BP5250/BP5250-24

The BP5250/BP5250-24 are DC/DC converters for step-down that can drive PchFET using PWM system.
The voltage setting resistor and the combination of external power elements enable you to make any power
circuit to your liking. High-efficient DC/DC converter can be made easy by adding external components such
as I/O smoothing capacitor without designing circuit.

Applications

OA appliances(copy machine,personal computer, facsimile), AV appliances (car navigation, DVD etc.),
and industrial appliances.

Features

1) High power conversion(

=90% Vin=12V 5V/2A)

2) Power save pin(Leakage current at OFF mode : IR=10

AMAX)

3) Output voltage can be established from 1.5V to 9V in the VADJ pin.(For BP5250, however, output voltage is
limted by input voltage.)
4) With recovery type overcurrent protection function (Detection current can be established by the external
current detection resistance.)
5) Power circuit can be made easy by adding external smoothing capacitor and power element.
6) Reference voltage accuracy 1.25V

Absolute maximum ratings (Ta=25

Recommended operating conditions (Ta=25

DC/DC converter

Parameter

Symbol

Limits

Unit

Input voltage

ESD endurance

Operating temperature range

Storage temperature range

Allowable max surface temperature

The power saving terminal voltage

Vsurge

Topr

Tstg

Tfmax

CTL

BP5250

100

BP5250-24

Condition

(EIAJ ED4701-1C-111A)

Ambient temperature+The module self-heating

Tfmax

VCTL

Parameter

Symbol

Unit

Max.

Typ.

Min.

BP5250

BP5250-24

Input voltage

1/11

BP5250 / BP5250-24

Pin descriptions

Block diagram

CONTROL CIRCUIT

DRIVE CIRCUIT

OVER CURRENT

DETECTION CIRCUIT

CTL

GND

ADJ

Pin No.

Pin name

Function

CTL

GND

ADJ

Power save terminal.Setting the voltage on this terminal to Low or high impedance turns the
output OFF. Normally connect to Vi for use.

Input voltage terminal. Inserting a bypass capacitor of 0.1

F between this and pin 4 GND is

recommended.

Terminal to drive the external FET gate.

GND terminal. Connect the negative terminal of the I/O smoothing capacitor and the anode terminal
of the flywheel diode nearby.
Overcurrent detection terminal. The value of the resistor inserted between this and pin 6 sets the
output current capacity.

Output voltage monitor terminal.
Output voltage setting terminal. The values of the resistors inserted between this and pin 6 and
between this and GND set the output voltage capacity.

2/11

BP5250 / BP5250-24

Measurement circuit

Fig.1 Output ADJ terminal voltage measurement circuit

Vi=12V : BP5250
Vi=24V : BP5250-24

CTL

GND

ADJ

BP5250 / BP5250-24

ADJ

Fig.2 Over current detection off set voltage measurement circuit

Vi=12V : BP5250
Vi=24V : BP5250-24

Over current detection off set voltage 1 : V

ADJ

=1.25V

Over current detection off set voltage 2 : V

ADJ

=0V

CTL

GND

ADJ

BP5250 / BP5250-24

ADJ

Fig.3 Control terminal voltage sink current ·

Stand by sink current measurement circuit

Vi=12V : BP5250
Vi=24V : BP5250-24

CTL sink current : V

CTL

=5V

Stad by current : V

CTL

=0V

CTL

GND

ADJ

STB

ADJ

1.25V

BP5250 / BP5250-24

Electrical characteristics (Unless otherwise noted, Vi=12V : BP5250, Vi=24V : BP5250-24, Ta=25

Parameter

Symbol

Min.

Typ.

Max.

Unit

Conditions

1.225

ADJ

LT1

LT2

CTLH

CTLL

CTL

STB

Output ADJ Pin voltage

Over current detection

off set voltage1

Over current detection

off set voltage2

CTL pin ON voltage

CTL pin OFF voltage

CTL sink current

Stand by current

1.25

-
-

1.275

Test Circuit

Fig.1

Fig.2

Fig.3

VSW L

H V

ADJ

=1.25V

VSW L

H V

ADJ

=0V

VSW H

VSW L

CTL

=5V

CTL

=0V

3/11

BP5250 / BP5250-24

(2) When the load current is increased.

It is possible by arrangement in a parallel connecting
Q1, 2 and SD1,2

Fig.5

Vout

Vin

SD1,2

CTL

GND

ADJ

BP5250 / BP5250-24

· 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

(3) When the power saving function is used.

The output is off when the V

CTL

pin is set to the

Low or high-impedance.

Fig.6

Vout

Vin

SD1

CTL

GND

ADJ

BP5250 / BP5250-24

Application example

(1) Application circuit example is shown in the Fig.4.

Application

Input voltage 12V
Output current 2A
Output voltage 5V

Q1 : 2SJ529S/Hitachi
SD : RB050L-40/ROHM
L1 : CDRH124-220L/Sumida
C1 : 680

F/25V

(ZL series)

/Rubycon

C2 : 680

F/10V

(ZL series)

/Rubycon

C3 : 0.1

F/16V

C4 : 0.1

F/25V

Fig.4

· 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

55K

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.

R1 : Over-current detection resistance R1=0.068/I

(0.068V : offset voltage)

Overcurrent protection characteristic

at R1=27m

is shown below.

R2, R3 : Outpur voltage
establishment resistance

Establishment example

Vo=VADJ

(1+R3/R2)

(R2+R3

55k

)

Vo(V)

R2(

)

R3(

)

8.0

5.0

3.3

2.5

1.5

3.3k

10k

20k

10k

18k

30k

33k

10k

Output current [mA]

BP5250 over-current protection

characteristic (Vin=12V)

Output voltage [v]

6.0

5.0

4.0

3.0

2.0

1.0

500

1000

1500

2000

2500

Vout

Vin

R2
10k

27m

R3 : 30k

SD1

C2
680

F/16V

C1
680

F/25V

CTL

GND

ADJ

BP5250 / BP5250-24

4/11

BP5250 / BP5250-24

Output voltage establishment and application circuit example

Application example

Input voltage 12V
Output voltage 5V

Q1 : 2SJ529S/hitachi

R1 : 27m

/SUSUMU

SD : RB050L-40/ROHM

R2 : 10k

/ROHM

L1 : CDRH124-220L/Sumida

R3 : 30k

/ROHM

C1 : 680

F/25V

(ZL seried)

/Rubycon

C2 : 680

F/16V

(ZL series)

/Rubycon

C3 : 0.1

F/16V/ROHM

C4 : 0.1

F/25V/ROHM

Fig.9

Vout

Vin

SD1

CTL

GND

ADJ

BP5250-BP5250-24

Caution note for operation

(1) Output voltage establishment range is changed by input voltage.Please refer to the Fig.8.
(2) Layout of external parts may significantly change the output spike noise or characteristics or cause abnomal
oscillation and temperature increase. Note the following for layout.

· Provide the input smoothing electroytic capacitor close to the FET source and pin 2 of the module.
· Provide the output smoothing electrolytic capacitor close to pin 6 of the module together with the

current detection resistor
· Large current may run into the coil, current detection resistor and output through the FET source-
drain.Try to use a solid pattern as much as possible.

· FET drain, coil and flywheel diode may generate heat by power loss. Try to use a solid pattern so that the

heat may be released. Measure a rise in temperature of each element and make sure that it is not
abnormal.

· Provide the negative terminal of the I/O smoothing capacitor and anode terminal of the flywheel diode

close to GND pin 4 of the module.

· Connect the negative terminal of the I/O smoothing electrolytic capacitor and anode terminal of the

flywheel diode nearby.
(3) Output load may cause large ripple current in the I/O smoothing electrolytic capacitor. Note the allowable
ripple current of the capacitor to be used.
(4) As the output smoothing electrolytic capacitor, one with especially low impedance is recommended for
suppresing output ripple voltage. Select a capacitor suited for the use.
(5) Please be sure to use protection circuit function.(R1 should not be 0

Output voltage establishment range

Output voltage establishment range is changed by input voltage.Please refer to the Fig.8.

Vi [V]

Vo characteristic

Output voltage

establishment [v]

10 12 14 16 18 20

28 30

22 24 26

24V

17V

1.5V

BP5250

BP5250-24

Fig.8

5/11

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: BP5250-24

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: BP5250-24