Product Specification SG6742 Highly Integrated Green-Mode PWM Controller FEATURES High-voltage start-up Low operating current (4mA) Linearly decreasing PWM frequency to 22KHz Frequency jittering to reduce EMI emission Fixed PWM frequency (65KHz) Peak-current-mode control Cycle-by-cycle current limiting Leading-edge blanking Synchronized slope compensation Internal open-loop protection GATE output maximum voltage clamp (18V) VDD under-voltage lockout (UVLO) VDD over voltage protection (OVP) Programmable over-temperature protection (RT) Internal latch circuit (OVP, RT) Constant power limit (full AC input range) Internal OTP sensor with hysteresis APPLICATIONS General-purpose switch-mode power flyback power converters, including: supplies and Power Adapters Open-Frame SMPS DESCRIPTION To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency at light-load conditions. To avoid acoustic noise problems, the minimum PWM frequency is set above 22KHz. This green-mode function enables the power supply to meet international power conservation requirements. With the internal high-voltage start-up circuitry, the power loss due to bleeding resistors is eliminated. To further reduce power consumption, SG6742 is manufactured using the BiCMOS process, which allows an operating current of 4mA. SG6742 integrates a frequency a hopping function that helps reduce EMI emission of a power supply with minimum line filters. Also, its built-in synchronized slope compensation achieves stable peak-current-mode control. The proprietary internal line compensation ensures constant output power limit over a wide AC input voltages, from 90VAC to 264VAC. SG6742 provides many protection functions. In addition to cycle-by-cycle current limiting, the internal open-loop protection circuit ensures safety should an open-loop or output short-circuit failure occur. PWM output is disabled until VDD drops below the UVLO lower limit when the controller starts up again. As long as VDD exceeds about 26V, the internal OVP circuit is triggered. SG6742 is available in an 8-pin DIP or SOP package. The highly integrated SG6742 series of PWM controllers provides several features to enhance the performance of flyback converters. TYPICAL APPLICATION © System General Corp. Version 1.0.1 (IAO33.0083.B0) -1- www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller MARKING INFORMATION SG6742TP XXXXXXXXYWWV PIN CONFIGURATION T: D = DIP, S = SOP P: Z =Lead Free Null=regular package XXXXXXXX: Wafer Lot Y: Year; WW: Week V: Assembly Location GND GATE FB VDD NC SENSE HV RT ORDERING INFORMATION Part Number PWM Frequency Pb-Free Package SG6742SZ 65KHz SOP-8 SG6742DZ (Preliminary) 65KHz DIP-8 PIN DESCRIPTIONS Pin No. Symbol Function Description 1 GND Ground Ground. 2 FB Feedback The signal from the external compensation circuit is fed into this pin. The PWM duty cycle is determined in response to the signal on this pin and the current-sense signal on SENSE pin. 3 NC NA NC pin. 4 HV Start-up Input For start-up, this pin is pulled high to the line input or bulk capacitor via resistors. 5 RT Temperature Detection For over-temperature protection, an external NTC thermistor is connected from this pin to GND pin. The impedance of the NTC decreases at high temperatures. Once the voltage of the RT pin drops below a fixed limit, PWM output is disabled. 6 SENSE Current Sense Current sense. The sensed voltage is used for peak-current-mode control and cycle-by-cycle current limiting. 7 VDD Power Supply Power supply. The internal protection circuit disables PWM output as long as VDD exceeds the OVP trigger point. 8 GATE Driver Output The totem-pole output driver. Soft driving waveform is implemented for improved EMI. © System General Corp. Version 1.0.1 (IAO33.0083.B0) -2- www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller BLOCK DIAGRAM © System General Corp. Version 1.0.1 (IAO33.0083.B0) -3- www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VDD Supply Voltage 30 V VHV Input Voltage to HV Pin 500 V VL Input Voltage to FB, SENSE, CS Pin -0.3 to 7.0 PD Power Dissipation TA < 50°C RΘ JA Thermal Resistance (Junction-to-Air） V DIP 800 SOP 400 DIP 82.5 SOP 141.0 mW °C/W TJ Operating Junction Temperature -40 to +125 TSTG Storage Temperature Range -55 to +150 °C TL Lead Temperature (Wave Soldering or Infrared, 10 Seconds) 260 °C ESD °C Electrostatic Discharge Capability, Human Body Model All pins except HV pin 4 KV Electrostatic Discharge Capability, Machine Model 400 V All pins except HV pin * All voltage values, except differential voltages, are given with respect to the GND pin. * Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. ELECTRICAL CHARACTERISTICS VDD ＝ 15V; TA ＝ 25°C, unless otherwise noted. VDD Section Symbol Parameter VDD-OP Continuously Operating Voltage Test Condition Min. Typ. Max. Unit 22 V VDD-ON Start Threshold Voltage 15.5 16.5 17.5 V VDD-OFF Minimum Operating Voltage 9.5 10.5 11.5 V IDD-ST Start-up Current VDD-ON – 0.16V 30 µA IDD-OP Operating Supply Current VDD = 15V, GATE open 4 5 mA IDD-OLP Internal Sink Current VTH-OLP+0.1V 50 70 90 µA VTH-OLP IDD-OLP Off Voltage 6.5 7.5 8.0 V VDD-OVP VDD Over-Voltage Protection 25 26 27 V tD-VDDOVP VDD Over-Voltage Protection Debounce Time 75 125 200 µs Min. Typ. Max. Unit HV Section Symbol Parameter Test Condition IHV Supply Current Drawn from HV Pin VAC=90V (VDC=120V)； VDD=10µF 1.2 IHV-LC Leakage Current After Start-up HV = 500V, VDD = VDD-OFF+1V 1 © System General Corp. Version 1.0.1 (IAO33.0083.B0) -4- mA 20 µA www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller Oscillator Section Symbol FOSC Parameter Frequency in Nominal Mode tHOP Hopping Period FOSC-G Green-Mode Frequency FDV Frequency Variation vs. VDD Deviation FDT Frequency Variation vs. Temp. Deviation Test Condition Min. Typ. Max. Center Frequency 62 65 68 Hopping Range ±3.7 ±4.2 ±4.7 4.4 18 22 Unit KHz ms 25 KHz VDD=11V to 22V 5 % TA=-20 to 85°C 5 % * Hopping off at green-mode. Feedback Input Section Symbol Parameter Min. Typ. Max. Unit AV Input Voltage to Current-Sense Attenuation Test Condition 1/4.5 1/4.0 1/3.5 V/V ZFB Input Impedance 4 VFB-OPEN Output High Voltage FB pin open 7 5.5 kΩ V VFB-OLP FB Open-Loop Trigger Level 5.0 5.2 5.4 V tD-OLP Delay Time of FB Pin Open Loop Protection 53 56 59 ms VFB-N Green-Mode Entry FB Voltage 1.9 2.1 2.3 V VFB-G Green-Mode Ending FB Voltage VFB-N-0.5 V PWM Frequency FOSC FOSC-G VFB-G © System General Corp. Version 1.0.1 (IAO33.0083.B0) VFB-N -5- VFB www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller Current-Sense Section Symbol Parameter ZSENSE Input Impedance VSTHFL Current Limit Flatten Threshold Voltage VSTHVA Current Limit Valley Threshold Voltage Test Condition Min. Typ. Max. Unit 12 VSTHFL–VSTHVA KΩ 0.87 0.90 0.93 V 0.18 0.22 0.26 V tPD Delay to Output 100 200 ns tLEB Leading-Edge Blanking Time 275 350 425 ns VS-SCP Threshold Voltage for SENSE Short-circuit Protection 0.10 0.15 0.20 V tD-SSCP Delay Time for SENSE Short-circuit Protection VSENSE < 0.15V 100 150 200 µs Test Condition Min. Typ. Max. Unit 60 65 70 % GATE Section Symbol Parameter DCYMAX Maximum Duty Cycle VGATE-L Gate Low Voltage VDD=15V, IO=50mA VGATE-H Gate High Voltage VDD=12V, IO=50mA 8 1.5 V tr Gate Rising Time VDD=15V, CL=1nF 150 250 350 ns tf Gate Falling Time VDD=15V, CL=1nF 30 50 90 ns IGATE-SOURCE Gate Source Current VDD=15V, GATE=6V 250 VGATE-CLAMP Gate Output Clamping Voltage VDD=22V 18 V V mA RT Section Symbol Parameter IRT Output Current from the RT Pin VRTTH1 Over-Temperature Protection Threshold Voltage VRTTH2 Test Condition Min. Typ. Max. Unit 92 100 108 µA 0.7V ＜ VRT ＜ 1.05V, after 1.015 12ms latch off 1.050 1.085 V Over-Temperature Protection Threshold Voltage VRT ＜ 0.7V, after 100µs latch off 0.70 0.75 V tD-OTP1 Over-Temperature Latch-off Debounce VRTTH2 ＜ VRT ＜ VRTTH1 8 12 16 ms tD-OTP2 Over-Temperature Latch-off Debounce VRT < VRTTH2 60 100 140 µs Test Condition Min. Typ. Max. Unit 0.65 Over Temperature Protection (OTP) Symbol Parameter TOTP Protection Junction Temperature* 135 °C TRestart Restart Junction Temperature** TOTP -25 °C * When activated, the output is disabled and the latch is turned off. ** This is the threshold temperature for enabling the output again and resetting the latch after over-temperature protection has been activated. © System General Corp. Version 1.0.1 (IAO33.0083.B0) -6- www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller TYPICAL CHARACTERISTICS Operating Supply Current (IDD-OP) vs Temperature 25 5 20 4 IDD-OP (mA) IDD_ST (uA) Start-up Current (IDD-ST) vs Temperature 15 10 5 0 -40 3 2 1 -30 -15 0 25 50 75 85 100 0 -40 125 -30 -15 0 Temperature (℃) 20 13 19 12 18 17 16 85 100 125 100 125 10 9 -30 -15 0 25 50 75 85 100 8 -40 125 -30 -15 0 25 50 75 85 Temperature (℃) Supply current drawn from pin HV (IHV) vs Temperature HV pin Leakage Current after Start-up (IHV-LC) vs Temperature 5 10 4 8 IHV-LC (uA) IHV (mA) 75 11 Temperature (℃) 3 2 1 0 -40 50 Minimum Operating Voltage (V DD-OFF) vs Temperature VDD-OFF (V) VDD-ON (V) Start Threshold Voltage (VDD-ON) vs Temperature) 15 -40 25 Temperature (℃) 6 4 2 -30 -15 0 25 50 75 85 100 0 -40 125 Temperature (℃) © System General Corp. Version 1.0.1 (IAO33.0083.B0) -30 -15 0 25 50 75 85 100 125 Temperature (℃) -7- www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller Maximum Duty Cycle (DCYMAX) vs Temperature 70 70 68 68 DCYMAX (%) FOSC (kHz) Frequency in nominal mode (FOSC) vs Temperature 66 64 62 60 -40 66 64 62 -30 -15 0 25 50 75 85 100 60 -40 125 Temperature (℃) -30 -15 0 25 50 75 85 100 125 Temperature (℃) Output Current from the RT pin (IRT) vs Temperature 104 IRT (uA) 102 100 98 96 94 -40 -30 -15 0 25 50 75 85 100 125 Temperature (℃) © System General Corp. Version 1.0.1 (IAO33.0083.B0) -8- www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller OPERATION DESCRIPTION Start-up Current Under-Voltage Lockout (UVLO) For start-up, the HV pin is connected to the line input or bulk capacitor through an external diode and resistor RHV, which are recommended as 1N4007 and 100KΩ. Typical start-up current drawn from the HV pin is 1.2mA and it charges the hold-up capacitor through the diode and resistor. When the VDD capacitor level reaches VDD-ON, the start-up current switches off. At this moment, the VDD capacitor only supplies the SG6742 to keep the VDD before the auxiliary winding of the main transformer to carry on provide the operating current. The turn-on and turn-off threshold are fixed internally at 16.5V/10.5V. During start-up, the hold-up capacitor must be charged to 16.5V through the start-up resistor so that IC is enabled. The hold-up capacitor continues to supply VDD before the energy can be delivered from auxiliary winding of the main transformer. VDD must not drop below 10.5V during this start-up process. This UVLO hysteresis window ensures that hold-up capacitor is adequate to supply VDD during start-up. Operating Current Operating current is around 4mA. The low operating current enables better efficiency and reduces the requirement of VDD hold-up capacitance. Green-Mode Operation The patented green-mode function provides an off-time modulation to reduce the switching frequency in light-load and no-load conditions. The on-time is limited for better abnormal or brownout protection. VFB, which is derived from the voltage feedback loop, is taken as the reference. Once VFB is lower than the threshold voltage, switching frequency is continuously decreased to the minimum green mode frequency, around 22KHz. Current Sensing / PWM Current Limiting Peak-current-mode control is utilized to regulate output voltage and provide pulse-by-pulse current limiting. The switch current is detected by a sense resistor into the SENSE pin. The PWM duty cycle is determined by this current sense signal and VFB, the feedback voltage. When the voltage on the SENSE pin reaches around VCOMP = (VFB–1.2)/4, a switch cycle is terminated immediately. VCOMP is internally clamped to a variable voltage around 0.85V for output power limit. Leading-Edge Blanking Each time the power MOSFET is switched on, a turn-on spike occurs on the sense-resistor. To avoid premature termination of the switching pulse, a leading-edge blanking time is built in. During this blanking period, the current-limit comparator is disabled and it cannot switch off the gate driver. © System General Corp. Version 1.0.1 (IAO33.0083.B0) Gate Output / Soft Driving The SG6742 BiCMOS output stage is a fast totem pole gate driver. Cross conduction is avoided to minimize heat dissipation, increases efficiency, and enhances reliability. The output driver is clamped by an internal 18V Zener diode to protect power MOSFET transistors against undesirable gate over voltage. A soft driving waveform is implemented to minimize EMI. Built-in Slope Compensation The sensed voltage across the current-sense resistor is used for peak-current-mode control and pulse-by-pulse current limiting. Built-in slope compensation improves stability or prevents sub-harmonic oscillation. SG6742 inserts a synchronized positive-going ramp at every switching cycle. Constant Output Power Limit When the SENSE voltage, across the sense resistor Rs, reaches the threshold voltage, around 0.9V, the output GATE drive is turned off after a small delay, tPD. This delay introduces additional current, proportional to tPD•VIN / LP. Since the delay is nearly constant, regardless of the input voltage VIN, higher input voltage results in a larger additional current and the output power limit is higher than under low input line voltage. To compensate this variation for wide AC input range, a sawtooth power-limiter is designed to solve the unequal power-limit problem. The power limiter is designed as a positive ramp signal and is fed to the inverting input of the OCP comparator. This results in a lower current limit at high-line inputs than at low-line inputs. -9- www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller VDD Over-Voltage Protection VDD over-voltage protection has been built in to prevent damage due to abnormal conditions. Once the VDD voltage is over the over-voltage protection voltage (VDD-OVP) and lasts for tD-VDDOVP, the PWM pulses are be disabled until the VDD voltage drops below the UVLO, then start-up again. Over-voltage conditions are usually caused by open feedback loops. Thermal Protection An NTC thermistor RNTC in series with a resistor RA can be connected from pin RT to ground. A constant current IRT is output from pin RT. The voltage on RT pin can be expressed as VRT = IRT × (RNTC + Ra), in which IRT = 2 x (1.3V / RI). At high ambient temperature, RNTC is smaller, such that VRT decreases. When VRT is less than 1.05V (VRTTH1), the PWM is turned off after 12ms (tD-OTP1). If VRT is less than 0.7V (VRTTH2), PWM should be turned off immediately after 100µs (tD-OTP2). When VDD goes below the turn-off threshold (eg, 10.5V) the controller is totally shut down. VDD is charged up to the turn-on threshold voltage of 16V through the start-up resistor until PWM output is restarted. This protection feature is activated as long as the over-loading condition persists. This prevents the power supply from overheating due to over loading conditions. Noise Immunity Noise on the current sense or control signal may cause significant pulse width jitter, particularly in continuous-conduction mode. Slope compensation helps alleviate this problem. Good placement and layout practices should be followed. Avoiding long PCB traces and component leads, locating compensation and filter components near the SG6742, and increasing the power MOS gate resistance improves performance. Limited Power Control The FB voltage increases every time the output of the power supply is shorted or over-loaded. If the FB voltage remains higher than a built-in threshold for longer than tD-OLP, PWM output is turned off. As PWM output is turned off, the supply voltage VDD begins decreasing. © System General Corp. Version 1.0.1 (IAO33.0083.B0) - 10 - www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller 2 REFERENCE CIRCUIT (12V/5A) F1 T1 4 2 4 L1 1 2 3 C6 1 VZ1 C1 4 C2 1 4 T2 8 2 5 R1 C5 1 VO+ VO+ 2 + L3 4 2 6 2 1 + C7 D1 C8 1 2 3 1 7 1 3 D2 1 1 D4 L2 1 C4 2 C3 Q1 2 3 + 2 3 1 3 2 3 1 CN1 R2 BD1 2 CN1 2 VO- 2 R3 R4 Q2 3 1 D3 2 2 1 2 C12 3 4 GND GATE FB VDD NC SENSE HV RT C9 8 1 U1 1 + SG6742 7 R5 6 5 R6 C10 R7 U2 R8 1 4 THER1 K 2 3 R9 VO+ R10 C11 R U3 A R11 BOM Reference Component Reference BD1 BD 4A/600V Q1 Component STP20-100CT C1 XC 0.68µF/300V Q2 MOS 7A/600V C2 XC 0.1µF/300V R1 R 100Kohm 1/2W C3 YC 222pF/Y1 R2 R 47ohm 1/4W C4 EC 120µF/400V R3 R 100Kohm 1/2W C5 CC 0.01µF/500V R4 R 20ohm 1/8W C6 CC 102pF/100V R5 R 100ohm 1/8W C7 EC 1000µF/25V R6 R 4.7Kohm 1/8W C8 EC 470µF/25V R7 R 0.3ohm 2W C9 EC 22µF/50V R8 R 680ohm 1/8W C10 CC 470pF/50V R9 R 4.7Kohm 1/8W C11 CC 222pF/50V R10 R 150Kohm 1/8W C12 CC 103pF/50V R11 R 39Kohm 1/8W D1 Zener Diode 15V 1/2W (option) THER1 Thermistor TTC104 D2 BYV95C T1 10mH D3 FR103 T2 600µH(PQ2620) D4 1N4007 U1 IC SG6742 F1 FUSE 4A/250V U2 IC PC817 L1 Inductor (900µH) U3 IC TL431 L2 Inductor (2µH) VZ1 VZ 9G L3 Inductor (900µH) © System General Corp. Version 1.0.1 (IAO33.0083.B0) - 11 - www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller PACKAGE INFORMATION 8PINS-DIP(D) D Θ¢X 5 E1 8 e B E A A1 A2 4 1 L b1 b e Dimensions Symbol Millimeters Min. Typ. A Max. Inches Min. Typ. 5.334 A1 0.381 A2 3.175 0.210 0.015 3.302 3.429 0.125 0.130 b 1.524 0.060 b1 0.457 0.018 D 9.017 9.271 6.223 6.350 E E1 10.160 0.355 0.365 6.477 0.245 0.250 7.620 e Max. 0.135 0.400 0.300 2.540 0.255 0.100 L 2.921 3.302 3.810 0.115 0.130 0.150 eB 8.509 9.017 9.525 0.335 0.355 0.375 θ˚ 0˚ 7˚ 15˚ 0˚ 7˚ 15˚ © System General Corp. Version 1.0.1 (IAO33.0083.B0) - 12 - www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller 8PINS-SOP(S) 8 C 5 H E F 1 4 b e D Θ A1 L A Dimensions Symbol Millimeter Min. Typ. Max. Inch Min. A A1 b c D E e F H L θ˚ 1.346 0.101 1.752 0.254 0.053 0.004 0.406 0.203 4.648 3.810 1.016 5.791 0.406 0° © System General Corp. Version 1.0.1 (IAO33.0083.B0) 1.270 0.381X45° Typ. Max. 0.069 0.010 0.016 0.008 4.978 3.987 1.524 0.183 0.150 0.040 6.197 1.270 8° 0.228 0.016 0° - 13 - 0.050 0.015X45° 0.196 0.157 0.060 0.244 0.050 8° www.sg.com.tw • www.fairchildsemi.com September 24, 2007 Product Specification SG6742 Highly Integrated Green-Mode PWM Controller © System General Corp. Version 1.0.1 (IAO33.0083.B0) - 14 - www.sg.com.tw • www.fairchildsemi.com September 24, 2007