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PFS7525L/H 数据表(PDF) 4 Page - Power Integrations, Inc. |
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PFS7525L/H 数据表(HTML) 4 Page - Power Integrations, Inc. |
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4 / 37 page ![]() Rev. D 04/25 4 PFS7523-7529/7533-7539 www.power.com Figure 4. Functional Block Diagram. DRAIN (D) Pin: This is the drain connection of the internal power switch. BOOST DIODE CATHODE (K) Pin: This is the cathode connection of the internal Qspeed Diode. Functional Description The HiperPFS-3 is a variable switching frequency boost PFC solution. More specifically, it employs a constant amp-second on-time and constant volt-second off-time control algorithm. This algorithm is used to regulate the output voltage and shape the input current to comply with regulatory harmonic current limits (high power factor). Integrating the switch current and controlling it to have a constant amp-sec product over the on-time of the switch allows the average input current to follow the input voltage. Integrating the difference between the output and input voltage maintains a constant volt- second balance dictated by the electro-magnetic properties of the boost inductor and thus regulates the output voltage and power. More specifically, the control technique sets constant volt-seconds for the off-time (t OFF). The off-time is controlled such that: # VV tK OINOFF 1 -= ^h (1) PI-7226-062215 + - + - BIAS POWER (VCC) BOOST DIODE CATHODE (K) DRAIN (D) SOURCE (S) SIGNAL GROUND (G) POWER GOOD (PG) POWER GOOD THRESHOLD (PGT) REFERENCE (REF) FEEDBACK (FB) UVLO 12 V GATE DRIVER REF SERIES/SHUNT REGULATOR REFERENCE AND BAND GAP VOLTAGE MONITOR (V) HL/LL MON(PFE) INPUT LINE INTERFACE ADC PEAK DETECTOR PF ENHANCER LOW/HIGH LINE DETECT BROWN-IN/ OUT DETECT BO, BI VV + - + - + - + - + - + - COMPENSATION (C) VBRST ~(VO-VIN) FBREF FEEDBACK Pin OV/UV/OFF Off-Time Controller On-Time Controller Integrated Qspeed Ultrafast Diode senseFET Power MOSFET Feedback UV Buffer and De-Glitch Filter Feedback OFF M OFF × (VFB - VV) CINT PON FBREF VPG(H) FBUV FBOFF IOCP FBOV IPGT FBOV + - + - FBUV + - FBOFF + - VFB VPG(H) REF IPGT IOCP ISNS VOFF VE VBRST CINT HL/LL V E PON × MON(PFE) × ISNS VCC Latch START-UP, FMEA CHECKS POWER LIMIT SOA RAMP Frequency Slide MON(PFE) is the switch current sense scale factor which is a function of the peak input voltage OCP HL/LL LEB Feedback OV Non-Linear OTA OTA VOFF is a function of the error-voltage (VE) and is used to reduce the average operating frequency as a function of output power VCC Since the volt-seconds during the on-time must equal the volt-sec- onds during the off-time, to maintain flux equilibrium in the PFC choke, the on-time (t ON) is controlled such that: # Vt K IN ON 1 = (2) The controller also sets a constant value of charge during each on-cycle of the power MOSFET. The charge per cycle is varied gradually over many switching cycles in response to load changes so it can be regarded as substantially constant for a half line cycle. With this constant charge (or amp-second) control, the following relation- ship is therefore also true: # It K IN ON 2 = (3) Substituting t ON from (2) into (3) gives: (4) # IV K K IN IN 1 2 = The relationship of (4) demonstrates that by controlling a constant amp-second on-time and constant volt-second off-time, the input current I IN is proportional to the input voltage VIN, therefore providing the fundamental requirement of power factor correction. |
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