71117 Datasheet, PDF (2/11 Pages) Vishay Siliconix – SI9113 Demonstration Board

Si9113DB
Vishay Siliconix
POWER UP CHECK LIST AND OPERATION
The Si9113D1 and Si9113D2 are designed to operate in
discontinuous mode at nominal line and load conditions. Both
demo boards use the same operational procedure, as follows:
1 Visually inspect the PCB to be sure that all the components
are intact and no foreign substance is lying on the board.
2 Solder the leads at C1 negative and MOSFET Q1 drain to
monitor the drain waveform on the oscilloscope.
3 Reduce the source voltage to zero and connect it through
the dc ammeter at V_IN + and V_IN –. Connect the dc
voltmeter precisely across V_IN + and V_IN –. For the
application where input is of fixed polarity, the diode bridge
BR1 can be eliminated by shorting pin 1 to 4 and pin 2 to
3 to achieve even higher efficiency.
4 Connect the voltmeter precisely across V_OUT1 – Com1 and
V_OUT2 – Com2 for the output voltage measurement.
Connect the oscilloscope ground to C1 negative while the
probe to Q1 drain to observe the switching waveforms.
5 Slowly increase the input voltage while monitoring the input
current meter. Note the input current is less than 10 mA at
18 V_IN and continue to increase the voltage further till the
circuit turns on at approximately 24 V.
6 Set the input voltage to 48 V nominal and monitor the drain
waveform, switching frequency, input and output ripple and
noise.
7 The efficiency, line, load and cross regulation can be
measured by varing the line between 28 to 99 V, and the
load between 10% and 100%.
ACTUAL WAVEFORMS AND PERFORMANCE
Drain Voltage and Current
The circuit is designed to operate in discontinuous mode at
nominal line and full load. The transformer is cleverly designed
to reduce the leakage inductance. Refer to Figure 1 for the
drain voltage and current waveforms. The current starting from
zero indicates the discontinuous mode operation and absence
of any leakage spike at drain shows the tight coupling between
the windings.
V_IN = 28 V
Outputs – Full lLoad
Ch1 – Primary Current (0.1A/div)
Ch3 – Drain Voltage (20 V/div)
FIGURE 1. Drain Voltage and Current Waveform – Si9113D2
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2
44.00
43.00
42.00
41.00
40.00
39.00
38.00
37.00
36.00
0
3.3 V @ 120 mA
3.3 V @ 12 mA
3.00
6.00
9.00
I_OUT2 (mA)
12.00 15.00
FIGURE 2. V_OUT2 (40 V) Load/cross Regulation – Si9113D1
Document Number: 71117
29-Feb-00