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MV1012SC 数据表(PDF) 7 Page - Shindengen Electric Mfg.Co.Ltd |
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MV1012SC 数据表(HTML) 7 Page - Shindengen Electric Mfg.Co.Ltd |
7 / 33 page MV1012SC 6 2. Explanation of basic operations The MV1012SC is a critical conduction mode (CRM) step-down chopper control IC. Figure 1 shows the circuit configuration. Figure 2 shows the waveforms of currents flowing to the MOSFET and the diode, represented by Id and IF, respectively. In a general CRM step-down chopper circuit, the MOSFET is turned on after the IF becomes zero, leaving little recovery current for the diode and lower losses and noises than a PWM circuit. Meanwhile, disadvantageously, the oscillation frequency changes dramatically as the output current (LED current) changes, resulting in poorer dimming characteristics and efficiency. The MV1012SC detects Id, converted to a voltage, with the current detection pin (CS pin). When it reaches the CS reference voltage, the MV1012SC turns the MOSFET off (peak current detection). The IC performs CRM control in this way: When the diode current IF becomes zero, the Svout voltage falls below the Svin voltage, so the IC detects this state (zero current detection) and turns the MOSFET on. The voltages on both ends of the choke (① and ② in Figure 2) are divided with resistors and input to the Svin pin and the Svout pin to achieve CRM operations without auxiliary winding. Additionally, the off-time modulation prevents the frequency increasing during dimming and achieves constant high efficiency and dimming characteristics during deep dimming. (See Section 5 [Dimming characteristics] on page 19.) Figure 1 CRM step-down chopper circuit Figure 2 MOSFET and diode current waveforms of the CRM step-down chopper and voltage waveforms on both ends of the choke Ip Io Vi Vo Detect intersection IF Id Delay in detection by IC + gate delay 0 0 CAT.No.1A0602-1E |
类似零件编号 - MV1012SC |
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类似说明 - MV1012SC |
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