SG6846WA Highly Integrated Green-Mode PWM Controller Features Description Low Startup Current: 15µA PWM Frequency Continuously Decreasing with Burst Mode at Light Loads The SG6846WA is designed for SMPS with surgecurrent output, incorporated with a two-level OCP function. Besides the cycle-by-cycle current limiting, if the switching current is higher than two thirds the peakcurrent threshold for 1700ms, over-current protection is activated such that the SG6846WA is latched off. VDD Over-Voltage Protection (OVP) OCP Threshold is Half Peak Current Limit Built-in Soft-Start Low Operating Current: 3.7mA Peak-Current Mode of Operation with Cycle-by-Cycle Current Limiting AC Input Brownout Protection with Hysteresis Constant Output Power Limit (Full AC Input Range) Internal Latch Circuit for OVP, OTP, and OCP SG6846WA also integrates a frequency-hopping function that helps reduce EMI emission of a power supply with minimum line filters. The built-in synchronized slope compensation helps achieve stable peak-current control. To keep constant output power limit over universal AC input range, the current limit and OCP threshold voltage are adjusted according to the AC line voltage detected by the VIN pin. The gate output is clamped at 18V to protect the external MOSFET from over-voltage damage. Internal soft-start is built-in to reduce stress on the MOSFET and startup current during power-on period. Two-Level OCP Delay: 1700ms Output Short-Circuited Delay Time: 100ms Programmable PWM Frequency with Frequency Hopping Feedback Open-Loop Protection with a 1700ms Delay Other protection functions include AC input brownout protection with hysteresis, VDD over-voltage protection, and over-temperature protection. For over-temperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When OCP, VDD OVP, or OTP is activated; an internal latch circuit latches off the controller. The PWM pulses stay latched off until the power supply is disconnected from the mains outlet. Applications General-purpose switch-mode power supplies and flyback power converters, including: If the switching current is higher than two thirds of the peak-current threshold for 100ms and the voltage on the VDD is still higher than VDD-OFF + 1V; the PWM pulses are latched off immediately until the VDD voltage is lower than VDD-OFF + 1V. This is useful when an output short circuit occurs. Power Adapters Open-Frame SMPS SMPS with Surge-Current Output, such as for Printers, Scanners, Motor Drivers SG6846WA is available in 8-pin, SOP package. Ordering Information Part Number SG6846WALSY Operating Temperature Range OCP Latch -40 to +105°C Yes © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 Package 8-Pin, Small-Outline Package (SOP) Packing Method Tape & Reel www.fairchildsemi.com SG6846WA — Highly Integrated Green-Mode PWM Controller June 2012 Figure 1. Typical Application Block Diagram SG6846WA — Highly Integrated Green-Mode PWM Controller Typical Application Figure 2. Block Diagram © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 www.fairchildsemi.com 2 SG6846WA — Highly Integrated Green-Mode PWM Controller Marking Information : Z: X: Y: TT: F: T: P: M: Fairchild Logo Plant Code Year Code Week Code Die Run Code L = OCP Latch, C = OCP Auto-Recovery Package Type, S = SOP Y = Green Package Manufacturing Flow Code ※ Marking for SG6846WALSY (Green-Compound) Figure 3. Top Mark Figure 4. Pin Configuration (Top View) Pin Definitions Pin # Name Description 1 GND 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 from this pin and the current-sense signal from the SENSE pin (pin 6). 3 VIN Line-Voltage Detection. Line-voltage detection is used for brownout protection with hysteresis. Constant output power limit over universal AC input range is achieved using this pin. Add a low-pass filter to filter out line ripple on the bulk capacitor. 4 RI Reference Setting. A resistor from the RI pin to ground generates a reference current source that determines the switching frequency. Increasing the resistance reduces the switching frequency. A 26kΩ resistor results in a 65kHz switching frequency. 5 RT Temperature Detection. For over-temperature protection, an external NTC thermistor is connected from this pin to the GND pin. The impedance of the NTC decreases at high temperatures. Once the voltage on the RT pin drops below a threshold, PWM output is disabled. 6 7 8 Ground. Current Sense. The sensed voltage is used for peak-current-mode control and cycle-by-cycle current limiting. If the switching current is higher than OCP threshold and lasts for 1700ms, SENSE SG6846WA turns off immediately. This two-level OCP feature is especially suitable for SMPS with surge current output. VDD Supply Voltage. If an open-circuit failure occurs in the feedback loop, the internal protection circuit disables PWM output as long as VDD exceeds the threshold. GATE Driver Output. The totem-pole output driver for the power MOSFET; internally clamped below 18V. © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 www.fairchildsemi.com 3 Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. All voltage values, except differential voltages, are given with respect to GND pin. Symbol Parameter Min. Max. Unit 25 V -0.3 7.0 V 650 mW VDD Supply Voltage VL Input Voltage to FB, SENSE, VIN, RT, RI Pins PD Power Dissipation at TA=50°C ΘJA Thermal Resistance (Junction-to-Ambient) 150 °C/W TJ Operating Junction Temperature -40 +150 °C Storage Temperature Range -65 +150 °C +260 °C TSTG TL ESD Lead Temperature, Wave Soldering, 10 Seconds Electrostatic Discharge Capability Human Body Model, JESD22-A114 5500 Charge Device Model, JESD22-C101 2000 V Recommended Operating Conditions The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings. Symbol TA Parameter Operating Ambient Temperature © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 Min. Max. Unit -40 +105 °C SG6846WA — Highly Integrated Green-Mode PWM Controller Absolute Maximum Ratings www.fairchildsemi.com 4 VDD = 15V and TA = 25°C unless otherwise noted. Symbol Parameter Test Condition Min. Typ. Max. Unit 20 V VDD Section VDD-OP Continuously Operating Voltage VDD-ON Turn-On Threshold Voltage 15.5 16.5 17.5 V VDD-OFF Turn-Off Voltage 9.5 10.5 11.5 V VDD-SCP Threshold Voltage on VDD for Short-Circuit Protection VDD-LH Threshold Voltage for Latch-Off Release IDD-ST Startup Current VDD-ON – 0.16V 15 30 µA IDD-OP Operating Supply Current GATE Open 3.7 5.0 mA 22.8 24.0 25.2 V VDD-OFF +1.0V V 4 V VDD-OVP VDD Over-Voltage Protection (Latch-Off) tD-VDDOVP VDD OVP Debounce Time RI = 26kΩ 80 180 280 µs VDD OVP Latch-Off Holding Current VDD = 5V 30 50 70 µA 0.65 0.70 0.75 V IDD-OVP VIN Section VIN-OFF PWM Turn-Off Threshold Voltage VIN-ON PWM Turn-On Threshold Voltage VIN-OFF +0.20 V Feedback Input Section AV Input-Voltage to Current-Sense Attenuation ZFB VFBO VFB-OLP tD-OLP 1/3.5 1/4.0 1/4.5 V/V Input Impedance 4.0 5.5 7.0 kΩ FB Pin Open Voltage 5.6 6.0 6.4 V Threshold Voltage of Open-Loop Protection 4.1 4.6 5.1 V Open-Loop Protection Delay RI = 26kΩ 1700 ms 12 kΩ SG6846WA — Highly Integrated Green-Mode PWM Controller Electrical Characteristics Current Sense Section ZSENSE Input Impedance tPD Delay to Output 60 95 130 ns tLEB Leading-Edge Blanking Time 220 310 400 ns VSLOPE Slope Compensation Duty = DCYMAX VSTH1V Threshold Voltage for Current Limit VIN = 1V 0.80 0.83 0.86 V VSTH3V Threshold Voltage for Current Limit VIN = 3V 0.67 0.70 0.73 V VSTH1V-2/3 OCP Threshold Voltage for Current Limit VIN = 1V 0.53 0.58 0.63 V VSTH3V-2/3 OCP Threshold Voltage for Current Limit VIN = 3V 0.44 0.49 0.54 V tD-OCP Delay for Over-Current Protection RI = 26kΩ 1600 1700 1800 ms tD-SCP Delay for Output Short-Circuited Protection RI = 26kΩ; VDD<VDD-SCP tSS-65KHz tSS-130KHz Period During Startup Time 0.33 V 100 ms RI = 26kΩ 4.3 5.1 5.9 ms RI = 13kΩ 1.0 2.2 3.4 ms Continued on following page… © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 www.fairchildsemi.com 5 YES NO NO (2) IP > 2/3I PK or FB >VFB-OLP (5 ) Timing = 1700ms YES NO (6 ) VDD < = 12 V SCP OCP (3) Timing = 100 ms (7) Gate Off SCP Figure 5. OCP/SCP Logic Flow Diagram Electrical Characteristics (Continued) VDD = 15V and TA = 25°C unless otherwise noted. Symbol Parameter Test Condition Min. Typ. Max. 62 65 68 Unit Oscillator Section fOSC Normal PWM Frequency Center Frequency RI = 26kΩ, VFB>VN Hopping Range fOSC,MAX fOSC,MIN Maximum PWM Frequency Center Frequency 130 RI = 13kΩ, VFB>VN Hopping Range kHz ±8.4 Center Minimum PWM Frequency Frequency 47.00 RI = 36kΩ, VFB>VN Hopping Range thop kHz ±4.4 SG6846WA — Highly Integrated Green-Mode PWM Controller (4) VDD < 12 V (1) Normal Operation kHz ±2.90 Hopping Period RI = 26kΩ fOSC-G Green-Mode Minimum Frequency RI = 26kΩ VFB-N FB Pin Frequency Reduction Threshold VFB-G FB Voltage at fOSC-G FB Pin Voltage RI = 26kΩ, VFB = VN Hopping Range FB Pin Voltage RI = 26kΩ, VFB = VG Hopping Range SG Slope for Green-Mode Modulation RI = 26kΩ fDV Frequency Variation vs. VDD Deviation VDD = 11.5V to 20V fDT Frequency Variation vs. Temperature Deviation TA = -30 to 85°C ms 11.5 17.50 21.00 24.50 kHz 1.90 2.10 2.30 V KHz ±4.40 1.40 1.60 1.80 V ±1.45 KHz 85 Hz/mV 1.5 5 % 5.0 % Continued on following page… © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 www.fairchildsemi.com 6 Electrical Characteristics (Continued) VDD = 15V and TA = 25°C unless otherwise noted. Symbol Parameter Test Condition Min. Typ. Max. Unit 70 75 80 % 1.5 V PWM Output Section DCYMAX Maximum Duty Cycle VOL Output Voltage LOW VDD = 15V, IO = 50mA VOH Output Voltage HIGH VDD = 12V, IO = 50mA tR Rise Time GATE = 1nF 170 260 350 ns tF Fall Time GATE = 1nF 30 50 70 ns 18 V 76 µA VCLAMP Gate Output Clamping Voltage Over-Temperature Protection (OTP) Section IRT VRTTH tDOTP-LATCH RRT-OFF 8 SG6846WA — Highly Integrated Green-Mode PWM Controller Figure 6. PWM Frequency V VDD = 20V (1) Output Current of RT Pin RI = 26kΩ 64 Threshold Voltage for OTP 70 1.065 Over-Temperature Latch-Off Debounce RI = 26kΩ (1) Equivalent Impedance of RT for OTP 80 RI = 26kΩ 100 V 120 15 ms kΩ RI Section RINOR RI Operating Range 13 RIMAX Maximum RI Value for Protection 10 RIMIN Minimum RI Value for Protection 36 kΩ MΩ 6 kΩ Note: 1. The relationship between RRT-OFF and RI is: RRT-OFF = VOTP-LATCH-OFF / IRT = VRT / (70μA × 26 / RI (KΩ)) © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 (1) www.fairchildsemi.com 7 11.5 18 11.1 16 10.7 VDD-OFF (V) VDD-ON (V) 20 14 12 10 10.3 9.9 9.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 Temperature (℃ ) 35 50 65 80 95 110 125 Figure 8. Turn-off Threshold Voltage (VDD-OFF) vs. Temperature 30.0 10 26.8 8 23.6 6 IDD-ST (µA) IDD-ST (µA) 20 Temperature (℃) Figure 7. Turn-on Threshold Voltage (VDD-ON) vs. Temperature 20.4 17.2 14.0 -40 -25 -10 5 20 35 50 65 80 4 2 0 10 95 110 125 11 12 13 14 15 16 VDD (V) Temperature (℃) Figure 9. Startup Current (IDD-ST) vs. Temperature Figure 10. Startup Current vs. VDD Voltage 2.5 1.00 2.0 0.98 VIN-ON (V) VIN-OFF (V) 5 SG6846WA — Highly Integrated Green-Mode PWM Controller Typical Performance Characteristics 1.5 1.0 0.5 0.96 0.94 0.92 0.90 0.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -24 -7 10 26 43 59 76 92 109 125 Temperature (℃) Temperature (℃) Figure 11. PWM Turn-off Threshold Voltage (VIN-OFF) vs. Temperature © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 Figure 12. PWM Turn-on Threshold Voltage (VIN-ON) vs. Temperature www.fairchildsemi.com 8 70 80 56 PWM Frequency (kHz) f OSC (kHz) 85 75 70 65 60 -40 -25 -10 5 20 35 50 65 80 95 110125 42 28 14 0 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 VFB (V) Temperature (°C) Figure 13. Normal PWM Frequency (fOSC) vs. Temperature Figure 14. PWM Frequency vs. FB Voltage 0.90 0.90 0.85 0.82 0.74 0.75 VTH-O (V) VTH-P (V) 0.80 0.70 0.65 0.66 0.58 0.50 0.60 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 VIN (V) VIN ( V ) Figure 15. Current-Limit Threshold vs. VIN Voltage Figure 16. 2/3 Current-Limit Threshold vs. VIN Voltage 71.0 1.4 70.5 1.2 70.0 1.0 VRTTH (V) IRT (µA) SG6846WA — Highly Integrated Green-Mode PWM Controller Typical Performance Characteristics (Continued) 69.5 69.0 0.8 0.6 0.4 68.5 -40 -25 -10 5 -40 -25 -10 5 20 35 50 65 80 95 110125 Temperature (℃ ) Temperature (℃) Figure 17. Output Current of RT Pin (IRT) vs. Temperature © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 20 35 50 65 80 95 110 125 Figure 18. FB Output High Voltage (VRTTH) vs. Temperature www.fairchildsemi.com 9 This two-level OCP protection and up/down counter are especially designed for SMPS with surge current output, such as those for printers, scanners, and motor drivers. Startup Operation The turn-on and turn-off thresholds are fixed internally at 16.5V and 10.5V, respectively. To enable the SG6846WA during startup, the hold-up capacitor must first be charged to 16.5V through the startup resistor. Constant Output Power Limit For constant output power limit over universal inputvoltage 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 generates a higher VIN voltage. The threshold voltage decreases as VIN increases (shown in Figure 19), making the maximum output power at high-line input voltage equal to that at low-line input. The hold-up capacitor continues 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 startup process. The hold-up capacitor must supply VDD sufficient energy that avoid voltage drop to UVLO during startup. A typical startup current is only 15µA; which allows use of a high-resistance, low-wattage startup resistor. A 1.5MΩ/0.25W startup resistor and a 10µF/25V VDD holdup capacitor are sufficient for a universal input range. The required operating current has been reduced to 3.7mA, which 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 is completely turned off and the power supply enters burst-mode. This green mode dramatically reduces power consumption under light-load and zero-load conditions. Figure 19. Linearly Current Limit Curve 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 than 0.7V, the PWM output is shut off. If the VIN is over 0.9V, the PWM output is turned on again. The hysteresis window for on/off is ~0.2V. Oscillator Operation A resistor connected from the RI pin to GND pin generates a reference current source inside the SG6846WA, which is used to determine the PWM frequency. Increasing the resistance decreases the amplitude of the current source and reduces the PWM frequency. Using a 26kΩ resistor results in a corresponding 65kHz switching frequency. The relationship between RI and the switching frequency is: fPWM(kHz) = 1690 RI (kΩ ) VDD Over-Voltage Protection (OVP) VDD over-voltage protection is built in to prevent damage. If VDD is over 24V, SG6846WA is latched off. Over-Temperature Protection (OTP) An external NTC thermistor can be connected from the RT pin to GND. The impedance of the NTC decreases at high temperatures. When the voltage of the RT pin drops below 1.065V, the SG6846WA is turned off after tDOTP-LATCH. If RT pin is not connected to NTC resistor to do Over-Temperature Protection (OTP), it is recommended to place one 100KΩ resistor to ground to prevent from noise interference. This pin is limited by internal clamping circuit. (2) If an open-circuit or short-circuit to ground occurs at the RI pin, the internal protection circuit immediately shuts down the controller. Two-Level Over-Current Protection (OCP) The cycle-by-cycle current limiting shuts down the PWM immediately when the switching current is over the peak-current threshold. Additionally, when the switching current is higher than the over-current threshold, the internal counter counts down. When the total accumulated counting time is more than around 1700ms (RI = 26kΩ), the controller is latched off and the internal counter counts up. When the switching current is lower than the over-current threshold, the internal counter counts down. When the total accumulated counting time is more than ~1700ms (RI = 26kΩ), the controller is latched off. © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.1 SG6846WA — Highly Integrated Green-Mode PWM Controller Operation Description Noise Immunity 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. Avoid long PCB traces and component leads. Compensation and filter components should be located near the SG6846W. www.fairchildsemi.com 10 R16 D4 4 1 5 2 7 1 9 3 11 C11 12 2 P16V P16V L2 1 2 C17+ C14 + 16V 16V C15 + 1 3 2 2 R11 C5 1 C3 2 R17 2 2 + 32V 1 2 D3 L4 21 + 32V C13 + 2 1 D1 1 R4 C12 + 10 D2 R9 R3 2 2 6 1 C2 3 2 R2 C16+ 3 R12 C4 1 P7 13 1 + R8 R1 P32V P32V L1 1 2 CX2 4 3 1 P2 TX1 1 VZ1 LF1 CY2 BD1 1 CX1LF2 3 4 2 CY1 1 RT1 2 F1 t P1 2 U1 FB 2 1 Q1 R13 8 1 2 GATE FB VDD VIN SENSE 7 L3 R6 6 1 2 3 C1 GND 3 1 1 D5 + R5 4 RI RT 5 R10 C6 R14 NTC1 R7 P16V P16V 1 4 R15 FB P16V FB C7 R18 K 2 3 U2 P32V P16V C9 P32V R19 R20 R R21 A U3 Figure 20. Application Circuit for 32V / 16V Output Table 1. Bill of Materials Part No. Value Part No. Value Part No. Value R1, R2, R3, R4 470KΩ ±5% C4 103P 630V D3 FR103 1.0A 200V R8, R9 S1MΩ ±1% C10,C11 102P 1KV BD1 DBL406G R5 16K2Ω ±1% C6,C7 102P 50V D4 BYT28-300 R15 1K5Ω ±5% C9 222P 50V D5 BYV32-150 R13 10Ω ±5% C14,C17 470µF 25V F1 250V4A QUICK R18 4K7Ω ±5% C15 220µF 25V L1,L2 1.8µH R21 15KΩ ±1% C13,C16 220µF 50V L4 10µH R7 27KΩ ±5% C2 150µF 400V U3 TL431 ±1% R6 330Ω ±1% C1 4.7µF 50V U1 SG 6846 R19 102KΩ ±1% C3 10µF 50V U2 PC817 R14 0Ω22 ±5% CX1 X1 0.47µF 275V Q1 7NB60 R16, R17 1W 20Ω ±5% C8 Y2 222P 250V TX1 EI-33 R11 20KΩ ±5% C5 100µF 50V RT1 SCK053 R12 100KΩ ±5% CX2 X2 0.1µF 275V VZ1 14ψ 470V R20 887KΩ ±1% D1 1N4148 R22 10KΩ ±1% D2 BYV95C © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.2 SG6846WA — Highly Integrated Green-Mode PWM Controller Reference Circuit www.fairchildsemi.com 11 5.00 4.80 A 0.65 3.81 5 8 B 6.20 5.80 PIN ONE INDICATOR 1.75 4.00 3.80 1 5.60 4 1.27 (0.33) 0.25 M 1.27 C B A LAND PATTERN RECOMMENDATION 0.25 0.10 SEE DETAIL A 1.75 MAX 0.25 0.19 C 0.10 0.51 0.33 0.50 x 45° 0.25 R0.10 SG6846WA — Highly Integrated Green-Mode PWM Controller Physical Dimensions C OPTION A - BEVEL EDGE GAGE PLANE R0.10 OPTION B - NO BEVEL EDGE 0.36 NOTES: UNLESS OTHERWISE SPECIFIED 8° 0° 0.90 0.406 A) THIS PACKAGE CONFORMS TO JEDEC MS-012, VARIATION AA, ISSUE C, B) ALL DIMENSIONS ARE IN MILLIMETERS. C) DIMENSIONS DO NOT INCLUDE MOLD FLASH OR BURRS. D) LANDPATTERN STANDARD: SOIC127P600X175-8M. E) DRAWING FILENAME: M08AREV13 SEATING PLANE (1.04) DETAIL A SCALE: 2:1 Figure 21. 8-Pin, SOIC,JEDEC MS-012, .150-inch Narrow Body Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/. © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.2 www.fairchildsemi.com 12 SG6846WA — Highly Integrated Green-Mode PWM Controller © 2012 Fairchild Semiconductor Corporation SG6846WA • Rev. 1.0.2 www.fairchildsemi.com 13