UNISONIC TECHNOLOGIES CO., LTD UC3842B/3843B LINEAR INTEGRATED CIRCUIT HIGH PERFORMANCE CURRENT MODE CONTROLLERS DESCRIPTION The UTC UC3842B/3843B are specifically designed for off-line and dc-to-dc converter applications offering the designer a cost-effective solution with minimal external components. The UC3842B has UVLO thresholds 16V (on) and 10V(off), ideally suited for off-line converters. The UC3843B is tailored for lower voltage applications having UVLO thresholds of 8.4V(on) and 7.6V(off). FEATURES * Trimmed oscillator for precise frequency control * Oscillator frequency guaranteed at 250kHz * Current mode operation to 500kHz * Automatic feed forward compensation * Latching PWM for cycle-by-cycle current limiting * Internally trimmed reference with undervoltage lockout * High current totem pole output * Undervoltage lockout with hysteresis * Low startup and operating current ORDERING INFORMATION Ordering Number Lead Free Halogen Free UC3842BL-D08-T UC3842BP-D08-T UC3842BP-S08-R UC3843BL-D08-T UC3843BP-D08-T UC3843BP-S08-R www.unisonic.com.tw Copyright © 2015 Unisonic Technologies Co., Ltd Package Packing DIP-8 SOP-8 DIP-8 SOP-8 Tube Tape Reel Tube Tape Reel 1 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT MARKING Package UC3842B UC3843B 8 7 6 5 UTC UC3843B DIP-8 1 2 3 4 Date Code L: Lead Free P: Halogen Free Lot Code SOP-8 PIN CONFIGURATION COMP 1 8 VREF VFB 2 7 VCC CS 3 6 OUTPUT RTCT 4 5 GND PIN DESCRIPTIONS PIN NO. 1 PIN NAME COMP I/O O 2 VFB I 3 4 5 6 7 8 CS RTCT GND OUTPUT VCC VREF I I O O DESCRIPTION Error amp output to provide loop compensation maintaing VFB at 2.5V Error amp inverting input, The non-inverting input of error amp is 2.5V band gap reference Current sense input to PWM control gate drive of output To set oscillator frequency and maximum output duty cycle Power ground To direct drive power MOSFET Power supply 5V regulated output provides charging current for CT through RT UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT BLOCK DIAGRAM UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT ABSOLUTE MAXIMUM RATINGS(TA=25°C, unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT Total Power Supply and Zener Current (ICC + IZ) 30 mA Output Current, Source or Sink (Note 2) IO 1.0 A Output Energy (capacitive load per cycle) W 5.0 μJ Current Sense and Voltage Feedback Inputs VIN -0.3 ~ +5.5 V Error Amp. Output Sink Current IO(SINK) 10 mA DIP-8 1250 mW Power Dissipation PD SOP-8 800 mW Operating Junction Temperature TJ +150 °C Operating Temperature TOPR 0 ~ +70 °C Storage Temperature TSTG -65 ~ +150 °C Notes: 1. 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. 2. Maximum Package power dissipation limits must be observed. THERMAL DATA PARAMETER Junction to Ambient SYMBOL DIP-8 SOP-8 θJA RATINGS 100 156 UNIT C/W C/W ELECTRICAL CHARACTERISTICS (0°C ≤TA≤70°C, VCC=15V (Note 1), RT=10k, CT=3.3nF, unless otherwise specified) PARAMETER SYMBOL TEST CONDITIONS REFERENCE SECTION Output Voltage VREF IO=1.0mA, TJ =25°C Line Regulation ∆VLINE VCC=12V ~ 25V Load Regulation ∆VLOAD IO=1.0mA ~ 20mA Temperature Stability TS Total Output Variation VREF Line, Load, Temperature Output Noise Voltage eN F=10kHz ~ 10Hz, TJ =25°C Long Term Stability S TA=125°C,1000Hrs Output Short Circuit Current ISC OSCILLATOR SECTION TJ =25°C Frequency F TA=0°C ~ 70°C TJ =25°C (RT=6.2k,CT=1.0nF) Frequency Change with Voltage fOSC/V 12 ≤ VCC ≤25V Frequency Change with fOSC/T 0°C ≤TA ≤70°C Temperature Oscillator Voltage Swing VOSC (Peak to Peak) TJ =25°C Discharge Current IDISCHG 0°C ≤TA ≤70°C UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MIN TYP MAX UNIT 4.9 5.0 2.0 3.0 0.2 5.1 20 25 V mV mV mV/°C V μV mV mA 4.82 -30 49 48 225 7.8 7.6 5.18 50 5 -85 52 250 0.2 -180 55 56 275 1.0 kHz % 0.5 % 1.6 V 8.3 8.3 8.8 8.8 mA 4 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT ELECTRICAL CHARACTERISTICS (Cont.) PARAMETER ERROR AMPLIFIER SECTION Voltage Feedback Input Input Bias Current Open Loop Voltage Gain Unity Gain Bandwidth Power Supply Rejection Ratio Output Sink Current Output Source Current Output Voltage Swing High State Output Voltage Swing Low State CURRENT SENSE SECTION Current Sense Input Voltage Gain Maximum Current Sense Input Threshold Power Supply Rejection Ratio Input Bias Current Propagation Delay OUTPUT SECTION SYMBOL MIN TYP MAX UNIT Vo=2.5V VFB=5.0V 2 ≤VO≤4V TJ =25°C I2V≤VCC≤25V VO=1.1V,VFB =2.7V VO=5.0V,VFB=2.3V VFB=2.3V, RL=15k to GND VFB=2.7V, RL=15k to VREF 2.42 2.50 -0.1 90 1.0 70 12 -1.0 6.2 0.8 2.58 -2.0 1.1 V μA dB MHz dB mA mA V V (Note 2, 3) 2.85 3.0 3.15 V/V VI(THR) (Note 2) 0.9 1.0 1.1 V PSRR II(BIAS) 12≤Vcc≤25V (Note 2) Current Sense Input to Output 70 -2 150 -10 300 dB μA ns ISINK=20mA ISINK=200mA ISOURCE=20mA ISOURCE=200mA 0.1 1.6 13.5 13.4 0.4 2.2 V V V V VCC=6.0V,ISINK=1.0mA 0.1 1.1 V TJ =25°C, CL=1nF TJ =25°C, CL=1nF 50 50 150 150 ns ns 14.5 7.8 8.5 7.0 16 8.4 10 7.6 17.5 9 11.5 8.2 V V V V 94 96 0 % % 0.3 0.5 mA 12 36 17 mA V VFB II(BIAS) GVO GBW PSRR ISINK ISOURCE VOH VOL GV tD(IN/OUT) Output Low Voltage VOL Output High Voltage VOH Output Voltage with UVLO VOL (UVLO) Activated Output Voltage Rise Time tR Output Voltage Fall Time tF UNDER-VOLTAGE LOCKOUT SECTION Startup Threshold Min. Operating Voltage After Turn-on(VCC) PWM SECTION MAX Duty Cycle MIN Total DEVICE VTHR VCC(MIN) TEST CONDITIONS UC3842B UC3843B UC3842B UC3843B DC VCC=6.5V for UC3843B VCC=14V for UC3842B Power Operating Supply Current ICC+IC Note 1 Power Supply Zener Voltage VZ ICC=25mA Note: 1. Adject VCC above the Startup threshold before setting to 15V. 2. This parameter is measured at the latch trip point with VFB=0V. V Output Compensation 3. Comparator gain is defined as : GV V Current Sense Input Power Startup Supply Current 13 12 ICC+IC UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 65 0.7 60 2.0 -0.5 5.0 30 5 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT TYPICAL APPLICATION CIRCUIT Open Loop Test Circuit All of the parameters are not all tested in production, although been guaranteed. The timing and bypass capacitors must be connected to Pin 5 in a single point ground very closely. To sample the oscillator waveform, the transistor and 5kΩ potentiometer are used, and also can apply an adjustable ramp to ISENSE Pin. 2N 2222 RT 100K E/A ADJUST 4.7K 3 ISENSE 1K ISENSE ADJUST 1 COMP 2 VFB 4.7K VREF UTC UC3842B/3843B VREF 8 A VC 7 V1 OUTPUT OUTPUT 6 0.1 5K 4 RT/CT CT GND 5 0.1 1K/1W Under Voltage Lockout Under-Voltage Lock-Out: the output driver is biased to a high impedance state. To prevent activating the power switch with output leakage current, Pin 6 should be shunted to ground with a bleeder resistor. Error Amp Configuration UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) Current Sense Circuit Peak current (IS) is equaled: IS(MAX)=1.0V/RS There should be a small RC filter to suppress switch transients. Oscillator Waveforms and Maximum Duty Cycle VREF 8 RT/RC 4 LARGE RT SMALL CT V4 RT INTERINAL CLOCK CT GND SMALL CT LARGE RT 5 V4 INTERINAL CLOCK CT (Oscillator timing capacitor) can be charged by VREF through RT and discharged by an internal current source. At discharge time, the internal clock signal blanks the output to the low. Both oscillator frequency and maximum duty cycle can be determined by Selection of RT and CT. All charge and discharge times can be calculated by the next formulas: tC=0.55 RT CT 0.0063R T 2.7 tD=RTCTIN 0.0063R T 4 UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT APPLICATION INFORMATION(Cont.) Shutdown Techniques 1KΩ 8 VREF 3 ISENSE 1 COMP SHUTDOWN 330Ω SHUTDOWN 500Ω (Deadtime vs CT RT > 5kΩ) TO CURRENT SENSE-RESISTOR The UTC UC3842B’s shutdown can be accomplished by two ways: raise Pin 3 above 1V; or pull Pin 1 below a voltage two diode drops above ground. Either method can cause the PWM comparator’s output to be high. Because the PWM latch is reset dominant, the output will remain low until the next clock cycle after the shutdown condition at Pins 1 and/or 3 is removed. Slope Compensation UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 8 of 11 QW-R103-012.F UC3842B/3843B Percent Output Deadtime, %DT. 0 =2 CT F 0p nF .0 =5 CT 0 =1 CT Maximum Output Duty Cycle, Dmax (%) nF .0 =1 CT nF Timing Resistor, RT (KΩ) TYPICAL CHARACTERISTICS 20mV/DIV Discharge Current, Idischg (mA) LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 9 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT TYPICAL CHARACTERISTICS(Cont.) UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 10 of 11 QW-R103-012.F UC3842B/3843B LINEAR INTEGRATED CIRCUIT TYPICAL CHARACTERISTICS(Cont.) Fig. 13 Output Saturation Voltage Versus Load Current Source Saturation (Load to Ground) VCC TA=25°C -10 -20 VCC=15V CL=1.0nF TA=25°C 90 % TA=-55°C 10 Sink Saturation (Load to VCC) 10 % GND 200 400 600 Output Load Current, IOUT (mA) 800 50ns/DIV Fig. 16 Supply Current vs. Supply Voltage Fig. 15 Output Cross Conduction 25 VCC=30V CL=15pF TA=25°C 100mA/DIV Supply Current, ICC Output Voltage, VO 0 TA=25° C 20 15 10 UC3843B 20 TA=55°C Supply Current, ICC (mA) 30 0 VCC=15V 80µs Pulsed Load 120Hz Rate 20V/DIV Output Saturation Voltage, VSAT (V) 0 Fig. 14 Output Waveform 5 0 0 RT=10k CT=3.3nF VFB=0V ISENSE=0V TA=25°C UC3842B 10 20 30 40 Supply Voltage, VCC (V) 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 11 of 11 QW-R103-012.F