Application Notes
Output Voltage 1.8V-3.3V Ultra High Efficiency 92%
TO-3PL Size, Step-Down Non-Isolated Type DC-DC Converter
10 Watt VSI-mini A Series
(A) Standard Connection
<Technical Notes>
Choice of external capacitors
C1=100µF20WV
C2=2.2µF~4.7µF
C2: No need to add the output capacitor, because it is built in.
In case that the wiring is long to the load, output noise may
be further reduced with the C2 added.
Rating Output Voltage : 3.3V ±5%
Figure5
(B) ON/OFF Control connection
ON/OFF can be controlled by opening or shortening 1pin and 3pin.
Transistor(open collector) is recommended for the open and short
control parts.
Output ON mode
Between 1pin and 3 pin : OPEN
Output OFF mode
Between 1pin and 3 pin : SHORT
Off state voltage 0~0.5Vdc (100µA max.)
Figure6
(C) Output Voltage Adjustment Connection
It is possible to adjust output voltage by connecting a resistor
between 5pin (V.ADJ)and 4pin (+Vout).
The output voltage trim range is as in 3.0~5.0V.
The output voltage adjustable resistor can be calculated by the
following equation.
Output voltage adjustable equation
Rx × Ry × (Vo-Vs)
VR1= Rx × Vs -Ry (Vo-Vs)
Figure7
To adjust output voltage : C3=100µF~220µF
Table 3
VSI-3.3V type calculated value
Vo: Desired Output Voltage
(Vout trim range: 1.8V-3.3V)
4
+Vout
Rx
Rz
Vs
Ry
3
5
V.ADJ
VR1
Load
VR1: Vout variable resistor(down)
Vs=0.8V
Ry=20k ohm
Rx=62.51k ohm
-Vout
Figure8
Note1: When 5pin V.ADJ is open, the output will be the rating value.
Note2: When using a trimmer potentiometer, be careful of the position of the
adjustable lug. We recommend you to confirm the resistor value
in advance, or to start the initial energizing after turning the lug in
the direction of low voltage. And for mass production we recommend
to use a fixed resistor.
Note3: We recommend checking the output voltage value, using converter
after calculating the resistor value.
Note4: When changing output voltage, add C3=100µF~220µF.
Kaga Electronics/Volgen DC-DC CONVERTERS
www.volgen.com
VOLGEN [ VOLGEN KAGA ELECTRONICS INC. ]
