UC1852 UC2852 UC3852

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UC1852 UC2852 UC3852
High Power-Factor Preregulator
FEATURES Low-Cost Power Factor
Correction
DESCRIPTION
UC1852 provides low-cost solution active power-factor correction (PFC) systems that would otherwise draw high peak current pulses from power lines. This circuit implements zero-current switched boost conversion, producing sinusoidal input currents with minimum external components, while keeping peak current substantially below that fully-discontinuous converters. UC1852 provides controlled switch on-time regulate output bulk voltage, off-time defined boost inductor, zero-current sensing circuit reactivate switch cycle. Even though switching frequency varies with both load instantaneous line voltage, maintained within reasonable range minimize noise generation. While allowing higher peak switch currents than continuous PFCs such UC1854, this device offers less external circuitry smaller inductors, better performance easier line-noise filtering than discontinuous current PFCs with sacrifice complexity cost. ability obtain power factor excess 0.99 makes UC1852 optimum choice low-cost applications watt power range. Protection features these devices include under-voltage lockout, output clamping, peak-current limiting, maximum-frequency clamping. UC1852 family available 8-pin plastic ceramic dual in-line packages, 8-pin small outline package (SOIC). UC1852 specified operation from -55°C +125°C, UC2852 specified operation from -40°C +85°C, UC3852 specified operation from +70°C.
Power Factor Greater Than 0.99 External Parts Required Controlled On-Time Boost Zero-Current Switching Limited Peak Current Frequency Limits Starting Current Less Than High-Current Drive Output Under-Voltage Lockout
TYPICAL APPLICATION
UDG-92001
10/94
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (Low-impedance Source).30.0V Supply Current (High-impedance Source) .30.0mA Current, Peak .±1.0A Energy, Capacitive Load. 5.0µJ Input Voltage, ISNS .±5.0V Input Voltage, VFB. -0.3V +10.0V COMP Current .±10.0mA ISET Current.-10.0mA Power Dissipation Ta25°C (Note .1.0W Storage Temperature -65°C +150°C Lead Temperature (Soldering, Seconds) +300°C Note voltages with respect (Pin Note currents positive into specified terminal. Note Refers DIL-8 Package. Consult Packaging Section Unitrode Integrated Circuits databook thermal limitations considerations package.
CONNECTION DIAGRAM
UC1852 UC2852 UC3852
DIL-8 (TOP VIEW) Package
SOIC-8 (TOP VIEW) Package
UDG-92002
ELECTRICAL CHARACTERISTICS Unless otherwise stated, VCC=24V, ISET=50k GND, RAMP=1nF GND, ISNS=
-0.1V, connected COMP, load OUT, -55°C<Ta<+125°C UC1852, -40°C<Ta<+85°C UC2852, 0°C<Ta<+70°C UC3852, Ta=Tj. PARAMETER Timer Section ISET Voltage RAMP Charge Current RAMP Discharge Current RAMP Saturation Voltage RAMP Threshold Maximum Frequency RAMP Threshold Comparator Current Sense Comparator ISNS Restart Threshold ISNS Fault Threshold ISNS Input Current Error Amplifier Section Input Voltage Input Bias Current COMP Sink Current COMP Source Current COMP Clamp Voltage Output Saturation Voltage High Saturation Voltage Saturation Voltage 10mA Clamp Voltage Voltage during UVLO Overall Section Inactive Supply Current Active Supply Current Clamp Voltage Turn-On Threshold Turn-Off Threshold Threshold Hysteresis ICC=25mA VCC=10V 14.5 10.5 16.3 11.5 10.0 17.5 13.0 VCC=13V, IOUT= -200mA, RAMP=2V IOUT=200mA, ISNS= -1.0V IOUT=10mA, ISNS= -1.0V IOUT= -200mA, RAMP=2V IOUT=100mA, VCC=0V 10.0 0.05 12.0 0.40 14.5 COMP=7.5V COMP=2.5V VFB=0.0V, COMP open -5.00 -300 -175 10.0 -100 10.6 -0.03 5.00 -550 -100 -450 -350 RAMP=2.5V ISNS= -1.0V, RAMP=1.0V ISNS= -1.0V, IRAMP=100µA VFB=10V, COMP open 0.92 0.006 1.02 0.200 1.12 TEST CONDITIONS MIN. TYP. MAX. UNITS
DETAILED BLOCK DIAGRAM
UC1852 UC2852 UC3852
UDG-92003
DESCRIPTIONS
COMP: COMP output error amplifier input comparator. limit on-time, this clamped approximately 10V. implement soft start, COMP pulled ramped with transistor, capacitor, resistor. GND: Ground functions through this pin. ISET: dominant function this program RAMP charging current. RAMP charging current approximately divided external resistor placed from ISET ground. Resistors range recommended, producing currents range 100µA 500µA. second function ISET reference output. ISET normally regulated ±10%. critical that this only loading RAMP programming resistor, high input-impedance comparator amplifier connected this RAMP programming resistor required. third function ISET FAULT output. event over-current fault, ISET forced approximately fault comparator. This used trip external protection circuit which disable load start fault restart cycle. ISNS: This input zero over current comparators specially built allow operation over dynamic range. noisy systems systems with very high inductors, desirable filter signal entering ISNS input prevent premature restart fault cycles. best accuracy, ISNS should connected current sense resistor through more than ohms. OUT: output high-current power driver capable driving gate power MOSFET with peak currents exceeding ±500mA. prevent damage power MOSFET, internally driven supply. However, lead inductance between load cause overshoot ringing. External current boost transistors will increase this overshoot ringing. there significant distance between MOSFET, external clamp diodes and/or series damping resistors required. actively held when below UVLO threshold. RAMP: controlled on-time requires timer whose time modulated external voltage. timer current programmed resistor from ISET GND. capacitor from RAMP sets time conjunction with voltage COMP. Recommended values timer capacitors between 100pF 1nF. VCC: logic control power connection this device. current active device supply current average current. Knowing maximum operating frequency MOSFET gate charge (Qg), average current estimated IOUT prevent noise problems, bypass with both ceramic electrolytic capacitor. VFB: error amplifier inverting input. This input serves both voltage sense input error amplifier
TYPICAL CHARACTERISTICS
UC1852 UC2852 UC3852
Error Amplifier Gain Phase Gain (dB) Phase (deg) 1000 10000
UDG-92005
Frequency Rset 1000 100pF 500pF
Phase
Gain
Maximum Frequency,
Rset,
UDG-92006
Frequency,
On-Time Rset 1000
Rise Fall Time
Fall Time
Maximum On-Time
10nF
Rise Time
300pF 100pF
Rset,
UDG-92007
Load Capacitance,
UDG-92008
APPLICATION INFORMATION: Watt Power Factor Preregulator
UC1852 UC2852 UC3852
UDG-92004
This circuit demonstrates complete power factor preregulator based UC3852. This preregulator will supply watts 400VDC exhibit power factor greater than 0.995 with less than total harmonic distortion. Operating input range 160V 50Hz 60Hz. This design intentionally simple, fully functional. UC3852 also used designs featuring soft start, over-voltage protection, wide power-line voltage operation, fault latching. more information applying UC3852, refer Unitrode Application Note U-132. PARTS LIST
0.47µF/250VAC Class Polyester 1nF/16V Ceramic 68µF/35V Aluminum Electrolytic 180pF/16V Ceramic 0.1µF/16V Polyester Ceramic 82µF/450V Aluminum Electrolytic 2A/500V Bridge Rectifier (Collmer KBPC106 Powertex MB11A02V60) 100mA/50V Switching Diode (1N4148) 2A/500V 250ns Recovery-Time Rectifier (Motorola MR856) UC3852N Power Factor Controller IRF830 4.5A/500V Power 680µH (Renco RL3792 with Turn Secondary) 150k, 1/4W 0.2, 1/2W Carbon Composition 1/4W 13.3k, 1/4W 1/4W 20k, 1/4W 200k, 1/2W 200k, 1/2W
UNITRODE INTEGRATED CIRCUITS CONTINENTAL BLVD. MERRIMACK, 03054 TEL. (603) 424-2410 (603) 424-3460
IMPORTANT NOTICE Texas Instruments subsidiaries (TI) reserve right make changes their products discontinue product service without notice, advise customers obtain latest version relevant information verify, before placing orders, that information being relied current complete. products sold subject terms conditions sale supplied time order acknowledgement, including those pertaining warranty, patent infringement, limitation liability. warrants performance semiconductor products specifications applicable time sale accordance with TI's standard warranty. Testing other quality control techniques utilized extent deems necessary support this warranty. Specific testing parameters each device necessarily performed, except those mandated government requirements. CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS INVOLVE POTENTIAL RISKS DEATH, PERSONAL INJURY, SEVERE PROPERTY ENVIRONMENTAL DAMAGE ("CRITICAL APPLICATIONS"). SEMICONDUCTOR PRODUCTS DESIGNED, AUTHORIZED, WARRANTED SUITABLE LIFE-SUPPORT DEVICES SYSTEMS OTHER CRITICAL APPLICATIONS. INCLUSION PRODUCTS SUCH APPLICATIONS UNDERSTOOD FULLY CUSTOMER'S RISK. order minimize risks associated with customer's applications, adequate design operating safeguards must provided customer minimize inherent procedural hazards. assumes liability applications assistance customer product design. does warrant represent that license, either express implied, granted under patent right, copyright, mask work right, other intellectual property right covering relating combination, machine, process which such semiconductor products services might used. TI's publication information regarding third party's products services does constitute TI's approval, warranty endorsement thereof.
Copyright 1999, Texas Instruments Incorporated

UC1852 UC2852 UC3852

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