Vol.02-06-e / June2002 MR2000 Series Standby Compatible Partial Resonance Power Supply IC Module with High-speed IGBT Shigeru Hisada - Electronic Device Div.Group Advanced Power Products Div. Device Design Dept. (Joined the company in 1991) 1 Introduction Development of the MR2000 Series Energy conservation guidelines from the Ministry of Economy, Trade and Industry require a reduction in the standby power consumption of various types of electrical products as a means of reducing environmental CO 2 levels. There are strong demands for reduced power consumption in common devices such as TVs and set top boxes (STB) which remain on standby for long periods of time, and efficient operation under micro-loads is required. Furthermore, demands for integration of the various protective functions, higher functionality, and lower price are increasing to the extent that it is now difficult to satisfy such demands with existing products. In response, a Multi Chip Module (MCM) structure, incorporating only a main switch and control IC, has been adopted in the development of the MR2000 Series of highly functional and low-cost IC modules. 2 Outline The MR2000 Series includes the 100V input and 200V/worldwide input IC modules, with a function for burst mode switching under micro-load. The 100V input MR2500 Series employs a 500V resistant MOSFET, while the 200V/worldwide input MR2900 Series employs a newly developed 900V resistant high-speed IGBT and a switching device optimized for the various input ranges. Both devices are partial resonance power supply IC modules comprising a low power consumption control IC as the control circuit. MR2000 Series modules are contained in a fully molded MA Series package as used for previous power supply hybrid ICs with an added screw hole. Password Vol.02-06-e MR2000 Series P.01 All Rights Reserved Copyright (C) SHINDENGEN ELECTRIC MANUFACTURING CO., LTD. 2002 2-1 Primary Features 1 Current consumption is reduced with use of the burst mode, promoting standby compatibility with a single converter. 2 The optimized switching device provides ideal partial resonance operation for high efficiency and low noise. 3 The 900V resistant switching device (high-speed IGBT) simplifies design of power supplies for worldwide input. 4 Power consumption under micro-load is extremely low (burst mode). 5 Use of a drain kick circuit eliminates the need for a start-up resistor. 6 The use of a soft drive circuit reduces noise. 7 Incorporates an over-current protection function (primary current detect, Ton limit). 8 Incorporates over-voltage protection and thermal shutdown functions. 9 A power supply circuit may be configured with the minimum of external components. 10 The use of the fully molded package is beneficial for insulation design. 2-2 Product Lineup O u t p u t c a p a c i t y P o [ W ] (r e f e r e n c e va l u e s ) Model MR2520 Main switch MOSFET MR2540 MR2920 MR2940 High-speed IGBT Peak input voltage 500 900 Peak input current Input voltage range Input voltage range Input voltage range AC90~132V AC90~276V AC180~276V 8 100 - - 13 150 - - 7 - 100 150 10 - 150 225 Table 1 MR2000 Series Product Lineup Password Vol.02-06-e MR2000 Series P.02 All Rights Reserved Copyright (C) SHINDENGEN ELECTRIC MANUFACTURING CO., LTD. 2002 2-3 7 Equivalent Circuit and Appearance Drain/Collector Z/C F/B Q1 GND IC1 Vcc Vin 1 2 3 4 5 6 Source/Emitter Fig.1 Equivalent Circuit 3 Fig.2 Appearance Features 3-1 Main Switching Device - High-speed IGBT (MR2900 Series) The unique (patented) structure of the Shindengen high-speed IGBT provides both high-speed switching and low saturation voltage in a single device, thus also permitting its use in switching power supplies. This newly developed high-speed IGBT is positioned between the MOSFET and the bipolar transistor (Fig.3). Fig.4 shows a comparison of losses in the 900V resistant switching device in the worldwide partial resonance power supply. The loss curve is comparatively flat in relation to the wide range of input voltage, and as such the device is optimized for use with a variety of international input voltages. Device Symbol Drive MOSFET Voltage High-speed IGBT Voltage IGBT Voltage BJT Current ON loss Switching loss Large Small Small Large Fig.3 Comparison of Switching Devices Password Vol.02-06-e MR2000 Series P.03 All Rights Reserved Copyright (C) SHINDENGEN ELECTRIC MANUFACTURING CO., LTD. 2002 Main switch losses P [W] Bipolar transistor High-speed IGBT 100V MOSFET 200V 300V AC input voltage Vin [V] Fig.4 Comparison of Losses in 900V Resistant Switching Device 3-2 Advantages of 900V Resistance in the High-speed IGBT (MR2900 Series) The MR2900 Series incorporates a 900V resistant high-speed IGBT for almost ideal partial resonance operation. Fig.5 shows a comparison between waveforms with 650V and 900V resistance. The use of the 900V resistant device allows a sufficiently small resonance condenser discharge current, with consequently reduced switching losses. This in turn allows an increase in the capacity of the resonance condenser C1, thus allowing lower noise and a power supply of higher efficiency. The ability to maintain a sufficient margin of voltages resistance eliminates the need for a DCR snubber circuit, thus reducing the number of components required and allowing design of power supplies with superior cost-performance. 800 700 600 Voltage [V] Current [A] 900V design 650V design 6 5 4 500 3 400 2 300 1 200 Small switching loss 0 100 / 0 . Fig.5 Comparison between Waveforms with 650V and 900V Resistance Password Vol.02-06-e MR2000 Series P.04 All Rights Reserved Copyright (C) SHINDENGEN ELECTRIC MANUFACTURING CO., LTD. 2002 Unnecessary A/ Discharge current reduced Fig.6 Resonance Condenser Discharge Current at ON 3-3 Protection Circuits 1 Load-Shorting Protection Inclusion of a load current reduction circuit enables reduction in heating under load and alleviates stress on the device. 2 Protection Against Malfunction at ON The Leading Edge Blank (LEB) prevents malfunctions in the over-current detect circuit due to discharge current in the partial resonance condenser at ON. 3 Protection Against Malfunction at OFF Inclusion of the ON-dead timer prevents malfunctions at OFF. This function ensures that resonant oscillation due to the leakage inductance and the resonance condenser at OFF, are recognized as trigger signals, and trigger input is then masked to prevent switching ON again. 4 Over-current Protection Over-current protection for the device consists of pulse-by-pulse over-current protection to detect primary current, and a limitation on the ON width. Password Vol.02-06-e MR2000 Series P.05 All Rights Reserved Copyright (C) SHINDENGEN ELECTRIC MANUFACTURING CO., LTD. 2002 5 Latch Halt Function for Over-voltage Protection 6 Thermal Shutdown (TSD) to Halt Latch at Overheating The onboard protection circuits described above reduce the number of components required and thus simplify design. 3-4 Standby Function The standby mode is selected by simply dropping the voltage at the Z/C ((1) pin) to 3.5V or less. The MR2000 Series supports an ideal standby mode employing a method developed by Shindengen based on the use of small intermittent output ripples. Fig.7 and Fig.8 show the input voltage Pin, and the waveform at Po = 1.1W (11V, 0.1A), for a worldwide input Po = 100W power supply for TV applications. Standby Po - Pin Input voltage Pin [W] 2.5 2 1.5 1 AC110V 0.5 0 AC230V 0 0.5 1 1.5 Output voltage Po [W] Fig.7 Input Voltage in Standby Mode Vo:2V/DIV VCE:200V/DIV ğ0V ICE:1A/DIV ğ0A s/DIV TimeBase:500 Fig.8 Waveform in Standby Mode Password Vol.02-06-e MR2000 Series P.06 All Rights Reserved Copyright (C) SHINDENGEN ELECTRIC MANUFACTURING CO., LTD. 2002 3-5 Simple Design The functions described above considerable simplify design of peripheral circuits. Collector current detect resistor, a maximum ON width setting resistor, and adjustment with three or four ON timing CRs is sufficient for basic design. With worldwide input, the F/B pin ON width control is used to add a droop compensation circuit. The table below describes the name and the function of each pin. Pin number Pin name 1 Z/C Set ON timing. The signal from the control coil is set with the CR time constant. The burst mode is selected by connecting a photocoupler to the Z/C pin. 2 F/B Controls ON width with pin voltage. A resistor to set the maximum ON width, and a feedback photocoupler, are connected to this pin. 3 GND GND pin 4 Vcc Supplies power from the control coil. Vin The AC voltage rectified in the start-up circuit is input directly. Current is supplied to Vcc only at start-up, and is automatically decoupled following start-up. 5 6 7 Function Emitter/OCL Current detect resistor connected to emitter (source)/OCL pin. Collector Main switch collector (drain) pin Items in brackets refer to MR2500 Series. Table 2 Pin Names and Functions 4 Conclusion This article has introduced the features of an IC module which is both compatible with worldwide input, and supports burst mode switching under micro-load. The MR2000 Series is a high-functionality and low-cost IC module developed through a program of joint research between the Shindengen Semiconductor Division and the Functional Devices Division. As such, it is optimized for control ICs as well as main switching devices in partial resonance power supplies. Its characteristics permit high efficiency, low noise, and low cost over a wide range of markets in such electronic products as TVs, CRT and TFT monitors, STBs, and DVDs, as well as in a variety of office automation equipment. Further development in terms of applications, and development of new models to suit market requirements, is scheduled. Password Vol.02-06-e MR2000 Series P.07 All Rights Reserved Copyright (C) SHINDENGEN ELECTRIC MANUFACTURING CO., LTD. 2002