UNISONIC TECHNOLOGIES CO., LTD UC3842G LINEAR INTEGRATED CIRCUIT HIGH PERFORMANCE CURRENT MODE CONTROLLER ■ DESCRIPTION The UTC UC3842G of high performance current mode controller is specifically designed for off-line and DC-to-DC converter applications offering the designer a cost effective solution with minimal external components. This integrated circuit features approximately 300μA start up current, a precision reference trimmed the error amplifier input. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle-by-cycle current limiting, and so on. ■ FEATURES Lead-free: UC3842GL Halogen-free: UC3842GP * Low startup and operating current * User defined switching frequency(Norm is 52kHz) * Power-saving mode for low power * Under voltage lockout with hysteresis * Over voltage protection * Latching PWM for Cycle-By-Cycle current limiting * Internally trimmed reference with undervoltage lockout ORDERING INFORMATION Normal UC3842G-S08-R UC3842G-S08-T UC3842G-D08-T Ordering Number Lead Free UC3842GL-S08-R UC3842GL-S08-T UC3842GL-D08-T www.unisonic.com.tw Copyright © 2008 Unisonic Technologies Co., Ltd Halogen Free UC3842GP-S08-R UC3842GP-S08-T UC3842GP-D08-T Package Packing SOP-8 SOP-8 DIP-8 Tape Reel Tube Tube 1 of 8 QW-R103-036.B UC3842G LINEAR INTEGRATED CIRCUIT PIN CONFIGURATION COMP 1 ■ 8 VREF FB 2 7 VCC CS 3 6 OUT CT 4 5 GND PIN DESCRIPTION PIN NO. 1 2 3 4 5 6 7 8 PIN NAME COMP FB CS CT GND OUT VCC VREF I/O O I I I O O Function This pin is error amplifier output The error amplifier inverting input Current sense input The capacitor controlling switch frequency Ground Output to the gate of external power MOS Supply voltage Inter 5V reference voltage output UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 8 QW-R103-036.B UC3842G ■ LINEAR INTEGRATED CIRCUIT BLOCK DIAGRAM UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 8 QW-R103-036.B UC3842G LINEAR INTEGRATED CIRCUIT ABSOLUTE MAXIMUM RATINGS (Ta＝25°C) PARAMETER SYMBOL RATINGS UNIT Supply Voltage (Low Impedance Source) VCC 30 V Supply Voltage (ICC<30mA) VCC Self Limiting V Output Current (Peak) IO(PEAK) ±1 A Output Energy (Capacity load) 5 μJ Junction Temperature TJ +150 °C Operating Temperature TOPR -40 ~ +125 °C Storage Temperature TSTG -65 ~ +150 °C Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. ELECTRICAL CHARACTERISTICS (0°C≤Ta≤70°C, VCC=15V, CT=3.3nF , unless otherwise specified) PARAMETER SYMBOL TEST CONDITION STANDBY SECTION Reduce Frequency Point of Standby Mode VCOMP Right load REFERENCE SECTION Reference Output Voltage VREF IOUT=1.0mA Line Regulation ΔVREF 12V≤VCC≤25V Load Regulation ΔVREF IOUT=1.0mA to 20mA Output Short Circuit Current ISC OSCILLATOR SECTION Frequency fOSC Normal Frequency Change ΔfOSC/ΔV 12V≤VCC≤25V VOSC(P-P) Oscillator Voltage VOSCL VOSCH ERROR AMPLIFIER SECTION Input Voltage VI(EA) VCOMP=2.5V Input Bias Current II(BIAS) VFB=5V AVOL 2V≤VOUT≤4V Unity Gain Bandwidth TJ=25°C(Note1) PSRR 12V≤VCC≤25V Output Sink Current ISINK VFB=2.7V, VCOMP=1.1V Output Source Current ISOURCE VFB=2.3V, VCOMP=5V VOUT High VOH VFB=2.3V, RL=15K to GND VOUT Low VOL VFB=2.7V, RL=15K to VREF CURRENT SENSE SECTION Gain GV (Note2,3) Maximum Input Signal VI(MAX) VCOMP=5V(Note2) PSRR 12V≤VCC≤25V Input Bias Current IBIAS Delay to Output UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MIN TYP MAX 2.2 4.95 -30 49 2.42 60 0.7 60 2 -0.5 5.0 2.85 0.9 UNIT V 5.0 3 8 -65 5.05 20 25 -180 V mV mV mA 52 0.2 1.6 1.2 2.8 55 1.0 KHz ％ 2.50 -0.3 90 1 70 4 1 5.6 0.8 2.58 -2 3 1 70 -2 150 3.15 1.1 V V V 1.1 -10 300 V μA dB MHz dB mA mA V V V/V V dB μA nS 4 of 8 QW-R103-036.B UC3842G LINEAR INTEGRATED CIRCUIT ELECTRICAL CHARACTERISTICS (Cont.) PARAMETER OUTPUT SECTION SYMBOL Output Voltage With UVLO Active VOL(UVLO) VOL Output Voltage VOH Output Voltage Rise and Fall time tR tF TEST CONDITION VCC=6V,ISINK=0.1mA; VCC=7.5V,ISINK=1mA ISINK=20mA ISINK=200mA ISOURCE=20mA ISOURCE=200mA CL=1.0nF(Note1) CL=1.0nF(Note1) UNDER VOLTAGE LOCKOUT SECTION Startup Threshold VTH(STAR-UP) Min Operating Voltage VOPR(MIN) After Turn-ON PWM SECTION Max Duty Cycle DMAX Minimum Duty Cycle DMIN TOTAL DEVICE Power Supply Zener Voltage VZ ICC=25mA Power Operating Supply Current ICC Note2 Startup Current ISTART-UP VCC=14V,UVLO Active Note: 1. These parameters, although guaranteed, are not 100% tested in production. 2. Parameters measured at trip point of latch with VFB=0. 3. Gain defined as: A=ΔVCOMP/ΔVCS; 0≤VCS≤0.8V UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MIN TYP MAX UNIT 0.8 1.1 V 0.1 1.6 14.5 14.6 100 100 0.4 2.2 V V V V 150 150 nS 13.5 8.5 15 10 16.5 11.5 V V 92 94 0 % % 10 40 V mA μA 13 12 30 39 7 15 5 of 8 QW-R103-036.B UC3842G LINEAR INTEGRATED CIRCUIT OPEN-LOOP TEST CIRCUIT VCOMP VIN Ra 100k Rb 100k VREF 8 10p VFB or 1 COMP 2 FB VCC 7 VCC Vpwl adjust 3 CS Output 6 4 CT GND 5 CIN 470μ 5K CT 3.3n High peak current associated with capacity loads necessitate careful grounding techniques. Timing and bypass capacitors should be connected close to pin5 in single point GND. UNDER-VOLTAGE LOCKOUT During Under-Voltage Lockout, the output driver is biased to a high impedance state. Pin6 should be shunt to GND with a bleeder resistor to prevent activing the power switch with output leakage currents. ERROR AMPLIFIER CONFIGURATION Error amplifier can source or sink up to 0.5mA UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 8 QW-R103-036.B UC3842G LINEAR INTEGRATED CIRCUIT CURRENT SENSE CIRCUIT Error Amplifier 2R Is 1 R Rs C 3 R 1V Current Sense Comparator 5 Peak current (IS) determined by the formula: ISMAX=1V/Rs. A small RC filter be required to suppress switch transients OSCILLATOR AND STANDBY MODE We can judge the state of output load through the voltage of PIN1. In order to reduce the standby power, it will reduce the OSC frequency at right load. When VCOMP≤2.2V, the OSC frequency begins to reduce. The normal frequency is 52KHz, the minimum frequency is 14KHz. VCOMP 2.2V Increase 1.2V Normal Frequency: 52KHz Standby mode Minimum frequency :14KHz Normal Frequency: 52KHz OSC triangle wave UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 8 QW-R103-036.B UC3842G LINEAR INTEGRATED CIRCUIT SHUTDOWN TECHNIQUE 1kΩ Shutdown 330Ω 3 500Ω Shutdown 1 8 To current Sense resistor Shutdown UTC UC3842G can be accomplished by two methods; either raise pin 3 above 1V or pull Pin 1 below a voltage two diode drops above ground. UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 8 of 8 QW-R103-036.B