ncp1927 ON Semiconductor, ncp1927 Datasheet
ncp1927
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ncp1927 Summary of contents
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... Timer−Based Overload Protection with Auto−Recovery • Protection Against Winding Short−Circuit • Soft−Start Timer • 800 mA Source / 1200 mA Sink Gate Drive 1 Publication Order Number: IENABLE PSKIP PDRV VCC FDRV GND FFB FCS † Shipping 2500 / Tape & Reel NCP1927/D ...
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Figure 1. Typical Application Example http://onsemi.com 2 ...
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Flyback_OVLD GOS Timer GTS R GTS GTS Timer V standby 30 ms Filter V UVP 30 ms POVUV Filter OVP_int I UVP V OVP V disable PControl(boost) PFC_OK 0.955*V REF PFB V REF 0 mA Detect PControl ...
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PIN FUNCTION DESCRIPTION Pin No. Pin Name 1 POVUV The gate drive is disabled while V typical). 2 PFB This pin receives a portion of the pre−converter output voltage. This information is used for the regulation and the “output low” ...
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MAXIMUM RATINGS (Note 1) Rating Supply Pin (pin 13) (Note 2) Voltage Range Current Range PFC Drive Pin (pin 14) (Note 2) Voltage Range Current Range Flyback Drive Pin (pin 12) (Note 2) Voltage Range Current Range Inverter Enable Pin ...
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ELECTRICAL CHARACTERISTICS 2 PSKIP FFB FCS values T = 25°C, for min/max values − 25°C to 125°C, unless otherwise noted Characteristics SUPPLY ...
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ELECTRICAL CHARACTERISTICS 2 PSKIP FFB FCS values T = 25°C, for min/max values − 25°C to 125°C, unless otherwise noted Characteristics FLYBACK ...
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ELECTRICAL CHARACTERISTICS 2 PSKIP FFB FCS values T = 25°C, for min/max values − 25°C to 125°C, unless otherwise noted Characteristics PFC ...
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ELECTRICAL CHARACTERISTICS 2 PSKIP FFB FCS values T = 25°C, for min/max values − 25°C to 125°C, unless otherwise noted Characteristics PFC ...
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... This device includes frequency jittering, a shutdown input, an inverter enable output standby input, and a dedicated pin for under/overvoltage protection. SUPPLY SEQUENCING The flyback controller of the NCP1927 is enabled once V reaches V , provided it is not in thermal shutdown CC CC(on) and has not been latched off or shutdown. Once the flyback controller is enabled, a soft− ...
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... The Shutdown pin allows for external disabling of the NCP1927. When V threshold, V PFC drive outputs are immediately turned off, and a V hiccup occurs (see Figure 5). When V the cycle repeats unless the NCP1927 is taken out of shutdown. This is achieved when V than V SHDN start when V Time power− ...
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... OSC MOD Figure 7. Frequency Jittering Current Sensing NCP1927 is a current−mode controller, which means that the feedback voltage sets the peak current flowing in the transformer and the MOSFET. This is done through the PWM comparator. The switch current is sensed across a resistor and the resulting voltage is applied to the FCS pin. ...
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... R (typically 20 kW). FFB Soft−Start The NCP1927 flyback controller features an internal soft−start circuit. Every time the controller starts (i.e. the controller was off and starts, or restarts due to a fault), a soft−start is applied when V limit threshold is linearly increased from 0 until it reaches V (in 4 ...
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When calculating the proper value for R necessary to express the internal ramp signal in terms of its slope (dI /dt). This is done using Equation 3. OSC ramp(MAX) OSC + dt D MAX The inductor ...
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Soft−Skip timer instead of the feedback voltage. Since the LEB of the FCS Pin prevents operation at nearly 0% duty ratio, the controller instead compares the soft−skip ramp to an internal ...
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... Figure 18. The MOSFET off time varies based on the instantaneous line voltage, but the on time is constant. This causes the peak inductor current (I follow the ac line voltage. The NCP1927 implements ideal choice for medium power PFC boost stages because it combines the lower peak currents of CCM operation with the zero current switching of DCM operation ...
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... Output Regulation The NCP1927 error amplifier (EA) consists of an operational transconductance amplifier (OTA) with the inverting input connected to the PFB pin and the output connected to the PControl pin to regulate the output voltage. It features a typical transconductance (gm) of 200 mS and a maximum output (I and I EA(SRC) EA(SNK) (typical). The non− ...
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... PFC stage to prevent it from interfering with the operation of the soft−start circuit. On Time Control Since the NCP1927 is designed to control a CrM boost converter, the switching pattern consists of constant on times and variable off times. The on time is set via an external capacitor (C ) connected to the PCT pin ...
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... ZCD signal may be too small to cross the ZCD thresholds. Frequency Clamp Since the NCP1927 operates in CrM mode over the ac line half cycle, the switching frequency naturally increases as the line voltage approaches zero. In order to minimize the PFC ...
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... POVUV Pin is floating). The output voltage that causes a UVP fault is calculated using Equation 14. time V out(UVP) Overcurrent Protection (OCP) The NCP1927 contains an OCP circuit to protect the PFC time stage by limiting the coil current. A current sense resistor ( inserted in the return path to generate a negative sense voltage proportional to the coil current (V portrayed by Figure 27 ...
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... Skip Mode Operation The NCP1927 automatically skips switching cycles when the power demand drops below a given level. This is accomplished by monitoring the internal offset PControl voltage. This voltage is compared to the PCT ramp to control the power level in a particular design. During normal operation, the circuit generates the input line current necessary for matching the load power demand ...
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... GTS IENABLE Pin The IENABLE pin is designed to drive an optocoupler that enables the Flat Panel TV backlight inverter once the PFC stage reaches regulation. The NCP1927 achieves this by monitoring the current sourced by the EA. Once this current drops to 0 mA, the IENABLE pin voltage switches R ...
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... Mounting Techniques Reference Manual, SOLDERRM/D. Soft−Skip is a trademark of Semiconductor Components Industries, LLC (SCILLC). The products described herein (NCP1927) may be covered by one or more of the following U.S. patents: 7,583,522. There may be other patents pending. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein ...