Monolithic switching power supplies have the characteristics of high integration, high cost performance, simplest peripheral circuits, and optimal performance indicators, which have attracted more and more attention. At present, with the application of monolithic switching power supply modules, medium and small power switching power supplies are developing in the direction of short, small, light and thin. They can be widely used in instrumentation, computers, household appliances (such as color TVs, DVDs, digital cameras), automatic control and other fields, laying the foundation for the promotion and popularization of new high-efficiency and energy-saving power supplies. The development of various general, precision and special monolithic switching power supply modules can greatly improve the technological level of China's switching power supply products and their competitiveness in the domestic and foreign markets, creating huge economic and social benefits.
I: Overview of the development of monolithic switching power supplies [1]
In the mid- and late 1990s, with the development of integrated circuits, various types of monolithic switching power supply integrated circuits appeared. It integrates the pulse width controller, power output stage, protection circuit, etc. in the switching power supply into one chip, which can form a high-efficiency isolated switching power supply without an industrial frequency transformer. The more representative ones are the TEA1520 series switching power supply developed by Philips of the Netherlands in 2000, the NCP1050 and NCP1000 series single-chip switching power supplies developed by Onsemi of the United States from 1998 to 2002, the MC33370 series five-terminal switching power supply launched by Motorola of the United States in 1999, and the first generation of TOPSwitch series products launched by PI of the United States in 1994, which were praised as "top switching power supplies", the TOPSwitch-Ⅱ series launched in 1997, the TinySwitch series launched in 1998, the TOPSwitch-FX series launched in 2000, and the TOPSwitch-GX series launched later, which were promoted as mainstream products. This article takes the TOP247Y in the TOPSwitch-GX series as an example to specifically explain its performance characteristics and typical design applications.
2. Features of the TOPSwitch-GX series of six-terminal switching power supply chips [2]
1 The TOPSwitch-GX is mainly composed of a control voltage source, a bandgap reference voltage source, a frequency jitter oscillator, a pulse width modulator, a shunt regulator/error comparator, a gate drive stage and an output stage, a high-voltage power switch tube (MOSFET), a bias circuit, an overcurrent protection circuit, an overvoltage, undervoltage detection and protection circuit, an overheating protection circuit, a power-on reset circuit, a soft start circuit, a circuit for automatically reducing the switching frequency when lightly loaded, a stop logic, and a voltage comparator with a start voltage of 1V. The output end is isolated from the power grid through a high-frequency transformer, making it small in size, high in efficiency, safe and reliable.
2 The input AC voltage range is very wide, which can be a fixed 230VAC±15%, or a wide range of 85-265VAC, but under the wide range input condition, the maximum input power is reduced by about 40%. The frequency range of the input signal is 47-440HZ.
[page] 3 The typical switching frequency is 132K. It can work in half-frequency mode when lightly loaded. The maximum duty cycle can reach 80%, and the power efficiency is about 80%, with a maximum of 90%.
4 TOPSwitch-GX has six pins, namely control terminal C, line detection terminal L, limit current setting terminal X, source terminal S, switching frequency selection terminal F, and drain terminal D. The control terminal C has multiple functions: (1) The voltage VC at this terminal provides bias for the on-chip parallel regulator and gate driver stage, (2) the duty cycle is adjusted by controlling the current at this terminal, and (3) as the connection point between the power branch and the automatic restart/compensation capacitor, the frequency of the automatic restart is determined by an external bypass capacitor, and the control loop is compensated.
5 TOPSwitch working principle The duty cycle is adjusted by the feedback current IC to achieve voltage regulation. For example, when the output voltage VO of the power supply decreases due to some reason, the optocoupler feedback circuit will make IC↓→D↑→VO↑, thereby achieving VO stability.
6 It can effectively reduce the electromagnetic interference (EMI) generated by the switching power supply.
7 The peripheral circuit is simple and low-cost. The external circuit only needs to be connected to the rectifier filter, high-frequency transformer, drain clamp protection circuit, feedback circuit and output circuit. This can increase circuit reliability and reduce costs.
III: Typical design [3]
The 24V/72W monolithic flyback switching power supply based on TOP247Y is shown in Figure 1.
Figure 1: 24V, 72W switching power supply
The input end is 110V AC, which passes through the electromagnetic interference filter (EMI) (C1, T1), and then passes through the voltage doubler rectifier circuit composed of D1/D2 and C2/C3 to the primary side of the high-frequency transformer. R1/R2 is a balancing resistor that can balance the voltage on C2/C3 to prevent a capacitor from being broken down due to excessive voltage drop. During the conduction period of TOP247Y, the lower end of the primary side of the high-frequency transformer is negative. From the same-name terminal, it can be seen that the secondary side stores energy at this time and does not output energy to the outside. When TOP247Y is off, the secondary side can output energy to the outside. Therefore, this circuit topology is a flyback topology. A protection circuit must be added to the primary side of the high-frequency transformer to absorb the high voltage generated by the leakage inductance. The SNUBBER circuit composed of the ultra-fast recovery diode D3, transient voltage suppressor VS (P6KE200) and RC in the figure can clamp the peak voltage to a safe value. The line detection terminal L realizes overvoltage/undervoltage protection; voltage feedforward (used to reduce the maximum duty cycle when the grid voltage is too low). After the secondary voltage is rectified and filtered by D4, C6, L1, and C8, a regulated output of +24V and 3A is obtained. In order to reduce the loss of the rectifier tube, D4 uses a MBR1060 10A/60V Schottky diode. C5 and R6 are connected in parallel at both ends of D4 to prevent D4 from self-oscillating (ringing) in the high-frequency switching state, and R11 is used as a dummy load under no-load conditions. Improve the load regulation rate under light load. Changing the ratio of the high-frequency transformer or the ratio of R8 and R9 can change the size of the output DC voltage. The external error amplifier is composed of an adjustable precision shunt regulator TL431, which forms an optocoupler feedback circuit with the linear optocoupler CNY17-2. The voltage regulation principle is that when the output voltage VO fluctuates, the sampled voltage obtained after the voltage division by R8 and R9 is compared with the 2.5V reference voltage in TL431 to generate an external error voltage △u, and then the optocoupler is used to make the IC produce corresponding changes, and the output duty cycle is adjusted to achieve the purpose of voltage regulation. After the feedback winding voltage is rectified and filtered by D5 and C7, a 12V feedback voltage is generated, which is passed through CNY17-2 to provide bias voltage to the control end of TOP247Y. C9 is a bypass capacitor, which forms a compensation circuit of the control loop with R10 and sets the automatic restart frequency.
[page] Four: Design points
Device selection:
1 First, select a suitable TOPSwitch tube according to the power requirements and efficiency requirements.
2 For the selection of diodes (D3, D4), ultra-fast recovery diodes should be selected. If the output voltage is low, D4 can use a Schottky tube with a low reverse withstand voltage to better improve the efficiency of the system.
3 Optocouplers with linear current transfer ratio (CTR) should be selected, such as CNY17-2, PC817A, NEC2501, 6N137, etc. It is not advisable to use ordinary optocouplers such as 4N25 and 4N35. The latter has poor linearity, which will cause distortion and affect the voltage regulation performance of the switching power supply.
High-frequency transformer design [4]
The quality of high-frequency transformer design is the key to the success of the entire system. You can first use the PI EXPERT software provided by PI to perform a preliminary design, and then modify the design on this basis. Unlike the transformer design in the forward circuit, the flyback transformer core must have a suitable air gap. According to the system frequency requirements (130K), select a high-frequency ferrite core. While meeting the power capacity, improve the winding method to minimize the primary leakage inductance. In this power supply design, the primary leakage inductance is less than 10UH. It meets the system requirements well.
V: Conclusion
The single-chip switching power supply is a new product with great prospects and influence. This article takes the typical chip TOP247Y in the current mainstream TOPSwitch-GX series as an example to give a specific design. It has universal significance for the design of single-chip switching power supplies.
References
[1] Sha Zhanyou. The latest application technology of single-chip switching power supply. Beijing: Machinery Industry Press, 2003,6
[2] Top242-250. Power integration, March 2004
[3] Liu Shengli. Practical technology of modern high-frequency switching power supply. Beijing: Electronic Industry Press, 2001,9
[4] Flyback Transformer Design for TOPSwitch Power Supplies. Power integration, June 1996
Keywords：TOPSwitch
Reference address：Development of flyback monolithic switching power supply based on TOP247Y
I: Overview of the development of monolithic switching power supplies [1]
In the mid- and late 1990s, with the development of integrated circuits, various types of monolithic switching power supply integrated circuits appeared. It integrates the pulse width controller, power output stage, protection circuit, etc. in the switching power supply into one chip, which can form a high-efficiency isolated switching power supply without an industrial frequency transformer. The more representative ones are the TEA1520 series switching power supply developed by Philips of the Netherlands in 2000, the NCP1050 and NCP1000 series single-chip switching power supplies developed by Onsemi of the United States from 1998 to 2002, the MC33370 series five-terminal switching power supply launched by Motorola of the United States in 1999, and the first generation of TOPSwitch series products launched by PI of the United States in 1994, which were praised as "top switching power supplies", the TOPSwitch-Ⅱ series launched in 1997, the TinySwitch series launched in 1998, the TOPSwitch-FX series launched in 2000, and the TOPSwitch-GX series launched later, which were promoted as mainstream products. This article takes the TOP247Y in the TOPSwitch-GX series as an example to specifically explain its performance characteristics and typical design applications.
2. Features of the TOPSwitch-GX series of six-terminal switching power supply chips [2]
1 The TOPSwitch-GX is mainly composed of a control voltage source, a bandgap reference voltage source, a frequency jitter oscillator, a pulse width modulator, a shunt regulator/error comparator, a gate drive stage and an output stage, a high-voltage power switch tube (MOSFET), a bias circuit, an overcurrent protection circuit, an overvoltage, undervoltage detection and protection circuit, an overheating protection circuit, a power-on reset circuit, a soft start circuit, a circuit for automatically reducing the switching frequency when lightly loaded, a stop logic, and a voltage comparator with a start voltage of 1V. The output end is isolated from the power grid through a high-frequency transformer, making it small in size, high in efficiency, safe and reliable.
2 The input AC voltage range is very wide, which can be a fixed 230VAC±15%, or a wide range of 85-265VAC, but under the wide range input condition, the maximum input power is reduced by about 40%. The frequency range of the input signal is 47-440HZ.
[page] 3 The typical switching frequency is 132K. It can work in half-frequency mode when lightly loaded. The maximum duty cycle can reach 80%, and the power efficiency is about 80%, with a maximum of 90%.
4 TOPSwitch-GX has six pins, namely control terminal C, line detection terminal L, limit current setting terminal X, source terminal S, switching frequency selection terminal F, and drain terminal D. The control terminal C has multiple functions: (1) The voltage VC at this terminal provides bias for the on-chip parallel regulator and gate driver stage, (2) the duty cycle is adjusted by controlling the current at this terminal, and (3) as the connection point between the power branch and the automatic restart/compensation capacitor, the frequency of the automatic restart is determined by an external bypass capacitor, and the control loop is compensated.
5 TOPSwitch working principle The duty cycle is adjusted by the feedback current IC to achieve voltage regulation. For example, when the output voltage VO of the power supply decreases due to some reason, the optocoupler feedback circuit will make IC↓→D↑→VO↑, thereby achieving VO stability.
6 It can effectively reduce the electromagnetic interference (EMI) generated by the switching power supply.
7 The peripheral circuit is simple and low-cost. The external circuit only needs to be connected to the rectifier filter, high-frequency transformer, drain clamp protection circuit, feedback circuit and output circuit. This can increase circuit reliability and reduce costs.
III: Typical design [3]
The 24V/72W monolithic flyback switching power supply based on TOP247Y is shown in Figure 1.
The input end is 110V AC, which passes through the electromagnetic interference filter (EMI) (C1, T1), and then passes through the voltage doubler rectifier circuit composed of D1/D2 and C2/C3 to the primary side of the high-frequency transformer. R1/R2 is a balancing resistor that can balance the voltage on C2/C3 to prevent a capacitor from being broken down due to excessive voltage drop. During the conduction period of TOP247Y, the lower end of the primary side of the high-frequency transformer is negative. From the same-name terminal, it can be seen that the secondary side stores energy at this time and does not output energy to the outside. When TOP247Y is off, the secondary side can output energy to the outside. Therefore, this circuit topology is a flyback topology. A protection circuit must be added to the primary side of the high-frequency transformer to absorb the high voltage generated by the leakage inductance. The SNUBBER circuit composed of the ultra-fast recovery diode D3, transient voltage suppressor VS (P6KE200) and RC in the figure can clamp the peak voltage to a safe value. The line detection terminal L realizes overvoltage/undervoltage protection; voltage feedforward (used to reduce the maximum duty cycle when the grid voltage is too low). After the secondary voltage is rectified and filtered by D4, C6, L1, and C8, a regulated output of +24V and 3A is obtained. In order to reduce the loss of the rectifier tube, D4 uses a MBR1060 10A/60V Schottky diode. C5 and R6 are connected in parallel at both ends of D4 to prevent D4 from self-oscillating (ringing) in the high-frequency switching state, and R11 is used as a dummy load under no-load conditions. Improve the load regulation rate under light load. Changing the ratio of the high-frequency transformer or the ratio of R8 and R9 can change the size of the output DC voltage. The external error amplifier is composed of an adjustable precision shunt regulator TL431, which forms an optocoupler feedback circuit with the linear optocoupler CNY17-2. The voltage regulation principle is that when the output voltage VO fluctuates, the sampled voltage obtained after the voltage division by R8 and R9 is compared with the 2.5V reference voltage in TL431 to generate an external error voltage △u, and then the optocoupler is used to make the IC produce corresponding changes, and the output duty cycle is adjusted to achieve the purpose of voltage regulation. After the feedback winding voltage is rectified and filtered by D5 and C7, a 12V feedback voltage is generated, which is passed through CNY17-2 to provide bias voltage to the control end of TOP247Y. C9 is a bypass capacitor, which forms a compensation circuit of the control loop with R10 and sets the automatic restart frequency.
[page] Four: Design points
Device selection:
1 First, select a suitable TOPSwitch tube according to the power requirements and efficiency requirements.
2 For the selection of diodes (D3, D4), ultra-fast recovery diodes should be selected. If the output voltage is low, D4 can use a Schottky tube with a low reverse withstand voltage to better improve the efficiency of the system.
3 Optocouplers with linear current transfer ratio (CTR) should be selected, such as CNY17-2, PC817A, NEC2501, 6N137, etc. It is not advisable to use ordinary optocouplers such as 4N25 and 4N35. The latter has poor linearity, which will cause distortion and affect the voltage regulation performance of the switching power supply.
High-frequency transformer design [4]
The quality of high-frequency transformer design is the key to the success of the entire system. You can first use the PI EXPERT software provided by PI to perform a preliminary design, and then modify the design on this basis. Unlike the transformer design in the forward circuit, the flyback transformer core must have a suitable air gap. According to the system frequency requirements (130K), select a high-frequency ferrite core. While meeting the power capacity, improve the winding method to minimize the primary leakage inductance. In this power supply design, the primary leakage inductance is less than 10UH. It meets the system requirements well.
V: Conclusion
The single-chip switching power supply is a new product with great prospects and influence. This article takes the typical chip TOP247Y in the current mainstream TOPSwitch-GX series as an example to give a specific design. It has universal significance for the design of single-chip switching power supplies.
References
[1] Sha Zhanyou. The latest application technology of single-chip switching power supply. Beijing: Machinery Industry Press, 2003,6
[2] Top242-250. Power integration, March 2004
[3] Liu Shengli. Practical technology of modern high-frequency switching power supply. Beijing: Electronic Industry Press, 2001,9
[4] Flyback Transformer Design for TOPSwitch Power Supplies. Power integration, June 1996
Previous article：Introduction to the hot exchange method used in outdoor DC switching power supplies
Next article：Switching power supply using TOP Switch design
Recommended ReadingLatest update time:2024-11-16 23:42
Multi-output switching power supply based on TOPSwitch-GX series
1 Introduction
Multi-channel output switching power supplies are widely used in various complex low-power electronic systems. As for multi-channel outputs, usually only one channel with low output voltage and large output current variation range is used as the main circuit for feedback adjustment control to ensure
[Power Management]
- Popular Resources
- Popular amplifiers
-
Design, production and debugging of flyback switching power supply (by Chen Yongzhen and Chen Zhibo) - Chip Manufacturing: A Practical Tutorial on Semiconductor Process Technology (Sixth Edition)
- TOPSwitch single-ended flyback design flow chart
- COM Express Module Base Specification_R3.0 (text can be copied, label can be added)
Design, production and debugging of flyback switching power supply (by Chen Yongzhen and Chen Zhibo)
Recommended Content
Latest Power Management Articles
- MathWorks and NXP Collaborate to Launch Model-Based Design Toolbox for Battery Management SystemsMathWorks and NXP collaborate to launch Model-Based Design Toolbox for Battery Management Systems, a new toolbox that simplifies the design, testing, and optimization of battery management systems on NXP processors. ...
- STMicroelectronics' advanced galvanically isolated gate driver STGAP3S provides flexible protection for IGBTs and SiC MOSFETsPower control for industrial motor drives such as air conditioners, home appliances and factory automation, and energy applications such as charging stations, energy storage systems, and power supplies November 13, 2024, China - STMicroelectronics ...
- New diaphragm-free solid-state lithium battery technology is launched: the distance between the positive and negative electrodes is less than 0.000001 metersOn November 13, Tailan New Energy and Changan Automobile jointly announced a major technological breakthrough - the release of diaphragm-free solid-state lithium battery technology. Tailan achieved diaphragm-free solid-state lithium battery technology through disruptive innovation. ...
- [“Source” Observe the Autumn Series] Application and testing of the next generation of semiconductor gallium oxide device photodetectorsGallium oxide (Ga2O3) detector is a photodetector based on ultra-wide bandgap semiconductor materials, mainly used for the detection of solar-blind ultraviolet light. Its unique physical and chemical properties make it widely used in many application fields. ...
- 采用自主设计封装，绝缘电阻显著提高！ROHM开发出更高电压xEV系统的SiC肖特基势垒二极管采用自主设计封装，绝缘电阻显著提高！ROHM开发出支持更高电压xEV系统的SiC肖特基势垒二极管~与普通产品相比，可确保约1 3倍的爬电距离。即 ...
- Will GaN replace SiC? PI's disruptive 1700V InnoMux2 is here to demonstrate
- From Isolation to the Third and a Half Generation: Understanding Naxinwei's Gate Driver IC in One Article
- The appeal of 48 V technology: importance, benefits and key factors in system-level applications
- Important breakthrough in recycling of used lithium-ion batteries
MoreSelected Circuit Diagrams
MorePopular Articles
- Innolux's intelligent steer-by-wire solution makes cars smarter and safer
- 8051 MCU - Parity Check
- How to efficiently balance the sensitivity of tactile sensing interfaces
- What should I do if the servo motor shakes? What causes the servo motor to shake quickly?
- 【Brushless Motor】Analysis of three-phase BLDC motor and sharing of two popular development boards
- Midea Industrial Technology's subsidiaries Clou Electronics and Hekang New Energy jointly appeared at the Munich Battery Energy Storage Exhibition and Solar Energy Exhibition
- Guoxin Sichen | Application of ferroelectric memory PB85RS2MC in power battery management, with a capacity of 2M
- Analysis of common faults of frequency converter
- In a head-on competition with Qualcomm, what kind of cockpit products has Intel come up with?
- Dalian Rongke's all-vanadium liquid flow battery energy storage equipment industrialization project has entered the sprint stage before production
MoreDaily News
- Allegro MicroSystems Introduces Advanced Magnetic and Inductive Position Sensing Solutions at Electronica 2024
- Car key in the left hand, liveness detection radar in the right hand, UWB is imperative for cars!
- After a decade of rapid development, domestic CIS has entered the market
- Aegis Dagger Battery + Thor EM-i Super Hybrid, Geely New Energy has thrown out two "king bombs"
- A brief discussion on functional safety - fault, error, and failure
- In the smart car 2.0 cycle, these core industry chains are facing major opportunities!
- The United States and Japan are developing new batteries. CATL faces challenges? How should China's new energy battery industry respond?
- Murata launches high-precision 6-axis inertial sensor for automobiles
- Ford patents pre-charge alarm to help save costs and respond to emergencies
- New real-time microcontroller system from Texas Instruments enables smarter processing in automotive and industrial applications
Guess you like
- 3 hours of practice + analysis (live): TI engineers will guide you to get started with MSP430. Make an appointment now for free~
- Welding problem or SI problem? You decide!
- Issues that should be paid attention to when using CMOS circuits
- Is Python worth learning? Is it easy to learn?
- TMP112 read timing is incorrect, can produce results, 9 more clocks
- High salary recruitment of hardware maintenance engineers
- Audio Power Amplifier Design Handbook (6th Edition)
- Power supply voltage drop problem
- This circuit is for audio amplification. Please explain it to me.
- Modification of 4-20mA two-wire passive digital display meter Part 10 (Small task completed)
京公网安备 11010802033920号