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UC1842A Dataheets PDF



Part Number UC1842A
Manufacturers LINFINITY
Logo LINFINITY
Description CURRENT MODE PWM CONTROLLER
Datasheet UC1842A DatasheetUC1842A Datasheet (PDF)

T H E I N F I N I T E P O W E R O F I N N O VAT I O N L I N D O C #: 1840 UC184xA/284xA/384xA CURRENT MODE PWM CONTROLLER PR O D U C T I O N D ATA S H E E T DESCRIPTION The UC184xA family of control ICs provides all the necessary features to implement off-line fixed-frequency, current-mode switching power supplies with a minimum of external components. The current mode architecture demonstrates improved load regulation, pulse-by-pulse current limiting and inherent protection of the power supp.

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T H E I N F I N I T E P O W E R O F I N N O VAT I O N L I N D O C #: 1840 UC184xA/284xA/384xA CURRENT MODE PWM CONTROLLER PR O D U C T I O N D ATA S H E E T DESCRIPTION The UC184xA family of control ICs provides all the necessary features to implement off-line fixed-frequency, current-mode switching power supplies with a minimum of external components. The current mode architecture demonstrates improved load regulation, pulse-by-pulse current limiting and inherent protection of the power supply output switch. The IC includes: A bandgap reference trimmed to ±1% accuracy, an error amplifier, a current sense comparator with internal clamp to 1V, a high current totem pole output stage for fast switching of power MOSFET's, and an externally programmable oscillator to set frequency and maximum duty cycle. The undervoltage lock-out is designed to operate with 250µA typ. start-up current, allowing an efficient bootstrap supply voltage design. Available options for this family of products, such as start-up voltage hysteresis and duty cycle, are summarized below in the Available Options section. The UC184xA family of control ICs is also available in 14-pin SOIC package which makes the Power Output Stage Collector and Ground pins available. PRODUCT HIGHLIGHT COMPARISON OF UC384XA VS. SG384 X DISCHARGE CURRENT SG384x Min. Limit UC384xA TA=25°C SG384x Max. Limit KEY FEATURES s LOW START-UP CURRENT. (0.5mA max.) s TRIMMED OSCILLATOR DISCHARGE CURRENT. (See Product Highlight) p OPTIMIZED FOR OFF-LINE AND DC-TO-DC CONVERTERS. p AUTOMATIC FEED FORWARD COMPENSATION. p PULSE-BY-PULSE CURRENT LIMITING. p ENHANCED LOAD RESPONSE CHARACTERISTICS. p UNDER-VOLTAGE LOCKOUT WITH HYSTERESIS. p DOUBLE PULSE SUPPRESSION. p HIGH-CURRENT TOTEM POLE OUTPUT. p INTERNALLY TRIMMED BANDGAP REFERENCE. p 500KHz OPERATION. p LOW RO ERROR AMPLIFIER. A P P L I C AT I O N S s ECONOMICAL OFF-LINE FLYBACK OR FORWARD CONVERTERS. s DC-DC BUCK OR BOOST CONVERTERS. s LOW COST DC MOTOR CONTROL. 7.5 7.8 −3σ 8.3 Mean 8.8 9.3 +3σ Discharge Current Distribution - mA AVAILABLE OPTIONS Part # Start-Up Hysteresis Max. Duty Voltage Cycle UCx842A 16V 6V <100% UCx843A 8.4V 0.8V <100% UCx844A 16V 6V <50% UCx845A 8.4V 0.8V <50% TA (°C) PACKAGE ORDER INFORMATION M Plastic DIP 8-pin DM Plastic 8-pin SOIC D Plastic SOIC 14-pin Y Ceramic DIP 8-pin 0 to 70 -40 to 85 -55 to 125 UC384xAM UC284xAM — UC384xADM UC284xADM — UC384xAD UC284xAD — — UC284xAY UC184xAY Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (i.e. UC3842ADMT) Copyright © 1995 Rev. 1.2 12/95 FOR FURTHER INFORMATION CALL (714) 898-8121 11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841 1 PRODUCT DATABOOK 1996/1997 UC184xA/284xA/384xA CURRENT MODE PWM CONTROLLER PRODUCTION DATA SHEET A B S O L U T E M A X I M U M R AT I N G S (Note 1) Supply Voltage (Low Impedance Source) (VCC) ......................................................... 30V Supply Voltage (ICC < 30mA) .......................................................................... Self Limiting Output Current ............................................................................................................. ±1A Output Energy (Capacitive Load) ................................................................................. 5µJ Analog Inputs (VFB & ISENSE) ........................................................................ -0.3V to +6.3V Error Amp Output Sink Current ............................................................................... 10mA Power Dissipation at TA = 25°C (M Package) .............................................................. 1W Storage Temperature Range .................................................................... -65°C to +150°C Lead Temperature (Soldering, 10 Seconds) ............................................................. 300°C Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. Pin numbers refer to DIL packages only. T H E R MAL DATA M PACKAGE: THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA DM PACKAGE: 95°C/W THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA D PACKAGE: 165°C/W THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA Y PACKAGE: 120°C/W THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA 130°C/W Junction Temperature Calculation: TJ = TA + (PD x θJA). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow PACKAGE PIN OUTS COMP VFB ISENSE RT/CT 1 2 3 4 8 VREF 7 VCC 6 OUTPUT 5 GND M & Y PACKAGE (Top View) COMP VFB ISENSE RT/CT 1 8 VREF 2 7 VCC 3 6 OUTPUT 4 5 GND DM PACKAGE (Top View) COMP N.C. VFB N.C. ISENSE N.C. RT/CT 1 14 VREF 2 13 N.C. 3 12 VCC 4 11 VC 5 10 OUTPUT 6 9 GND 7 8 PWR GND D PACKAGE (Top View) 2 Copyright © 1995 Rev. 1.2 12/95 PRODUCT DATABOOK 1996/1997.


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