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date 09/05/2012 │ page 5 of 6CUI Inc │ SERIES: VWRBS1 │ DESCRIPTION: DC-DC CONVERTER
1. Requirement on Output Load
In order to ensure the product operates effi ciently and reliably, make sure the specifi ed range of input voltage is not exceeded and
the minimum output load is not less than 10% load. If the actual load is less than the specifi ed minimum load, the output ripple may
increase sharply while its effi ciency and reliability will reduce greatly. If the actual output power is very small, please add an
appropriate resistor as extra loading.
2. Overload Protection
Under normal operating conditions, the output circuit of these products has no protection against overload. The simplest method is to
connect a self-recovery fuse in series at the end or add a circuit breaker to the circuit.
3. Recommended Circuit
All VWRBS1 converters have been tested according to the following recommended testing circuit before leaving the factory. This
series should be tested under load, never under no load (Figure 1).
However, the capacitance of the output fi lter 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 fi lter capacitor sees
(Table 1).
General:
4. CTRL Terminal
When open or high impedance, the converter work well; When this pin is ‘high’; the converter shutdown; It should be note that the
input current should between 5~10 mA, exceeding the maximum 20 mA will cause permanence damage to the converter.
The value of R can be derived as follows:
5. Input Current
While using unstable power source, please ensure the output voltage and ripple voltage do not excced indexes of the converter. The
preceding power source must be able to provide for converter suffi cient starting current Ip.
General: Ip ≤1.4*Iin-max
6. No parallel connection or plug and play
+Vo
0V
Co ut
6
7
8
Cs
Cin
Vi n
GND
2
1
3
Vc
R
Lin
Ic
D1
Vout
(Vdc)
Cout
(μF)
3.3 2,200
5 1,000
9 680
12 470
15 330
Table 1
APPLICATION NOTES
Input Current(A)
Input Volta
e
V
Input Voltage
Range
Ip
Figure 1
Cin
5, 12 V 100 μF
24, 48 V 10 μF
Cout 47 μF typ.
Lin 4.7~120 μH
Lout 2.2~10 μH
Cs 10~22 μF
5 Vdc models 12 Vdc models 24 Vdc models 48 Vdc models
1,000 mA slow-blow type 500 mA slow-blow type 250 mA slow-blow type 120 mA slow-blow type
R=
V
C
-V
D
-1.0
I
C
For more information, please visit the product page.
