BD9E302EFJ Datasheet, PDF (30/44 Pages) Rohm – Integrated MOSFET Single Synchronous Buck DC/DC Converter

BD9E302EFJ
Datasheet
 Selection of Components Externally Connected
About the application except the recommendation, please contact us.
Parameters required to design a power supply are as follows.
Parameter
Input Voltage
Output Voltage
Switching Frequency
Inductor ripple current
ESR of the output capacitor
Output capacitor
Soft-start time
Max output current
Symbol
VIN
VOUT
FOSC
∆IL
RESR
COUT
TSS
IOMAX
Value Example
24 V
5V
550kHz(Typ)
1.13A
10mΩ
44μF(22μF×2)
2.5ms(Typ)
3A
1. Switching Frequency
Switching frequency is fixed to FOSC = 550kHz (Typ).
2. Output Voltage Set Point
The output voltage value can be set by the feedback resistance ratio.
V _OUT
R₁ R₂
R₂
0.8 [V]
※ Minimum pulse range that can be produced at the output
stably through all the load area is 200nsec for
BD9E302EFJ.
Use input/output condition which satisfies the following
method.
Figure 74. Feedback Resistor Circuit
200 nsec
≤_V
V
IN
OUT
F_OSC
Please set feedback resistor R1 + R2 below 700 kΩ . In addition, since power efficiency is reduced with a small R1 + R2,
please set the current flowing through the feedback resistor to be small as possible than the output current IO.
3. Input capacitor configuration
For input capacitor, use a ceramic capacitor. It will more effective as close as possible to the VIN pin. The rating voltage of
input capacitor should be 2 times of VIN supply and 1.2 times of maximum VIN supply is commanded. For normal setting,
10μF is recommended, but with larger value, input ripple voltage can be further reduced. Also, for capacitance of input
capacitor, take temperature characteristics, DC bias characteristics, etc. into consideration, minimum value no less than
4.7μF. In order to reduce the influence of high frequency noise, 0.1μF ceramic capacitor placed as close as possible to the
VIN pin is commanded.
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27.Apr.2016 Rev.002