SG6859DZ资料

Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 FEATURES 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 󰂄 Green-Mode PWM Supports the “Blue Angel” Standard Low Start-up Current (9uA) Low Operating Current (3mA) Leading-Edge Blanking Constant Output Power Limit Universal Input Built-in Synchronized Slope Compensation Current Mode Operation Cycle-by-cycle Current Limiting Under Voltage Lockout (UVLO) Programmable PWM Frequency with Frequency Hopping VDD Over Voltage Protection (Auto Restart) Gate Output Voltage Clamped at 17V Low Cost Few External Components Required Small SOT-26 and Dip 8 Packages DESCRIPTION This highly integrated PWM controller provides several special enhancements designed to meet the low standby-power needs of low-power SMPS. To minimize standby power consumption, the proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load conditions. This green-mode function enables the power supply to easily meet even the strictest power conservation requirements. The BiCMOS fabrication process enables reducing the start-up current to 9uA, and the operating current to 3mA. To further improve power conservation, a large start-up resistance can be used. Built-in synchronized slope compensation ensures the stability of peak current mode control. Proprietary internal compensation provides a constant output power limit over a universal AC input range (90VAC to 2VAC). Pulse-by-pulse current limiting ensures safe operation even during short-circuits. To protect the external power MOSFET from being damaged by supply over voltage, the SG6859’s output driver is clamped at 17V. SG6859 controllers can be used to improve the performance and reduce the production cost of power supplies. The SG6859 is the best choice for replacing linear and RCC-mode power adapters. It is available in 8-pin DIP and 6-pin SOT-26 packages. APPLICATIONS General-purpose switching mode power supplies and flyback power converters, such as 󰂄 Battery chargers for cellular phones, cordless phones, PDAs, digital cameras, and power tools 󰂄 Power adapters for ink jet printers, video game consoles, and portable audio players 󰂄 Open-frame SMPS for TV/DVD standby and other auxiliary supplies, home appliances, and consumer electronics 󰂄 Replacements for linear transformers and RCC SMPS 󰂄 PC 5V standby power. TYPICAL APPLICATION SG6859 © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification MARKING DIAGRAMS PIN CONFIGURATION ORDERING INFORMATION Part Number SG6859TZ SG6859DZ AAJMW AAJ: SG6859 M: Mask Version W: Week code A~Z=W1~W26 A~Z=W27~W52 : Lead Free Package SOT-26 GND FBRIDIP-8 GATE VDD SENSE XXXXXXXXYWWV SG6859TP T: D=DIP P: Z =Lead Free Null=Regular Package XXXXXXXX: Wafer Lot Y: Year; WW: Week V: Assembly Location GATEVDDNCSENSEGND FB NC RI Pb-Free Package 6-Pin SOT-26 8-Pin DIP-8 PIN DESCRIPTIONS Name GATE VDD Pin No. DIP-8(SOT-26) 1 / (6) 2 / (5) Type Function Driver Output Supply The totem-pole output driver for driving the power MOSFET. Power supply. NC pin. Current sense. This pin senses the voltage across a resistor. When the voltage reaches the internal threshold, PWM output is disabled. This activates over-current protection. This pin also provides current amplitude information for current-mode control. A resistor connected from the RI pin to ground will generate a constant current source for the SG6859. This current is used to charge an internal capacitor, to determine the switching frequency. Increasing the resistance will reduce the amplitude of the current source and reduce the switching frequency. A 95kΩ resistor Ri results in a 50uA constant current Ii and a 70kHz switching frequency.NC pin. Feedback. The FB pin provides the output voltage regulation signal. It provides feedback to the internal PWM comparator, so that the PWM comparator can control the duty cycle. Ground. NC 3 SENSE 4 / (4) Analog Input RI 5 / (3) Analog Input/Output NC 6 FB GND 7 / (2) 8 / (1) Analog Input Supply © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification

BLOCK DIAGRAM

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification ABSOLUTE MAXIMUM RATINGS Symbol Parameter VVDD VFB VSENCE TJ RθJA TSTG TL VESD-HBM VESD-MM DC Supply Voltage * Input Voltage to FB Pin Input Voltage to Sense Pin Operating Junction Temperature Thermal Resistance (Junction to Air) Storage Temperature Range Lead Temperature (Wave soldering or IR, 10 seconds) ESD Capability, HBM Model ESD Capability, Machine Model Value 30 -0.3 to 7 -0.3 to 7 150 Unit V V V °C SOT 208.4 °C/W DIP 82.5 °C/W -55 to +150 260 3.5 200 °C °C kV V * 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 CONDITIONS Symbol Parameter VDD DC Supply Voltage TA Operating Ambient Temperature * For proper operation. Value -20 to +85 Unit °C ≦22 V ELECTRICAL CHARACTERISTICS (VDD = 15V; TA = 25°C) VDD Section Symbol Parameter VDD-OP VDD-ON VDD-OFF IDD-ST Continuously Operation Voltage Turn-On Threshold Voltage Turn-Off Threshold Voltage Startup Current Test Condition VDD=VDD-ON – 0.1V VDD=15V, GATE with 1nF to GND (Auto Restart) Min. Typ. Max. Unit 15.5 10.5 16.5 11.5 9 22 17.5 12.5 15 V V V µA IDD-OP Operating Supply Current VDD-OVP tD-VDDOVP VDD-G OFF VDD Over-voltage-protection level VDD Low-threshold Voltage to Exit Green-off Mode 3 3.5 mA 24 25 125 26 V µs V VDD Over-voltage-protection Debounce(Auto Restart) VDD-OFF + 1 © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification Feedback Input Section Symbol Parameter ZFB Input Impedance VFB-OPEN VFB-OL tD-OLP VFB-N VFB-G SG FB Output High Voltage FB Open-loop Trigger Level ===Test Condition Min. Typ. Max. Unit = 5 KΩ = 5 V 4.3 2.6 4.6 56 2.85 2.20 4.9 3.1 V ms V V The delay time of FB pin Open Loop Protection Green-Mode Entry FB Voltage Green-Mode Ending FB Voltage Green-Mode Modulation Slope RI=95KΩ 40 75 100 Hz/mV Current Sense Section Symbol Parameter ZSENSE Input Impedance tPD VSTHFL VSTHVA tLEB DCYSAW Delay to Output Flat Threshold Voltage for Current Limit Valley Threshold Voltage for Current Limit Leading-Edge Blanking Time Duty Cycle of SAW Limit Test Condition Min. Typ. Max. Unit 10 KΩ 40 0.91 0.75 250 55 0.96 0.80 300 40 100 1.01 0.85 350 ns V V ns % Oscillator Section Symbol Parameter FOSC Normal PWM Frequency Center Frequency Hopping Range Test Condition Min. Typ. Max. Unit RI=95KΩ 65 70 75 KHz ±4.9 THOP Hopping Period FOSC-G FDV FDT Green-Mode Frequency Frequency Variation versus VDD Deviation Frequency Variation versus Temp. Deviation RI=95KΩ 3.7 ms RI=95KΩ 22 KHz VDD=13.5 to 22V TA=-20 to 85°C 0 0.02 2 2 % % Output Section Symbol Parameter DCYMAX Maximum Duty Cycle VGATE-L Output Voltage Low VGATE-H Output Voltage High tr Rising Time tf Falling Time VGATE-CLAMP Output Clamp Voltage Test Condition Min. Typ. Max. Unit 70 75 80 % V ns ns VDD=15V, Io20mA VDD=13.5V, Io20mA 8 VDD=15V, CL1nF VDD=15V, CL1nF 1.5 V 150 55 VDD22V 16 17 18 V © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification TYPICAL CHARACTERISTICS Turn-On Threshold Voltage (VDD-ON) vs Temperature17.0141312111098 Turn-Off Threshold Voltage (VDD-OFF) vs Temperature16.816.616.416.216.0-40-25-105203550658095110125VDD-OFF (V)VDD-ON (V)-40-25-105203550658095110125Temperature (℃)Temperature (℃) Startup Current (IDD-ST) vs Temperature1.41.21.00.80.60.40.2-40-25-105203550658095110125 Operating Supply Current (IDD-OP) vs Temperature3.02.8IDD-OP (mA)IDD-ST (uA)2.62.42.22.0-40-25-105203550658095110125Temperature (℃)Temperature (℃) Normal PWM Frequency (FOSC) vs Temperature72.0 Maximum Duty Cycle (DCYMAX) vs Temperature75.074.871.5DCYMAX (%)FOSC (Khz)74.671.074.470.574.270.0-40-25-10520355065809511012574.0-40-25-105203550658095110125Temperature (℃)Temperature (℃) © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Green-Mode Entry FB Voltage (VFB-N) vs Temperature3.22.30 Product Specification Green-Mode Ending FB Voltage (VFB-G) vs Temperature3.02.28VFB-N (V)2.6VFB-G (V)-40-25-1052035506580951101252.82.262.242.42.222.22.20-40-25-105203550658095110125Temperature (℃)Temperature (℃) Leading-Edge Blanking Time (tLEB) vs Temperature340330 Operating Supply Current vs VDD voltage3.53.0IDD-OP (mA)-40-25-105203550658095110125320tLEB (ns)2.53103002902802.01.51.012131415161718192021222324Temperature (℃)VDD (V) © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Each time the power MOSFET is switched on, a

OPERATION DESCRIPTION turn-on spike will inevitably occur at the sense-resistor.

To avoid premature termination of the switching pulse, a

SG6859 devices integrate many useful designs into

320nsec leading edge blanking time is built in.

one controller for low-power switch-mode power supplies.

Conventional RC filtering can therefore be omitted.

The following descriptions highlight some of the features

During this blanking period, the current-limit comparator

of the SG6859 series.

is disabled and it cannot switch off the gate driver.

Product Specification

Start-up Current

The start-up current is only 9uA. Low start-up current allows a start-up resistor with a high resistance and a low-wattage to supply the start-up power for the controller. A 1.5 MΩ, 0.25W, start-up resistor and a 10uF/25V VDD hold-up capacitor would be sufficient for an AC-to-DC power adapter with a wide input range (100VAC to 240VAC).

Constant Output Power Limit

When the SENSE voltage across the sense resistor Rs reaches the threshold voltage (around 0.96V), the output GATE drive will be turned off following a short propagation delay tPD.

This propagation delay will introduce an additional current proportional to tPD*Vin/Lp. The propagation delay is nearly constant regardless of the input line voltage VIN. Higher input line voltages will result in larger additional currents. At high input line voltages, the output power limit will be higher than at low input line voltages. To compensate for this output power limit variation across a wide AC input range, the threshold voltage is adjusted by adding a positive ramp.

This ramp signal rises from 0.80V to 0.96V, and then flattens out at 0.96V. A smaller threshold voltage forces the output GATE drive to terminate earlier.

This reduces the total PWM turn-on time and makes the output power equal to that of low line input. This proprietary internal compensation ensures a constant output power limit for a wide AC input voltage range (90VAC to 2VAC).

Operating Current

The operating current has been reduced to 3mA. The low operating current results in higher efficiency and reduces the VDD hold-up capacitance requirement.

Green-Mode Operation

The proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load conditions. On-time is limited to provide stronger protection against brownouts and other abnormal conditions. The feedback current, which is sampled from the voltage feedback loop, is taken as the reference. Once the feedback current exceeds the threshold current, the switching frequency starts to decrease. This green-mode function dramatically reduces power consumption under light-load and zero-load conditions. Power supplies using the SG6859 can easily meet even the strictest regulations regarding standby power consumption.

Under Voltage Lockout (UVLO)

The turn-on and turn-off thresholds of the SG6859 are fixed internally at 16.5V/11.5V. During start-up, the hold-up capacitor must be charged to 16.5V through the start-up resistor, so that the SG6859 will be enabled. The hold-up capacitor will continue to supply VDD until power can be delivered from the auxiliary winding of the main transformer. VDD must not drop below 11.5V during this start-up process. This UVLO hysteresis window ensures that hold-up capacitor will be adequate to supply VDD during start-up.

Oscillator Operation

A resistor connected from the RI pin to ground will generate a constant current source for the SG6859. This current is used to charge an internal capacitor. The charge-time determines the internal clock speed and the switching frequency. Increasing the resistance will reduce the amplitude of the input current and reduce the switching frequency. A 95kΩ resistor Ri results in a 50uA constant current Ii and a 70kHz switching frequency. The relationship between Ri and the switching frequency is:

fPWM =

6650RI (kΩ)

(kHz)

Leading-Edge Blanking

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Gate Output

Low Cost Green-Mode PWM Controller for Flyback Converters SG6859

Product Specification

The SG6859 BiCMOS output stage is a fast totem pole gate driver. Cross conduction has been avoided to minimize heat dissipation, increase efficiency, and enhance reliability. The output driver is clamped by an internal 17V Zener diode in order to protect power MOSFET transistors against undesired over-voltage gate signals.

Built-in Slope Compensation

The sensed voltage across the current sense resistor is used for current mode control and pulse-by-pulse current limiting. Built-in slope compensation will improve stability and prevent sub-harmonic oscillations due to peak-current mode control. The SG6859 has a synchronized, positively-sloped ramp built-in at each switching cycle. The slope of the ramp is:

0.36×Duty

Duty(max.)

Noise Immunity

Noise from the current sense or the control signal can cause significant pulse width jitter, particularly in continuous-conduction mode. While slope compensation helps alleviate these problems, further precautions should still be taken. Good placement and layout practices should be followed. Avoiding long PCB traces and component leads, locating compensation and filter components near the SG6859, and increasing the power MOS gate resistance is advised.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification REFERENCE CIRCUIT 1LF1BD1C3CX1R124C1C2R531NR2R4109D1U1123C6R9C11R6GNDGATEFBRIVDDSENSE6R15285Q1373,42GND2R10C7C8D5C91T11,22D4L2112VOR31L12R71R8C41D22R11R134U2R1432C103U31R122CY1 BOM Reference Component BD1 BD 1A/500V CX1 (Optional) XC 0.1uF CY1 (Optional) YC 102P/400V (Y1) C1 C2 C3 C4 C6 C8 C9 C10 C11 D1 D2 CC 103P/500V EC 10µF/400V 105°C CC 102P/500V EC 10µ/50V CC 472P 0805 EC 470µ/10V 105°C EC 220µ/10V 105°C CC 222P 0805 N.C. Diode FRI07 Diode FR102 Reference Component L2 Q1 R1,R2 R3,R4 R5 R6 R7 R8 R9 R11 R12 R13 R14 R15 U1 U2 U3 10uH 6mm MOSFET 1A/600V R 750KΩ 1206 R 47KΩ 1206 R 47Ω 1206 R 4.7Ω 1206 R 100Ω 0805 R 10Ω 1206 R 100KΩ 0805 R 100Ω 1/8W R 33KΩ 0805 R 33KΩ 1/8W R 4.7KΩ 0805 R 0Ω 0805 IC SG6859 PC817 TL431 C7 (Optional) CC 102P/100V 1206 R10 (Optional) R 10Ω 1206 D4 Diode SB360 D5 (Optional) ZD 6.8V 0.5W F1 R 1Ω/0.5W L1 20mH 6*8mm T1 EE-16 © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification PACKAGE INFORMATION 8 PINS - DIP (D) D85Θ¢XE1EeB14A1A2Lb1beDimensions Symbol Millimeters Inches Min. Typ. Max. Min. Typ. Max. 0.015 A 5.334 0.210 A1 0.381 A2 3.175 3.302 3.429 0.125 0.130 0.135 b 1.524 0.060 b1 0.457 0.018 D E1 L eB θ˚ 9.017 9.271 10.160 0.355 0.365 0.400 6.223 6.350 6.477 0.245 0.250 0.255 2.921 3.302 3.810 0.115 0.130 0.150 8.509 9.017 9.525 0.335 0.355 0.375 0˚ 7˚ 15˚ 0˚ 7˚ 15˚ E 7.620 0.300 e 2.0 0.100 © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification 6 PINS - SOT (T) DbDetail AE1E1e1e3c1RA2ALA1L11Detail ADimensions Symbol Millimeters Inches Min. Typ. Max. Min. Typ. Max. A 1.45 0.057 A1 0.15 0.006 A2 0.90 1.15 1.30 0.036 0.045 0.051 b 0.30 0.50 0.011 0.020 c 0.08 0.22 0.003 0.009 D 2.90 0.114 E 2.80 0.110 E1 1.60 0.063 e 0.95 0.037 e1 1.90 0.075 L 0.30 0.45 0.60 0.020 0.018 0.024 L1 0.60 0.024 L2 0.25 0.010 R 0.10 0.004 R1 0.10 θ° θ1° 0° 4° 0.25 0.004 8° 0° 4° 0.010 8° 5° 10° 15° 5° 10° 15° © System General Corp.

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Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Product Specification

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