BD9D321EFJ Datasheet, PDF (2/28 Pages) Rohm – 4.5V to 18V Input, 3.0A Integrated MOSFET 1ch Synchronous Buck DC/DC Converter

BD9D321EFJ
Pin Configuration
EN ₁
FB ₂
VREG 3
SS ⁴
(TOP VIEW)
8 VIN
7 BOOT
6 SW
5 GND
Figure 2. Pin Assignment
Datasheet
Pin Descriptions
Terminal
No.
1
Symbol
Function
Turning this terminal signal low level (0.3 V or lower) forces the device to enter the shutdown
EN mode. Turning this terminal signal high level (2.2 V or higher) enables the device. This
terminal must be terminated.
2
FB
An inverting input terminal of comparator which compares with reference voltage (V_REF).
Refer to page.17 for how to calculate the resistance of the output voltage setting.
Power supply voltage terminal inside IC.
3
VREG Voltage of 5.25V (Typ) is outputted with more than 2.2V is impressed to EN terminal.
Connect 1µF ceramic capacitor to ground.
4
SS
Terminal for setting the soft start time. The rise time of the output voltage can be specified by
connecting a capacitor to this terminal. Refer to page.17 for how to calculate the capacitance.
5
GND Ground terminal for the output stage of the switching regulator and the control circuit
Switch node. This terminal is connected to the source of the high-side MOSFET and drain of
6
SW
the low-side MOSFET. Connect a bootstrap capacitor of 0.1µF between this terminal and
BOOT terminal. In addition, connect an inductor considering the direct current
superimposition characteristic.
7
BOOT
Connect a bootstrap capacitor of 0.1µF between this terminal and SW terminal.
The voltage of this capacitor is the gate drive voltage of the high-side MOSFET.
8
VIN
Power supply terminal for the switching regulator.
Connecting a 20µF(10µF×2) and 0.1µF ceramic capacitor to ground is recommended.
-
FIN
A backside heat dissipation pad. Connecting to the internal PCB ground plane by using
multiple via provides excellent heat dissipation characteristics.
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TSZ22111•15•001
2/25
TSZ02201-0J3J0AC00490-1-2
07.Aug.2013 Rev.001