CORPORATION GSC3843 ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C HIGH PERFORMANCE CURRENT MODE CONTROLERS Description The GSC3843 is specifically designed for Off-Line and dc-to-dc converter applications offering the designer a cost-effective solution with minimal external components. The GSC3843 has UVLO thresholds 8.5V (on) and 7.6V (off), ideally suited for off-line converters. 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 Package Dimensions Millimeter Min. Max. REF. A B C D E F SOP-8L 5.80 4.80 3.80 0° 0.40 0.19 Function Pin1:Compensation Pin2:Voltage Feedback Pin3:Current Sense Pin4:RT/CT Pin5:Ground Pin6:Output Pin7:Vcc Pin8:Vref 6.20 5.00 4.00 8° 0.90 0.25 REF. Millimeter Min. Max. M H L J K G 0.10 0.25 0.35 0.49 1.35 1.75 0.375 REF. 45° 1.27 TYP. Description This pin is the Error Amplifier output and is made available for loop compensation. This is the inverting input of the Error Amplifier. It’s normally connected to the Switching power supply output through a resistor divider. A voltage proportional to inductor current is connected to this input .The PWM uses this information to terminate the output switch conduction. The oscillator frequency and maximum output duty cycle are programmed by connecting resistor RT to Vref and capacitor CT to ground .Operation 500kHz is possible. This pin is the combined control circuitry and power ground. This output directly drives the gate of a power MOSFET. Peak currents up to 1 A are sourced and sunk by this pin. This pin is the positive supply of the control IC. This is the reference output .It provides charging current for capacitor CT through resistor RT. Absolute Maximum Ratings at Ta = 25 Symbol Value Unit Total power Supply and Zener current Parameter (ICC+Iz) 30 mA Output current, source or sink(note1) Io 1.0 A Output energy(capacitive load per cycle) W 5.0 J Current sense and voltage feedback inputs Vin -0.3 to 5.5 V Io 10 mA Error Amplifier Output Sink Current GSC3843 Page: 1/9 CORPORATION Power Dissipation at Thermal Characteristics PD P JA 1250 100 Storage Temperature Range mW /W Tstg -65 to 150 Operating Junction Temperature TJ +150 Operating ambient Temperature TA 0~+70 Electrical Characteristics (0 TA 70 Parameter ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C , Vcc=15V [note 2], R T=10k, C T=3.3nF, unless otherwise specified) Symbol Test Conditions Min Typ Max Unit Reference Section Output Voltage VREF Tj=25 4.90 5 5.1 V Line Regulation Regline Vcc=12V to 25V - 2.0 20 mV Load Regulation Regload Io=1mA to 20mA - 3.0 25 mV Temperature. Stability Ts - - 0.2 - Total Output Variation VREF Line, Load, Temperature 4.82 - 5.18 Output Noise Voltage Vn F=10kHz to 10Hz,Tj=25 - 50 - V Long Term Stability S TA=125 - 5 - mV Output Short Circuit current ISC - -30 -85 -180 mA Tj=25 49 52 55 Oscillator Section Frequency Frequency Change with Voltage Frequency Change with Temperature Oscillator Voltage Swing(Peak to Peak) Discharge Current ,Io=1mA ,1000Hrs TA=0 to 70 Tj=25 (RT =6.2k,CT =1.0nF) 48 - 56 225 250 275 mV/ V KHz fosc/ V Vcc=12V to 25V - 0.2 1.0 % fosc/ T TA = 0 - 0.5 - % - 1.6 - V 7.8 7.6 8.3 - 8.8 8.8 mA V VOSC - Idischg Tj=25 TA = 0 to 70 to 70 Error Amplifier Section Voltage Feedback Input VFB Vo =2.5V 2.42 2.50 2.58 Input Bias Current IIB VFB=5.0V - -0.1 -2.0 Open Loop Voltage Gain AVOL Vo=2V to 4V 65 90 - dB Unity Gain Bandwidth BW Tj=25 0.7 1.0 - MHz Power Supply Rejection Ratio PSRR Vcc=12V to 25V 60 70 - dB Output Sink Current Isink Vo=1.1V,VFB=2.7V 2.0 12 - mA Output Source Current Isource Vo=5.0V,VFB=2.3V -0.5 -1.0 - mA Output Voltage Swing High State VoH VFB=2.3V,RL =15K to GND 5.0 6.2 - V Output Voltage Swing Low State VOL VFB=2.7V,RL =15K to Vref - 0.8 1.1 V Av (Note 3,4) 2.85 3.0 3.15 V/V Maximum Current Sense Input Threshold Vth (Note 3) 0.9 1.0 1.1 V Power Supply Rejection Ratio PSRR VCC= 12 to 25V (Note 3) - 70 - dB Input Bias Current IIB - - -2 -10 A Propagation Delay Tplh(in/out) Current Sense Input to Output VOL Isink=20mA - 150 300 ns - 0.1 0.4 V - 1.6 2.2 V Isource=20mA 13 13.5 - V Isource=200mA 12 13.4 - V VCC=6.0V,Isink=1.0mA - 0.1 1.1 V A Current Sense section Current Sense Input Voltage gain Output Low Voltage Output High Level Output Voltage with UVLO Activated Isink=200mA VOH VOL (UVLO) Output Voltage Rise Time tr Tj=25 ,CL=1nF - 50 150 ns Output Voltage Fall Time tr Tj=25 ,CL=1nF - 50 150 ns Vth - 7.8 8.4 9.0 V - 7.0 7.6 8.2 V Under-Voltage Lockout Section Startup Threshold Min. Operating Voltage After Turn-on(VCC) VCC(min) GSC3843 Page: 2/9 CORPORATION ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C PWM Section Maximum Duty Cycle DC(MAX) - 94 96 - % Minimum Duty Cycle DC(MIN) - - - 0 % ICC+IC VCC=14V - 0.2 0.3 mA Power Operating Supply Current ICC+IC Note 2 - 12 17 mA Power Supply Zener Voltage Vz ICC=25mA 30 36 - V Total Device Power Startup Supply Current Note 1: Maximum Package power dissipation limits must be observed. Note 2: Adject Vcc above the Startup threshold before setting to 15V. Note 3: This parameter is measured at the latch trip point with VFB=0V. Note 4: Comparator gain is defined as:: AV V Output Compensation V Current Sense Input Characteristics Curve GSC3843 Page: 3/9 CORPORATION GSC3843 ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C Page: 4/9 CORPORATION GSC3843 ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C Page: 5/9 CORPORATION ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C Application Information GSC3843 Page: 6/9 CORPORATION GSC3843 ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C Page: 7/9 CORPORATION GSC3843 ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C Page: 8/9 CORPORATION ISSUED DATE :2004/04/19 REVISED DATE :2005/10/05C Important Notice: All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of GTM. GTM reserves the right to make changes to its products without notice. GTM semiconductor products are not warranted to be suitable for use in life-support Applications, or systems. GTM assumes no liability for any consequence of customer product design, infringement of patents, or application assistance. Head Office And Factory: Taiwan: No. 17-1 Tatung Rd. Fu Kou Hsin-Chu Industrial Park, Hsin-Chu, Taiwan, R. O. C. TEL : 886-3-597-7061 FAX : 886-3-597-9220, 597-0785 China: (201203) No.255, Jang-Jiang Tsai-Lueng RD. , Pu-Dung-Hsin District, Shang-Hai City, China TEL : 86-21-5895-7671 ~ 4 FAX : 86-21-38950165 GSC3843 Page: 9/9