SG6841中文资料

Bb s .C hi n ad z.C omOPERATION DESCRIPTION Start-up currentTypical start-up current is only 30uA so that a high resistance, and low-wattage, start-up resistor can be used to minimize power loss. For an AC/DC adapter with universal input range, a 1.5 M Ω, 0.25W, start-up resistor and a 10uF/25V VDD hold-up capacitor are enough for this application.Operating currentOperating current has been reduced to 3mA. The low operating current enables a better efficiency and reduces the requirement of VDD hold-up capacitance.Green Mode OperationThe patented green-mode function provides an off-time modulation to reduce the switching frequency in the light load and no load conditions. The on time is limited for better abnormal or brownout protection. V FB , which is derived from the voltage feedback loop, is taken as the reference. Once V FB is lower than the threshold voltage, switching frequency will be linearly decreased to the minimum green mode frequency around 10kHz (R i =26k Ω).Oscillator OperationA resistor from RI pin to ground will generate a constant current source for SG6841. This current is used to charge an internal capacitor and hence the internal clock and switching frequency are determined. Increase the resistance will decrease the current source and reduce the switching frequency. A 26k Ω resistor R i creates a 50uA constant current I i and generates 65kHz switching frequency. The relation between Ri and switching freauency is:)(kHz )(k R 1690 I PWM f Ω=---------------------------- (1)The range of the PWM oscillation frequency is designed as 50kHz ~ 90kHz.Current sensing and PWM current limitingPeak current mode control is utilized in SG6841 to regulate output voltage and provide pulse by pulse current limiting. The switch current is detected by a sense resistor into the sense pin of SG6841. The PWM duty cycle is determined by this current sense signal and V FB , the feedback voltage. When the voltage on sense pin reaches V COMP = (V FB –1.0)/3, a switch cycle will be terminated immediately. V COMP is internally clamped to a variable voltage around 0.85v for output power limit.Leading Edge BlankingEach time when the power MOSFET is switched on,a turn-on spike will inevitably occur on the sense-resistor. To avoid premature termination of the switching pulse, a 270 nsec leading-edge blanking time is built in. Conventional RC filtering can therefore be omitted. During this blanking period, the current-limit comparator is disabled and it cannot switch off the gate driver.Under-voltage lockout (UVLO)The turn-on and turn-off threshold of SG6841 arefixed internally at 16V/10V. During start-up, the hold-up capacitor must be charged to 16V through the start-up resistor so that SG6841 will be enabled. The hold-up capacitor will continue to supply V DD before the energy can be delivered from auxiliary winding of the main transformer. V DD must not drop below 10V during this start-up process. This UVLO hysteresis window insures that hold-up capacitor is adequate to supply V DD during start-up.Gate Output / Soft DrivingThe SG6841 BiCMOS output stage is a fast totem pole gate driver. Cross conduction has been avoided to minimize heat dissipation, increases efficiency and enhances reliability. The output driver is clamped by an internal 18V Zener diode in order to protect power MOSFET transistors against undesirable gate over voltage. A soft driving waveform is implemented to minimize EMI.B b s.Ch i na dz.Co mBuilt-in Slope CompensationThe 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 or prevent sub-harmonic oscillation of peak current mode control. SG6841 inserts a synchronized positive-going ramp at every switching cycle. Vs-comp = 0.33V.Constant Output Power LimitWhen the SENSE voltage, across the sense resistor Rs, reaches the threshold voltage, around 1.0V, the output GATE drive will be turned off after a small propagation delay t D. This propagation delay will introduce an additional current proportional to t D*Vin/Lp. Since the propagation delay is nearly constant regardless of the input line voltage V IN. Higher input line voltage will result in a larger additional current and hence the output power limit is also higher than that under low input line voltage. To compensate this variation for wide AC input range, the threshold voltage is adjusted by the V IN current. Since VIN pin is connected to the rectified input line voltage through the start-up resistor, a higher line voltage will generate higher V IN current into the VIN pin. The threshold voltage is decreased if the V IN current is increased. Smaller threshold voltage, forces the output GATE drive to terminate earlier, thus reduce the total PWM turn-on time and make the output power equal to that of low line input. This proprietary internal compensation ensures a constant output power limit for wide AC input voltage from 90VAC to 264VAC.Thermal ProtectionAn NTC thermistor Rntc in series with a resistor Ra can be connected from pin RT to ground. A constant current I RT is output from pin RT. The voltage on RT pin can be expressed as V RT = I RT × (Rntc + Ra) in which I RT = 2 x (1.3V / Ri).At high ambient temperature, Rntc will be smaller such that V RT will decrease. When V RT is less than 0.65V (V OTP,START), the PWM duty cycle will be decreased to lower the internal temperature of power supply. If the over heating situation still exists such that V RT decreases further to 0.62V (V OTP,STOP), the PWM will be completely turned off.Limited Power ControlEvery time when the output of power supply is shorted or over loaded, the FB voltage will increase. If the FB voltage is higher than a designed threshold, 4.2V, for longer than 31msec, the PWM output will then be turned off eternally. V DD, the supply voltage for SG6841, will decrease due to the supply current for SG6841. When V DD is lower than the turn-off threshold such as 10V, SG6841 will be totally shut down. Due to the start up resistor, V DD will be charged up to the turn-on threshold voltage 16V until SG6841 is enabled again. If the over loading condition still exists, above protection will take place repeatedly. This will prevent the power supply from being overheated under over loading condition.Noise immunityNoise on the current sense or control signal may cause significant pulse width jitter, particularly in the 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 to the SG6841, and increasing the power MOS gate resistance will always help.B b s.Ch i na dz.Co m DISCLAIMERSLIFE SUPPORTSystem 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 the 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. MILITARYSystem 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 CHANGESSystem 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.。

sg6848芯片工作原理SG6848芯片是一种常见的集成电路芯片，它具有广泛的应用领域。

本文将以人类视角，以真实的叙述方式，描述SG6848芯片的工作原理。

SG6848芯片的工作原理可以简单概括为输入信号经过处理后转化为输出信号。

具体来说，SG6848芯片内部包含了多个功能模块，每个模块都有特定的功能和工作原理。

SG6848芯片的输入端接收来自外部的信号。

这些信号可以是电流、电压、温度等各种类型的信号。

芯片通过内部的放大电路将输入信号进行放大，以便后续的处理。

接下来，SG6848芯片的处理模块开始工作。

这个模块主要负责对输入信号进行分析和处理。

它可以根据预设的算法和规则对输入信号进行滤波、放大、变换等操作。

处理模块通过内部的运算单元对输入信号进行计算和处理，以得到期望的输出结果。

在处理模块的工作完成后，SG6848芯片的输出端会产生相应的输出信号。

这些输出信号可以是数字信号、模拟信号或其他形式的信号，具体取决于芯片的设计和用途。

输出信号可以用于驱动外部设备、控制系统的运行或提供给其他电路进行进一步的处理和分析。

总的来说，SG6848芯片通过输入端接收信号，经过内部的处理模块进行处理，最终产生相应的输出信号。

它可以在各种电子设备中发挥重要的作用，如通信设备、家电、工控设备等。

虽然SG6848芯片的工作原理可能较为复杂，但它的应用却十分广泛。

在现代科技的推动下，SG6848芯片不断演进和发展，为人们的生活带来了便利和创新。

无论是在通信领域、家庭生活还是工业制造，SG6848芯片都发挥着重要的作用，推动着社会的进步和发展。

希望通过本文的描述，读者对SG6848芯片的工作原理有了更清晰的了解。

无论是从技术角度还是从应用角度，SG6848芯片都是一种非常重要的电子元器件，它不仅为各种电子设备的正常运行提供了支持，也为人们的生活带来了更多的便利和创新。

ELARA11 INSTALLATIONCAUTION:Any operation described in this section should be performed by a qualified technician only.1. Unpacking the autoclavea. Unpack the autoclave and inspect for mechanical damage.b. Observe packing method and retain packing materials until the unit has been inspected.c. Mechanical inspection involves checking for signs of physical damage such as: scratched panelsurfaces, broken knobs, etc.To avoid injuries, lifting and carrying of the autoclave should be done with two or more persons or by using a mechanical aid.2. Installation preparationsa. Check and verify that the counter carrying the autoclave is a rigid and leveled surface and cancarry a load of 225 lbs (102kg). Attention: The Elara11 is not designed for use on a standard slideout shelf. If it is necessary to use a slide out shelf, it must be tested and/or rated for 225 lb (102kg)or more.b. Check and verify that the counter dimensions are at least 22” wide x 24” deep (55cm x 63.5cm).c. Keep the back and the sides of the autoclave 2” (5 cm) away from the wall to allow ventilation .d. If placed in a cabinet, verify that the rear of the cabinet is open to allow ventilation.e. Insufficient space for ventilation will result in a failure of the vacuum portion of the cycle.f. It is recommended that enough space be left around the autoclave to give a technician access forservicing the machine.g. Check and verify that the room ventilation is 10 cycles per hour minimum.h. Check and verify that the ambient temperature range is 41°F - 104°F (5°C - 40°C); it is preferablenot to exceed 86°F (30°C).i. Check and verify that the ambient relative humidity does not exceed 85%.3. Connections to utility suppliesa. Check and verify that the power supply is a 1 phase, 230Vac (220 to 235 volts) 50/60Hz, 15Asupply. Failure to comply can result in poor performance and/or damage to the autoclave. Ifvoltage is below 220V or above 235V, a buck/boost transformer (0.5KVA) must be installed by alicensed electrician.b. Check and verify that the autoclave is connected to a separate power source to avoid flickers oflight or sensitive devices.c. Check and verify grounding of the autoclave.d. Check and verify that the electrical net is protected with a current leakage safety relay (GFI).e. At the time of installation, before the autoclave can be okayed for daily operation the followingchecks need to be made:1. The leakage current test.2. Test the operation of the current leakage safety relay (GFI).3. Ground Check: Test the continuity of the grounding connection.4. Operating the autoclavea. Plug the power cord into the power socket.b. Turn on the Main Switch/Circuit Breaker.c. Select the "Vacuum Test" cycle to keep the steam generator and heating elements from heatingup. (See Selecting a Program sec. 10.6 in the Operator’s Manual.)d. Open the door of the autoclave and remove the trays and the packaging material.e. Door check: Ensure that the door locking mechanism is functioning properly.f. Set clock and date. See Setting the Clock sec. 7.3 in the Operator’s Manual.g. Atmospheric Pressure check:This unit is set at the factory for 100 kpa; this is the atmospheric pressure at sea level. If the unit islocated more that 500 ft above or below sea level then the Atmospheric Pressure parameter mustbe set accordingly. See ATMPressure sec 7.2.7 in the Technicians Manual (or call TuttnauerTechnical Service at 800-624-5836).h. Fill the Mineral Free Water Reservoir with water meeting the quality specs, shown in the Operator’sManual sec. 4.10, as follows:i. Fill with 4 liters of mineral free water by pouring it into the mineral free water reservoir fillopening at the top of the machine (see front view in the Operator’s Manual).ii. Fill the remaining quantity by pouring water gently into the front water reservoir funnel until it reaches the required level on the water level sight gauge (See Front View in theOperator’s Manual).i. Insert a paper roll in the printer (see Printer Handling sec. 8.2 in the Operator’s Manual).j. Close the door and perform a Vacuum Test. If the test fails, perform another test since the fail may be a result of moisture in the air. If the second test fails it may be necessary to run Program 2 withthe long drying cycle to remove any excess moisture that is causing the test to fail.k. If the Vacuum Test is successful then select the B&D Test cycle. At this stage the chamber and steam generator will be heating up. It will take approximately 15 minutes (from selecting the B&DTest).l. While waiting for the unit to heat up explain and instruct the operator as follows (use the operation manual as reference):i. Operation principals of the autoclave.ii. Preparation for sterilizing instruction including loading instructions.iii. Intended use of each cycle.iv. Selecting a cycle.v. Water filling method.vi. Displayed error and operational messages.vii. Monitoring and changing parameters.viii. Printer handling.ix. Maintenance instructions.x. At this point the autoclave should have reached operating temperature and be ready to perform the B&D cycle. Perform a B&D test with a chemical indicator.xi. The operator should perform a cycle under supervision of the technician.After the above steps are performed, the autoclave is ready for daily use.。