Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller the switching frequency under light-load conditions. Under zero-load conditions, the power supply enters burst-mode. This completely shuts off PWM output. The output restarts just before the supply voltage drops below the UVLO lower limit. This green-mode function enables power supplies to easily meet international power conservation requirements. FEATURES Two-level OCP with 96mS delay time Peak-current-mode operation with cycle-by-cycle current limiting PWM frequency continuously decreasing w/ burst mode at light loads Low start-up current (8uA) Low operating current (3.7mA) VDD over-voltage protection (OVP) AC input brownout protection with hysteresis Programmable over-temperature protection (OTP) Constant power limit over universal AC input range Internal latch circuit for OTP, OVP, OCP Very few external components APPLICATIONS General-purpose switch mode power supplies and flyback power converters, including: Power adapters Open-frame SMPS Specifically fit for SMPS with surge-current output, such as for printers, scanners, motor drivers, etc. DESCRIPTION The highly integrated SG6846 series of PWM controllers provides several features to enhance the performance of flyback converters. To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to continuously decrease The SG6846 is especially designed for SMPS with surge-current output. It is incorporated with a two-level OCP function. Besides the cycle-by-cycle current limiting, if the switching current is higher than 2/3 of the peak-current threshold for a delay time, over-current protection will be activated such that the SG6846 will be totally shutdown. Other protection functions include: AC input brownout protection with hysteresis, and VDD over-voltage protection. For over-temperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When OCP, VDD OVP, or OTP are activated, an internal latch circuit is used to latch-off the controller. The latch will reset when the VDD supply is removed. Other features of this controller include: Built-in synchronized slope compensation, proprietary internal compensation for constant output power limit over universal AC input range. Also, the gate output is clamped at 18V to protect the external MOSFET from over-voltage damage. The SG6846 series controllers are available in both 8-pin DIP and SO packages. TYPICAL APPLICATION (c) System General Corp. Version 1.0(IAO33.0008.B0) -1- www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller MARKING DIAGRAMS PIN CONFIGURATION F: L = OTP Latch C = Hysteresis OTP 8 T: D = DIP, S = SOP SG6846FTP MXXXXXXYYWWV 1 GND 1 8 GATE FB 2 7 VDD M: Mask version VIN 3 6 SENSE XXXXXX: Wafer Lot RI 4 5 RT P: Null = regular Z = Lead free YY: Year; WW: Week V: Assembly Location ORDERING INFORMATION Part Number Package OTP Mode SG6846LS 8-Pin SOP Latch off SG6846LD 8-Pin DIP Latch off SG6846CS 8-Pin SOP Hysteresis SG6846CD 8-Pin DIP Hysteresis SG6846LSZ 8-Pin SOP (Lead Free) Latch off SG6846LDZ 8-Pin DIP (Lead Free) Latch off SG6846CSZ 8-Pin SOP (Lead Free) Hysteresis SG6846CDZ 8-Pin DIP (Lead Free) Hysteresis (c) System General Corp. Version 1.0(IAO33.0008.B0) -2- www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller PIN DESCRIPTIONS Pin No. Symbol Function Description Ground. 1 GND Ground 2 FB Feedback 3 VIN 4 5 RI RT Line-voltage Detection Reference Setting Temperature Detection The signal from the external compensation circuit is fed into this pin. This FB pin and the current-sense signal from Pin 6 determine the PWM duty cycle. Line-voltage detection. The line-voltage detection is used for brownout protection with hysteresis. Constant output power limit over universal AC input range is also achieved using this VIN signal. It is suggested to add low pass filter to filter out line ripple on bulk capacitor. A resistor from the RI pin to ground will generate a reference current source inside SG6846. This determines the switching frequency. Increasing the resistance will reduce the switching frequency. Using a 26k resistor Ri results in a 65kHz switching frequency. For over-temperature protection. An external NTC thermistor is connected from this pin to GND pin. The impedance of the NTC will decrease at high temperatures. Once the voltage of the RT pin drops below a threshold, PWM output will be disabled. Current sense. The sensed voltage is used for peak-current-mode control and 6 SENSE Current Sense cycle-by-cycle current limiting. If the switching current is higher than 2/3 of the peak-current threshold for longer than 96ms, over-current protection will be activated. This two-level OCP feature is especially suitable for SMPS with surge current output. 7 VDD Power Supply 8 GATE Driver Output Power Supply. The internal protection circuit will disable PWM output when VDD over voltage. The totem-pole output driver for the power MOSFET. A soft driving waveform is implemented for improved EMI. BLOCK DIAGRAM (OTP LATCH VERSION) (c) System General Corp. Version 1.0(IAO33.0008.B0) -3- www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller ABSOLUTE MAXIMUM RATINGS Symbol Parameter VDD Supply Voltage 25 V VL Input Voltage to VIN, FB, SENSE, RT, RI Pin -0.3 to 7V V PD Power Dissipation R J-C Thermal Resistance TJ Operating Ambient Temperature TSTG Storage Temperature Range TL Lead Temperature (Soldering) Test Condition at T A < 50C Value DIP 800 SOP 400 DIP 67.1 SOP 41.2 Junction-Case Unit mW C/W -40 to 125 C -65 to +150 C 10 sec DIP 260 10 sec SOP 230 C *All voltage values, except differential voltages, are given with respect to GND pin. *Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. RECOMMENDED OPERATING JUNCTION TEMPERATURE: -30C ~ 85C* *For proper operation ELECTRICAL CHARACTERISTICS (VDD = 15V, T A = 27C, unless noted) VDD Section Symbol Parameter VOP Continuously Operating Voltage VTH-ON On Threshold Voltage VTH-OFF Off Threshold Voltage IDD-ST Start-Up Current VDD = 15V IDD-OP Operating Supply Current GATE Open VDD-OVP VDD Over Voltage Protection (Latch off) TVDD-OVP VDD OVP Debounce Time IDD-OVP VDD-TH-G VDD OVP Latch-up Holding Current Test Condition Min. Typ. 15.5 16.5 9.5 22.6 RI = 26K o VDD = 5V, TA = 27 C Max. Unit 20 V 17.5 V 10.5 11.5 V 8 30 uA 3.7 5 mA 23.6 24.6 V 100 usec 45 uA VDD Low-threshold Voltage to Exit Green-OFF VTH(OFF) + Mode 1.25 V VIN Section Symbol Parameter VIN-OFF PWM Turn-off Threshold Voltage VIN-ON PWM Turn-on Threshold Voltage Test Condition Min. Typ. Max. Unit 0.67 0.72 0.77 V VIN-OFF + V 0.2 Feedback Input Section Symbol Parameter AV Input-Voltage to Current-Sense Attenuation ZFB Input Impedance VFB0 FB Pin open voltage (c) System General Corp. Version 1.0(IAO33.0008.B0) Test Condition Min. Typ. Max. 1/4.2 4 5.5 6.2 -4- Unit V/V 7 K V www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller Current Sense Section Symbol Parameter ZCS Input Impedance Test Condition Min. Typ. 12 Max. Unit TPD Delay to Output 100 BNK Leading Edge Blanking Time 360 nsec VTH-P @VIN=1V Threshold Voltage for Current Limit VIN = 1V, RI = 26k 0.83 V VTH-P @VIN=3V Threshold Voltage for Current Limit VIN =3V, RI = 26k 0.70 V VTH-O @VIN=1V 2/3 Threshold Voltage for Current Limit VIN = 1V, RI = 26k 0.61 V VTH-O @VIN=3V 2/3 Threshold Voltage for Current Limit VIN =3V, RI = 26k 0.51 V TDELAY-OCP The Delay Time for Over-current Protection RI = 26K 96 msec k 200 nsec Oscillator Section Symbol Parameter Test Condition Min. Typ. Max. Unit FOSC PWM Frequency RI = 26k 60 65 70 KHz Green-mode Frequency RI = 26k 20 22.5 25 KHz FOSC-GREEN VN FB Pin Threshold for the Beginning of Green 2.1 Mode VG Green-OFF Mode Voltage at FB pin SG Slope for Green-Mode Modulation RI = 26k FDV Frequency Variation Versus VDD Deviation VDD = 11.5V to 20V FDT Frequency Variation Versus Temp. Deviation TA = -30 to 85 V 1.6 V 85 Hz/mV 1.5 5 % 5 % Frequenc y PWM Frequency FOSC: 65kHz SG: 85Hz/mV FOSC-GREEN: 22.5kHz FOSC-GOFF: 0kHz VF VG: 1.6V VN: 2.1V B (c) System General Corp. Version 1.0(IAO33.0008.B0) -5- www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller PWM Section Symbol Parameter DMAX Maximum Duty Cycle Test Condition Min. Typ. Max. Unit 80 85 90 % VOL Output Voltage Low VDD = 15V, Io = 50mA VOH Output Voltage High VDD = 12V, Io = 50mA 1.5 V TR Rising Time VDD = 15V, CL=1nF 350 nsec TF Falling Time VDD = 15V, CL=1nF 50 nsec VCLAMP Gate Output Clamping Voltage VDD = 20V 18 V 8V V Over Temperature Protection Section Symbol Parameter Test Condition Min. Typ. Max. Unit IRT Output Current of RT Pin RI = 26k 64 70 76 uA 1.015 1.065 1.115 V VOTP-LATCH-OFF Threshold Voltage for Over-Temperature Protection. TDOTP-LATCH Over-Temperature Latch-Off Debounce. VOTP-RESET OTP Release Voltage (for non-latch-off version) RI = 26k 100 usec VOTP-LATCH- V OFF + 0.1 RI Section Symbol Parameter Test Condition Min. Typ. Unit 36 k RINOR RI Operating Range RIMAX Max. RI value for Protection 216 k RIMIN Min. RI value for Protection 6 k (c) System General Corp. Version 1.0(IAO33.0008.B0) 15.5 Max. -6- www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller TYPICAL CHARACTERISTICS Min. Opperating Voltage vs Temperature Start-up Threshold Voltage vs Temperature 17.5 11.5 11.3 11.1 VTH-OFF (V) VTH-ON (V) 17.0 16.5 16.0 10.9 10.7 10.5 10.3 10.1 9.9 9.7 9.5 15.5 -40 -25 -10 5 20 35 50 65 80 95 110 -40 125 -25 -10 5 50 65 80 95 110 125 Start-up Current vs VDD Voltage Start-up Current vs Temperature 20 16.000 16 IDD-ST (uA) 15.500 15.000 14.500 12 8 4 14.000 0 13.500 -40 -25 -10 5 20 35 50 65 80 95 110 125 5 10 15 Temperature () 20 VDD (V) PWM Turn-on Threshold Voltage vs Temperature PWM Turn-off Threshold Voltage vs Temperature 1.000 1.000 0.900 0.900 0.800 0.800 VIN-ON (V) V IN-OFF (V) 35 Temperature ( ) Temperature () IDD-ST (uA) 20 0.700 0.600 0.700 0.600 0.500 0.500 0.400 0.400 -40 -25 -10 5 20 35 50 65 80 95 110 -40 125 (c) System General Corp. Version 1.0(IAO33.0008.B0) -25 -10 5 20 35 50 65 80 95 110 125 Temperature ( ) Temperature ( ) -7- www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller PWM Frequency vs FB Voltage (RI = 26K) PWM Frequency vs Temperature PWM Frequency (Khz) 65.300 FOSC (Khz) 65.200 65.100 65.000 64.900 64.800 64.700 60 40 20 0 64.600 -40 -25 -10 5 20 35 50 65 80 95 110 125 1.5 1.6 1.7 1.8 Temperature () Current-limit Threshold vs VIN Voltage 2 2.1 2.2 2.3 2/3 Current-limit Threshold vs VIN Voltage 1 1 0.8 0.8 VTH-O (V) VTH-P (V) 1.9 VFB (V) 0.6 0.4 0.6 0.4 0.2 0.2 0 0 1 1.5 2 2.5 1 3 1.5 2 2.5 3 VIN (V) VIN (V) OTP Threshold Voltage vs Temperature Output Current of pin RT vs Temperature 1.115 78.000 77.000 1.095 VOTP-OFF (V) IRT (uA) 76.000 75.000 74.000 73.000 72.000 1.075 1.055 1.035 71.000 1.015 70.000 -40 -25 -10 5 20 35 50 65 80 95 110 -40 125 -10 5 20 35 50 65 80 95 110 125 Temperature ( ) Temperature ( ) (c) System General Corp. Version 1.0(IAO33.0008.B0) -25 -8- www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller OPERATION DESCRIPTION Start-up Operation The turn-on/turn-off thresholds are fixed internally at 16.5V/10.5V. To enable the SG6846 during start-up, the hold-up capacitor must first be charged to 16.5V through the start-up resistor. The hold-up capacitor will continue to supply VDD before energy can be delivered from the auxiliary winding of the main transformer. The VDD must not drop below 10.5V during this start-up process. This UVLO hysteresis window ensures that the hold-up capacitor can adequately supply VDD during start-up. The typical start-up current is only 8uA. This allows a high resistance, low-wattage start-up resistor to be used, to minimize power loss. A 1.5 M/0.25W, start-up resistor and a 10uF/25V VDD hold-up capacitor would be sufficient for a universal input range. The required operating current has been reduced to 3.7mA. This enables higher efficiency and reduces the VDD hold-up capacitance requirement. Green-Mode Operation The proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Maximum on time is limited to provide protection against abnormal conditions. To further reduce power consumption under zero-load condition, the PWM oscillator will be completely turned off, and the power supply will enter burst-mode. After the PWM oscillator is turned off, the IC's supply voltage VDD will drop gradually. Before the VDD voltage drops below the UVLO threshold, the PWM oscillator will be turned on again. This green-mode function dramatically reduces power consumption under light-load and zero-load conditions. Power supplies using the SG6846 can easily meet even the most restrictive international regulations regarding standby power consumption. This current is used to determine the PWM frequency. Increasing the resistance will decrease the amplitude of the current source and reduce the PWM frequency. Using a 26k resistor Ri results in a corresponding 65kHz switching frequency. The relationship between RI and the switching frequency is: fPWM (kHz) = 1690 Ri (k ) ---------------------------- (1) If an open circuit or short circuit to ground occurs at the RI pin, the internal protection circuit will immediately shut down the controller. Two-level Over-current Protection The cycle-by-cycle current limiting will shut down the PWM immediately when the switching current is over the peak-current threshold. Additionally, when the switching current is higher than 2/3 of the peak-current threshold, the internal counter starts counting up. When the switching current is lower than 2/3 of the peak current threshold, the internal counter will count down. When the total accumulated counting time is more than about 96ms (Ri = 26kohm), the controller will be latched off. This two-level OCP protection and up/down counter are especially designed for SMPS with surge current output such as those for printers, scanners, motor drivers, etc. Constant Output Power Limit For constant output power limit over universal input-voltage range, the peak-current threshold is adjusted by the voltage of the VIN pin. Since the VIN pin is connected to the rectified AC input line voltage through the resistive divider, a higher line voltage will generate a higher VIN voltage. The threshold voltage decreases as the VIN voltage increases, making the max. output power at high line input voltage equal to that at low line input. Brownout Protection Since the VIN pin is connected through a resistive divider to the rectified AC input line voltage, it can also be used for brownout protection. If the VIN voltage is less A resistor connected from the RI pin to GND than 0.72V, the PWM output will be shut off. As the VIN generates a reference current source inside the SG6846. (c) System General Corp. -9www.sg.com.tw Version 1.0(IAO33.0008.B0) Sep. 30, 2004 Oscillator Operation Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller voltage over 0.92V, the PWM output will be turned on again. The hysteresis window for ON/OFF is around 0.2V. RT pin drops below 1.065V, the SG6846 will be turned off. There are two options for the protection modes, please see ORDER INFORMATION. Noise immunity VDD Over-voltage Protection VDD over-voltage protection is built in to prevent the controller from over-voltage destruction. When VDD voltage is over 23.6V, the SG6846 is latched off. Over-temperature Protection An external NTC thermistor can be connected from the RT pin to GND. The impedance of the NTC will decrease at high temperatures. When the voltage of the (c) System General Corp. Version 1.0(IAO33.0008.B0) - 10 - Noise from the current sense or the 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. The designer should avoiding long PCB traces and component leads. Compensation and filter components should be located near the SG6846. www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller REFERENCE CIRCUIT Application circuit for 32V/16V output R16 D4 1 R3 D1 L4 12 2 D3 7 1 9 3 11 2 C11 2 R17 P16V P16V L2 1 C5 R11 + 2 C17+ 3 1 C3 1 + 32V 10 D2 2 21 2 1 R4 32V C13 + 1 C2 R9 C12 + C14 2 R2 C16+ 3 6 2 P7 R12 C4 1 3 + P32V P32V L1 2 1 R8 R1 13 2 5 2 1 2 4 4 1 1 CX2 CY2 3 1 P2 TX1 2 2 VZ1 LF1 BD1 1 CX1LF2 3 4 CY1 2 RT1 2 F1 t P1 + 16V 16V C15 + 2 1 + R5 4 FB VDD VIN 1 Q1 R13 1 2 8 3 2 3 C1 GATE SENSE RI RT 7 5 L3 R6 6 R10 C6 1 FB GND 2 U1 1 1 1 D5 R14 NTC1 R7 P16V P16V P16V 1 FB 4 R15 FB C7 R18 K 2 3 U2 P32V P16V C9 R R20 R21 A U3 P32V R19 BOM PART NO. VALUE PART NO. VALUE PART NO. VALUE R1, R2, R3, R4 470K +/-5% C4 103 P 630V D3 FR103 1.0A 200V R8, R9 S1M +/-1% C10,C11 102 P 1KV BD1 DBL406G R5 16K2 +/-1% C6,C7 102 P 50V D4 BYT28-300 R15 1K5 +/-5% C9 222 P 50V D5 BYV32-150 R13 10 +/-5% C14,C17 470u 25V F1 250V4A QUICK R18 4K7 +/-5% C15 220u 25V L1,L2 1.8uH R21 15K +/-1% C13,C16 220u 50V L4 10uH R7 27K +/-5% C2 150u 400V U3 TL431 +/-1% R6 330 +/-1% C1 4u7 50V U1 SG 6846 R19 102K +/-1% C3 10u 50V U2 PC817 R14 022 +/-5% CX1 X1 0.47u 275V Q1 7NB60 R16, R17 1W 20 +/-5% C8 Y2 222P 250V TX1 EI-33 R11 20K +/-5% C5 100u 50V RT1 SCK053 R12 100K +/-5% CX2 X2 0.1uF 275V VZ1 14 470V R20 887K +/-1% D1 1N4148 R22 10K +/-1% D2 BYV95C (c) System General Corp. Version 1.0(IAO33.0008.B0) - 11 - www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller PACKAGE INFORMATION DIP-8 Outline Dimensions D 5 E1 8 B A A2 4 A1 1 e E L b1 e b Dimension Symbol A A1 A2 b b1 D E E1 e L eB Millimeter Min. 0.381 3.175 9.017 6.223 2.921 8.509 0 (c) System General Corp. Version 1.0(IAO33.0008.B0) Inch Min. Typ. Max. 5.334 3.302 1.524 0.457 9.271 7.620 6.350 2.540 3.302 9.017 7 3.429 0.015 0.125 10.160 0.355 6.477 0.245 3.810 9.525 15 0.115 0.335 0 - 12 - Typ. Max. 0.210 0.130 0.060 0.018 0.365 0.300 0.250 0.100 0.130 0.355 7 0.135 0.400 0.255 0.150 0.375 15 www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller SOP-8 Outline Dimensions C 5 E H 8 F 1 4 b e D A1 L A Dimension: Symbol A A1 b c D E e F H L Millimeter Min. 1.346 0.101 (c) System General Corp. Version 1.0(IAO33.0008.B0) Typ. Max. 1.752 0.254 Inch Min. 0.053 0.004 0.406 0.203 4.648 3.810 Max. 0.069 0.010 0.016 0.008 4.978 3.987 0.183 0.150 1.270 0.196 0.157 0.050 0.381X45 5.791 0.406 0 Typ. 0.015X45 6.197 1.270 8 - 13 - 0.228 0.016 0 0.244 0.050 8 www.sg.com.tw Sep. 30, 2004 Product Specification SG6846 Highly-Integrated Green-Mode PWM Controller DISCLAIMERS LIFE SUPPORT System General's products are not designed to be used as components in devices intended to support or sustain human life. Use of System General's products in components intended for surgical implant into the body, or other applications in which failure of System General's products could create a situation where personal death or injury may occur, is not authorized without the express written approval of System General's Chief Executive Officer. System General will not be held liable for any damages or claims resulting from the use of its products in medical applications. MILITARY System General's products are not designed for use in military applications. Use of System General's products in military applications is not authorized without the express written approval of System General's Chief Executive Officer. System General will not be held liable for any damages or claims resulting from the use of its products in military applications. RIGHT TO MAKE CHANGES System General reserves the right to change this document and/or this product without notice. Customers are advised to consult their System General sales representative before ordering. (c) System General Corp. Version 1.0(IAO33.0008.B0) - 14 - www.sg.com.tw Sep. 30, 2004