BD9141MUV Datasheet, PDF (13/19 Pages) Rohm – Output 2A or More High-efficiency Step-down Switching Regulator with Built-in Power MOSFET

BD9141MUV
Technical Note
VCC
Cin
L
EN
VCC,PVCC
SW
VOUT
VOUT
VOUT
ESR
RO
ITH
GND,PGND
CO
RITH
CITH
Fig.32 Typical application
Stable feedback loop may be achieved by canceling the pole fp (Min.) produced by the output capacitor and the load
resistance with CR zero correction by the error amplifier.
fz(Amp.)= fp(Min.)
1
2π×RITH×CITH
=
1
2π×ROMax.×CO
5. Determination of output voltage
The output voltage VOUT is determined by the equation (6):
VOUT=(R2/R1+1)×VADJ・・・(6) VADJ: Voltage at ADJ terminal (0.8V Typ.)
With R1 and R2 adjusted, the output voltage may be determined as required.
Adjustable output voltage range : 2.5V～6.0V
6
SW
1
ADJ
L
Co
Output
R2
R1
Fig.33 Determination of output voltage
Use 1 kΩ～100 kΩ resistor for R1. if you can use the resistance more than
100kΩor they have a big range between the setting value of output voltage and
input voltage.
8
7.5
7
The minimum input voltage depends on the setting output voltage.
Basically, it is recommended to use in the condition :
6.5
VCCmin = VOUT+1.3V.
It is shown the necessary output current value at the minimum input
6
voltage. (DCR of inductor : 0.1Ω)See Fig.34.
5.5
This data is the characteristic value, so it doesn’t guarantee the
operation range.
5
4.5
0
6.Selection of the reference voltage capacitor (CVREG)
Vo=6.0V
Vo=5.0V
Vo=4.0V
Vo=3.3V
0.5
1
1.5
2
OUTPUT CURRENT : IOUT[A]
VREG voltage is the reference voltage created by Input voltage (Vcc
Voltage). CVREG capacitor should be selected 0.1uF or more.
Fig.34 minimum input voltage in each output voltage
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13/18
2009.06 - Rev.A