CUI Inc │ SERIES: VWQBS2-SIP │ DESCRIPTION: DC-DC CONVERTER
date 09/10/2012 │ page 4 of 5
APPLICATION NOTES
1. Requirement on Output Load
To ensure this module can operate efficiently and reliably, During operation, the minimum output load is not less than 10% of the full
load, and that this product should never be operated under no load! 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, or use our company’s products with a lower rated
output power.
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 input end or add a circuit breaker to the circuit.
Vin
(Vdc)
Fuse (slow-blow type)
(mA)
24
48
250
150
3. Recommended Circuit
If you want to further decrease the input/output ripple, an “LC” filtering network may be connected to the input and output ends of
the DC/DC converter, see (Figure 1).
D1
R
Ic
Vc
3
Lin
2
1
6
Figure 1
Vin
+Vo
0V
C1
C2
Cout
GND
9
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 see
(Table 1).
C1/C2
10 ~ 100 μF
4.7 ~ 120 μH
100 μF
Lin
Cout
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
Vc not limited and desirable 5 Vdc, 12 Vdc, or directly with Vin. The value of R can be derived as follows:
VC-VD-1.0
R=
IC
5. Input Current
Nominal input voltage range. The input current of the power supply must be sufficient to the startup current (Ip) of the DC-DC
module.
General: Ip ≤1.4*Iin-max
Ip
Input Voltage
Range
Input Voltage (V)
6. No parallel connection or plug and play
Table 1
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