BD9C301FJ-LB Datasheet, PDF (8/22 Pages) Rohm – 4.5V to 18V Input, 3.0A Integrated MOSFET Single Synchronous Buck DC/DC Converter

BD9C301FJ-LB
Function Explanations
1. Basic Operations
(1) Enable control
The IC shutdown can be controlled by the voltage applied to the EN pin.
When V_EN reaches 2.0 V (Typ), the internal circuit is activated and the IC starts up.
VEN
the EN pin
VENH
VENL
0
VO
Output setting voltage
0
TSS
Figure 16. On/Off Switching during Enable Control
(2) Protective Functions
The protective circuits are intended for prevention of damage caused by unexpected accidents. Do not use
them for continuous protective operation.
(a) Short Circuit Protection Function (SCP)
The short circuit protection block (SCP) compares the FB pin voltage with the internal reference voltage VREF.
When the FB pin voltage fall below V_SCP（= VREF – 240mV）and with that situation continuing for off latch time, it
latches output in off situation.
Table 1 Short Circuit Protection Function
EN Pin
FB Pin
Short Circuit
Short Circuit
Protection Function Protection Operation
2.0 V or higher
0.8 V or lower
＜V_SCP
＞V_SCP
-
Enabled
Disabled
ON
OFF
OFF
VOUT1
0.8V
FB
SCP threshold：0.56Ｖ
SCP delay time
Typ：1msec
SCP release before counter fix
SCP delay time
Typ：1msec
Soft start
Typ：1msec
HG
LG
IL
OCP
threshold
SCP Protect
HG=H
LG=L
EN
Normal operation
OCP
Normal operation
OCP
SCP
(OFF Latch)
EN threshold
Stand by Normal operation
latch release by EN or UVLO
HG Hi side FET GATE signal
LG : Low side FET GATE signal
Figure 17. Short Circuit Protection function (SCP) timing chart
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TSZ02201-0J3J0AJ00540-1-2
21.Feb.2014 Rev.002