P( R( F
The ISO7637-2 norm, see Section 3.3, “ISO7637-2 Norm”, specifies the load dump test pulse 5: +174V,4 ^5 X% B3 l$ {' n& T0 r* l* `5 T
duration 350ms.3 X# J! I+ }8 Y% B5 U8 ?
In the case of a load dump condition, the Q1 P-MOSFET turns OFF and disconnects the power supply line.
2 c! [7 G' Z. O$ ?Whenever the C3 voltage rises above 32V, the zener diode D4 opens and the Q2 turns OFF the Q1. If the
! |9 Z4 s n- [3 E% u0 ^- `C3 voltage drops down below 32V, the Q2 turns ON the Q1.# j- h z2 m, e& M
The diode D2 limits the Q1 gate-to-source voltage.
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