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LC201S データシート(PDF) 8 Page - Sanken electric |
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LC201S データシート(HTML) 8 Page - Sanken electric |
8 / 13 page LC201S LC201S-DS Rev.1.2 SANKEN ELECTRIC CO.,LTD. 8 Mar. 30, 2016 Figure 8-3 The reference startup time of OUT2 pin After startup, there is two way of suppplying power to IC. In case the power of IC continues to be supplied via ST pin , OUT1 pin voltage becomes VOUT1 (9V or 20V refer to Table 8-1). In case the power of IC is supplied from external power supply, OUT1 pin is connected to the auxiliary winding of external power supply. Since the power supply pin can be switched from ST pin to OUT1 pin, the power dissipation of the startup circuit can be eliminated after startup process. VAC C1 D2 C2 D P BR1 OUT1 GND ST 8 1 5 U1 VD External power supply Figure 8-4 In case the power of IC is supplied from external power supply After external power supply starts, when the auxiliary winding voltage, VD, is lower than VOUT1, OUT1 pin voltage keeps VOUT1. When VD increases and OUT1 pin voltage becomes higher than VOUT1, the startup circuit of IC is cut automatically. Then OUT1 pin voltage becomes the rectified and smoothed VD voltage. The number of turns of auxiliary winding D is set such that OUT1 pin voltage, VOUT1(D), becomes within the range of Expression (1) in the specification of the input voltage range and output load range of the power supply. V 35 V V OUT1(D) UVH (1) Where, VUVH is UVLO Operation Stop Voltage. VUVH depends on the setting of SL pin (refer to Table 8-2). The diode D2 should be a fast recovery diode since a high frequency switching current flows to D2. 8.3 Current Sink Function When the output voltage of OUT2 pin is OFF, the Current Sink Function prevents the output voltage of OUT2 pin from varying by external factor. When this function is used, SINK pin is connected to OUT2 pin as shown in Figure 8-5. GND 1 U1 UVLO Linier Regulator 5 OUT2 OUT1 4 SINK R1 ISINK 3 QSI Figure 8-5 SINK pin peripheral circuit Figure 8-6 shows Current Sink Function operational waveforms. When OUT1 pin voltage decreases UVLO Operation Stop Voltage, VUVL, the output of OUT2 pin becomes Low state. At the same time, QSI turns on and the sink current flows into SINK pin. Thus the output of OUT2 pin is fixed Low state immediately. When OUT1 pin voltage increases to UVLO Operation Start Voltage, VUVH, or more, QSI turns off and OUT2 pin outputs VOUT2 = 5 V. The value of R1 connected between SINK pin and OUT2 pin should be selected considering the range of the absolute maximum ratings of SINK pin current. OUT1 pin voltage ST pin current VUVH VUVL ISINK OUT2 pin voltage 5V Figure 8-6 Current Sink Function operational waveforms. 0.001 0.01 0.1 1 1 10 100 Capacitance of C2 (μF) SL=Open SL=0V |
同様の部品番号 - LC201S |
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同様の説明 - LC201S |
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