APW7073KE-TY Просмотр технического описания (PDF) - Anpec Electronics
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APW7073KE-TY Datasheet PDF : 25 Pages
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APW7073
Function Descriptions (Cont.)
Under Voltage Protection
The FB pin is monitored during converter operation by
their own Under Voltage (UV) comparator. If the FB
voltage drops below 50% of the reference voltage (50%
of 0.6V = 0.3V), a fault signal is internally generated,
and the device turns off both high-side and low-side
MOSFET and the converter’s output is latched to be
floating.
Switching Frequency
The APW7073 provides the oscillator switching frequency
adjustment. The device includes a 200kHz free-running
triangle wave oscillator. If operating in higher frequency
than 200KHz, connect a resistor from RT pin to the
ground to increase the switching frequency.
Conversely, if operating in lower frequency than
200KHz, connect a resistor from RT to the VCC to
decrease the switching frequency.
Figure 2. shows how to select the resistor for the
desired frequency. Figure 3. shows more detail for
the higher frequencies and Figure 4. shows the lower
frequency detail.
1000
900
800
700
600
500
400
300
200
100
0
200 300 400 500 600 700 800 900 1000
Frequency (KHz)
Figure3. Oscillator Frequency vs. RT Resistance
(High Frequency)
1000
900
800
700
600
1000
900
800
700
600
500
400
300
200
100
0
10
Frequency (KHz)
500
400
300
200
50
70 90 110 130 150 170
Frequency (KHz)
Figure4. Oscillator Frequency vs. RT Resistance
(Low Frequency)
1000
Figure2. Oscillator Frequency vs. RT Resistance
Copyright © ANPEC Electronics Corp.
14
Rev. A.1 - Apr., 2006
www.anpec.com.tw
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