BP5250 Просмотр технического описания (PDF) - ROHM Semiconductor
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BP5250 Datasheet PDF : 12 Pages
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BP5250 / BP5250-24
Application example
(1) Application circuit example is shown in the Fig.4.
BP5250 / BP5250-24
VCTL Vi SW GND IS Vo
123456
Vin
C1
680µF/25V
Q1
C4
SD1
L1 R1
22µH 27mΩ
C2
680µF/16V
VADJ
7
R3 : 30kΩ
C3
Vout
R2
10kΩ
Fig.4
∗Application
Input voltage 12V
Output current 2A
Output voltage 5V
Q1 : 2SJ529S/Hitachi
SD : RB050L-40/ROHM
L1 : CDRH124-220L/Sumida
C1 : 680µF/25V(ZL series)/Rubycon
C2 : 680µF/10V(ZL series)/Rubycon
C3 : 0.1µF/16V
C4 : 0.1µF/25V
R1 : Over-current detection resistance R1=0.068/I(0.068V : offset voltage)
Overcurrent protection characteristic
at R1=27mΩ is shown below.
BP5250 over-current protection
characteristic (Vin=12V)
6.0
5.0
4.0
3.0
2.0
1.0
I
0
0
500 1000 1500 2000 2500
Output current [mA]
R2, R3 : Outpur voltage
Establishment example
establishment resistance
Vo=VADJ × (1+R3/R2)
(R2+R3≤55kΩ)
Vo(V)
8.0
5.0
R2(Ω)
3.3k
10k
R3(Ω)
18k
30k
3.3
20k
33k
2.5
10k
10k
1.5
10k
2k
· There is a posibility that the C1 exceeds the allowable ripple current. Note the allowable ripple
current of the capacitor to be used.
· R2+R3≤55KΩ is recommended for R2,3 to make the most of output voltage accuracy.
· Output voltage range is limited by input voltage. Please refer to the Fig.8.
(2) When the load current is increased.
It is possible by arrangement in a parallel connecting
Q1, 2 and SD1,2
(3) When the power saving function is used.
The output is off when the VCTL pin is set to the
Low or high-impedance.
BP5250 / BP5250-24
VCTL Vi SW GND IS Vo
123456
C4
Q1
L1 R1
Vin
Q2
C1
C2
SD1,2
VADJ
7
R3
C3
Vout
R2
Fig.5
· When Q1 and Q2 are connected parallel, use of a
device with small gate capacity is recommended.
Large gate capacity reduces the switching speed,
which may cause a larger FET loss, exceeding
the allowable loss value.
· When 2SJ529S is connected parallel, the rated load
current 3A is the maximum atVi=12V,Vo=5V
BP5250 / BP5250-24
VCTL Vi SW GND IS Vo
123456
SW
Q1
C4
L1 R1
Vin
C1
SD1
C2
VADJ
7
R3
C3
Vout
R2
Fig.6
4/11
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