BD8628EFV_09 Datasheet, PDF (11/15 Pages) Rohm – FET Controller Type 3ch System Power Supply ICs

BD8628EFV, BD8624EFV
Technical Note
●Protection function
Protection circuit is effective for destruction prevention due to accident so that avoid using by continuous protection operation.
Low voltage protection function(LVP)
Low voltage protection function detects set output voltage VO from FB terminal and off-latched DC/DC converter compared
to internal reference level.
Low voltage protection function operates when FB terminal voltage falls below VLVP (=0.7 x VREF) and continues more than
set time in external resistance.
Table 4 Low voltage protection function
CTL
terminal
>VIHCTL
SS terminal
>1.1V(typ)
FB terminal
<VLVP
>VLVP+VLVP_HYS
Low voltage
protection function
Enable
Low voltage
protection operation
ON
OFF
<1.0V(typ)
-
Disable
OFF
<VILCTL
-
-
Disable
OFF
※Constant voltage protection function is enabled when SS terminal voltage becomes more than 1.1V (typ) in the
transition to ON control (during soft start).
Overvoltage protection function (OVP)
Overvoltage protection function detects set output voltage VO from FB terminal and off-latched DC/DC converter controller
compared to internal reference level.
Overvoltage protection function operates when FB terminal voltage exceeds VOVP (=1.2 x VREF) and continues more than
set time in external resistance.
Table 5 Overvoltage protection function
CTL
terminal
>VIHCTL
<VILCTL
SS terminal
>1.1V(typ)
<1.0V(typ)
-
FB terminal
>VOVP
<VOVP
-
-
Overvoltage protection
function
Enable
Disable
Disable
Overvoltage protection
operation
ON
OFF
OFF
OFF
※Overvoltage protection function is enabled when SS terminal voltage of each Ch becomes more than 1.1V (typ) in
the transition to ON control (during soft start).
VFB
FB
terminal voltage
0
0.7×VREF+VLVP_HYS
1.2×VREF
VREF
0.7×VREF
Protection
ON
OFF
LVP
OVP
LVP
PDET
Hi-Z
terminal
LOW
Figure.5 Low voltage / overvoltage protection
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11/14
2009.05 - Rev.A