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WRA_S-3WR2 & WRB_S-3WR2

2013.07.22-A/3

Page 6 of 7

TEST CONFIGURATIONS

Input Reflected-Ripple Current Test Setup

Input reflected-ripple current is measured with an inductor Lin and Capacitor Cin to simulate the source impedance.

DC

Cin

Lin

DC

Load

Oscilloscope

Current

Probe

Lin(4.7

µH)

Cin(220

µF, ESR < 1.0Ω at 100 KHz)

DESIGN CONSIDERATIONS

1) Requirement on output load

To ensure this module can operate efficiently and reliably, during operation, the minimum output load could not be less than 5% of the full load,

otherwise output ripple maybe increase dramatically. If the actual output power is very small, please connect a resistor with proper resistance at the

output end in parallel to increase the load, suppose to use the resistance of 5% rated power, or use our company

’s products with a lower rated output

power.

2) Recommended circuit

All the WRA_S-3WR2 & WRB_S-3WR2 series have been tested according to the following recommended test circuit before leaving the factory

(see Figure 6).

If you want to further decrease the input/output ripple, you can increase a capacitance-values properly or choose capacitors with low ESR.

However, the capacitance of the output filter capacitor must be proper. If the capacitance is too big, a startup problem might arise. For every channel

of output, provided the safe and reliable operation is ensured, the greatest capacitance of its filter capacitor must be less than the Max. Capacitive

Load.

General:

Cin1:

5V&12V

100

μF

24V&48V

10

μF

Cin2:

5V&12V

47

μF

24V&48V

1

μF

Lin:

4.7

μH~12μH

Cs:

10

μF~22μF

Cout:

100

μF(Typ.)

Lout:

2.2

μH~10μH

Cd:

47nF/100V

Single output

Dual output

+Vo

0V

Cout

6

7

8

Cs

Cin1

Vin

GND

2

1

3

Vc

R

Lin

Ic

D1

Cd

Cin2

+Vo

0V

Cout

6

8

7

Cout

Lo ut

L out

-Vo

Ci n1

Vin

GND

2

1

Lin

3

Vc

R

Ic

D1

Cd

C in2

(Figure 6)

3) Ctrl Terminal

When open or high impedance, the converter works well; When this pin is

‘high’, the converter shut down. It should be note that the input current

should be between 5-10mA, exceeding the maximum 20mA will cause permanent damage to the converter. The value of R can be derived as follows:

300

-

0

.

1

-

-

C

D

C

I

V

V

R =

For Detailed param eter, please refer to "EMC RECOMMENDED CIRCUIT".

4) Input current

When it is used in unregulated power supply, be sure that the fluctuating range of the power supply and the rippled voltage do not exceed the

module standard. Input current of power supply should afford the flash startup average current of this kind of DC/DC module (Figure 7).

General: Vin:5V

Iave =1110mA

Vin:12V

Iave =640mA

Vin:24V

Iave =325mA

Vin:48V

Iave =160mA

Input Voltage (V)

Input Voltage

Range

Iave

(Figure 7)

5) It is not recommended to increase the output power capability by connecting two or more converters in parallel. The product is not

hot-swappable