BD91361MUV_14 Datasheet, PDF (17/27 Pages) Rohm – Synchronous Buck Converter with Integrated FET

BD91361MUV
Datasheet
(5) Setting the Output Voltage
The output voltage VOUT is determined by the equation (6):
V_OUT  R₂ / R₁ 1V_ADJ ・・・(6)
Where:
VADJ: Voltage at ADJ terminal (0.8V Typ)
The required output voltage may be determined by adjusting R1 and R2.
6
SW
1
ADJ
L
CO
Output
R2
R1
Adjustable output voltage range: 0.8V to 3.3V
Figure 37. Determination of Output Voltage
Use 1 kΩ to 100 kΩ resistor for R1. If the resistance is higher than 100 kΩ, carefully check the assembled set for
ripple voltage etc.
3.7
The lower limit of input voltage depends on the output
voltage.
Basically, the recommended operating condition is
3.5
V_CCMin V_OUT  1.2V
3.3
V_O=2.5V
Figure 38. shows the necessary output current value at the
3.1
lower limit of input voltage. (DCR of inductor : 20mΩ)
This data is the characteristic value, so it’ doesn’t guarantee
the operation range.
2.9
V_O=2.0V
V_O=1.8V
8. BD91361MUV Cautions on PC Board Layout
2.7
0
1
2
3
Output Current : IOUT[A]
Figure 38. Minimum Input Voltage in Each Output Voltage
Figure 39. Layout Diagram
(1) Layout the input ceramic capacitor CIN as close as possible to the PVCC and PGND pins, and the output capacitor
CO as close as possible to the PGND pin.
(2) Layout CITH and RITH between the pins ITH and GND as near as possible with the shortest possible trace.
Note: VQFN020V4040 (BD91361MUV) has thermal PAD on the reverse of the package.
The package thermal performance may be enhanced by bonding the PAD to GND plane which occupies a large
area of the PCB.
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