BD9E301EFJ-LB Datasheet, PDF (17/33 Pages) Rohm – 7.0V to 36V Input, 2.5A Integrated MOSFET Single Synchronous Buck DC/DC Converter

BD9E301EFJ-LB
Function Description
1. Enable Control
The IC shutdown can be controlled by the voltage applied to the EN terminal. When EN voltage reaches 2.5V (Typ), the
internal circuit is activated and the IC starts up. Setting the shutdown interval (Low Level interval) of EN to 100µs or longer
will enable the shutdown control with the EN terminal.
VEN
EN terminal
VENH
VENL
0
t
VOUT
Output Voltage
VOUT×0.85
0
t
TSS
Figure 41. Timing Chart with Enable Control
2. Protective Functions
The protective circuits are intended for the prevention of damages caused by unexpected accidents. Do not use
them for continuous protective operation.
(1) Short Circuit Protection (SCP)
The short circuit protection block compares the FB terminal voltage with the internal reference voltage VREF. When
the FB terminal voltage has fallen below 0.85V (Typ) and remained in that state for 1.0msec (Typ), SCP activates and
stops the operation for 16msec (Typ) and subsequently initiates a restart.
EN pin
2.5V or higher
0.8V or lower
VOUT
Table 1. Short Circuit Protection Function
FB pin
Short circuit protection
0.30V (Typ)≧FB
0.30V (Typ)＞B≧0.85V (Typ)
Enabled
FB＞0.85V (Typ)
-
Disabled
Switching Frequency
142.5kHz (Typ)
285kHz (Typ)
570kHz (Typ)
OFF
Soft start
3.0msec (typ.)
1.0V
FB terminal
SCP threshold voltage：
0.85Ｖ(typ.)
SCP detection time
1.0msec (typ.)
SCP detection released
SCP detection time
1.0msec (typ.)
Upper MOSFET
gate
Lower MOSFET
gate
Inductor
current
IC internal
SCP signal
OCP
Threshold
LOW
LOW
16msec (typ.)
Figure 42. Short Circuit Protection (SCP) Timing Chart
SCP reset
www.rohm.co
© 2013 ROHM Co., Ltd. All rights reserved.
TSZ22111•15•001
17/30
TSZ02201-0J3J0AJ00380-1-2
21.Feb.2014 Rev.002