Author: Ye Yunyan
1 Introduction
Power management solutions for lighting, such as inductive fluorescent lamps, electronic fluorescent lamps, compact fluorescent lamps (CFL), halogen control ICs, and high-pressure gas discharge lamps (H1D) technology for a wide range of applications In residential areas, businesses and cars, the electricity they need has been reduced, and a huge step forward in energy conservation. The adaptive control technology and high-voltage semiconductor junction isolation technology in the control integrated circuit are part of it and have been widely used. This will discuss the technology and application of new energy-saving lighting control ICs.
To understand this, first understand the main application areas of lighting control ICs.
It should be said that the main application areas of current lighting control ICs are: industrial building and office straight tube and compact fluorescent lighting; compact fluorescent lighting CFL and cold cathode fluorescent CCFL for residential and hotel; retail lighting equipment HID of halogen lamps and outdoor lighting equipment in the market; single white LED and camera xenon lamps; OLED and TFT displays, etc.
2. Characteristics of new lighting control IC technology
At present, there are two different typical methods in the design of lighting control ICs, ie electronic converters. The first method is based on an IC device, together with several external passive components, driving two high voltage (typically higher than 400V) power MOS transistors to implement a half bridge converter; the second method is based on two high voltage bipolar transistors and A large number of passive components, but only partial functions. Bipolar solutions are used in low- to mid-end applications where cost is extremely low.
2.1 High voltage isolation junction IC technology suitable for electronic ballasts
The key to energy-efficient product applications is cost and reliability, and these control ICs drive high-voltage isolation junction technology to meet these two requirements. Nowadays, the control IC-high voltage isolation junction technology has been widely applied to ballasts to produce competitive, high performance and highly reliable products. The key to energy-efficient product applications is cost and reliability, and these ICs drive high-voltage isolation junction technology to meet these two requirements. The challenge now is to extend them to other lighting market segments by designing new ICs that control the light source.
2.11 Features of High-Voltage Isolation Junction IC Technology This high-voltage isolation junction IC technology allows the circuit to be placed in an isolated "well" that can be isolated from the low-voltage circuit by 600V, as shown by the thick yellow line in Figure 1. This is because many of today's lighting technologies are associated with high-voltage power MOSFET technology, and the separation product line includes a large number of different types of devices, ranging from bridge rectifiers and Schottky diodes to power MOSFETs and IGBTs. With the addition of high-voltage isolation IC technology, it has opened the door to the infinite design of the power electronics industry.
High-voltage isolation junction IC technology is characterized by combining high-end and low-side drive functions into a single chip to control the topology of multiple switching converters. One of these topologies is a half bridge structure that is widely used in electronic ballasts. This makes the technology very suitable for the electronic ballast industry.
2.12 IR2153 and IR2166 Control ICs for Fluorescent Lighting
*IC IR2153 combines standard 555 timebase circuitry with high-end and low-side half-bridge drivers. Together with high-voltage MOSFETs, this IC was quickly adopted by lighting technology and became a standard controller for electronic ballasts that could serve as the basis for future development of lighting control ICs. Since the IR2153 is widely used and improved to become the IRS2153D, its top is more rugged and integrated with the necessary bootstrap diodes.
* The IR2156 and IR2166 control ICs are improved ballast technology based on the IR2153. It integrates additional functions into the IR2153, which is a more complete requirement for controlling fluorescent lamps. They include preheating and fault protection necessary to maximize lamp life and improve ballast reliability. The IR2166 is further enhanced with integrated Active Power Factor Correction (PFC) control, which together with ballast control enables a single-chip solution for the entire ballast. Because PFC is mandatory in Europe for power levels above 25W, the rest of the world is following the same trend.
The IR2166 includes two separate oscillators in the same IC, one for controlling the ballast input and the other for controlling the lamp. Also, to meet the new requirements of the T5 fluorescent lamp, the IR2166 has an end of life (EOL) pin to detect the overvoltage that occurs when the lamp is nearing the end of its life, safely shutting down the ballast before these high voltages cause damage.
The challenge now is to extend them to other lighting market segments by designing new ICs that control the light source.
2.2 Intelligent power technology fluorescent lamp drive circuit technology
It is a solution for driving linear fluorescent tubes with a fixed frequency (up to about 200KHz) half-bridge topology. The solution uses a system-on-a-chip approach: integrating the control section, protection circuitry, and power stage on the same chip VK06T. Due to this monolithic approach, system reliability has been improved, and system integration and small packages have been implemented to be smaller.
2.21 technical characteristics
The VK06TL driver circuit chip uses the intelligent power VIPovver M3-3 manufacturing technology, allowing the control part and power stage to be integrated on the same chip VK06TL. The power stage is an "emitter switch" made by placing a bipolar high voltage Darlington transistor and a low voltage MOS field effect transistor in a cascode configuration. Therefore, this scheme achieves a balance between the low-dropout of the bipolar device and the high breakdown voltage at the off state, and the switching speed of the MOS field effect transistor. Therefore, this "emitter switch" structure can achieve a very high frequency (around 200KHz).
2.22 VK06TL chip applied to fluorescent lamp ballast driver
Figure 2 is a diagram of a half-bridge converter design scheme for a fluorescent lamp discreeter using the VK06TL driver circuit.
In the half bridge converter of Figure 2, the VK06TL is designated for the upper and lower arms. Because of the two VK06TLs, almost no external components are required, and only one secondary winding can be used to turn on the primary side choke. Therefore, the fluorescent lamp-specific driver-half bridge converter is an extremely efficient and extremely low cost fluorescent lamp converter.
This converter is able to properly manage all the necessary operating conditions for a high-end fluorescent lamp application, namely start-up, preheat frequency and duration control, ignition and steady-state phases. This half-bridge enables overcurrent protection (EOL: lamp end of life), rectification effect protection and overtemperature protection to create a fully protected system.
The control and power stages of the chip are powered by the Vcc pin, which is connected to the DC bus through a resistor-capacitor (RC) network. During the startup phase, the capacitor is charged through a high-resistance resistor, so it only takes a few hundred microamps. Since the power bipolar crystal storage base current is recovered on the capacitor connected to the Vcc pin through the "Vcc charging network", the device supplies itself to itself during the working phase. This special feature of the VK06TL allows the use of lower power resistors, and the power supply to the bridge arm does not require a charge pump. This device must also be triggered from the SEC pin connected to the secondary winding.
It should be noted that this single-chip method achieves power stage current sensing without the need for external resistors and connectors. In addition, as described above, a single temperature-protection circuit can be integrated with a single device.
3. IC IR2520D for compact fluorescent lamp (CFL) CFL and TPS68000 for CCFL
3.1 IC IR2520D Features and Applications
* Presentation of IR2520D
Another major component of lighting control ICs includes compact fluorescent lamps (CFLs) and CCFLs. The traditional circuit that controls this lamp is self-oscillating and very cost sensitive. Due to reliability issues, the self-oscillating scheme actually hinders rapid development.
Because HVJI technology is mainly used to isolate high voltage circuits and level shift gate drive signal circuits. With the IR2520D, the HVJI function is extended to implement the necessary detection functions. Previous ICs required a separate pin for some kind of detection, such as DC bus undervoltage, overcurrent, filament open or lamp removed. The IR2520D uses HVJI technology and a new control algorithm to detect all required parameters on a single pin. However, this pin is the half-bridge midpoint that is often exchanged between the COM terminal and the high-voltage DC bus, which means that the detection must be done when the low-side half-bridge switch is turned on, and when the half-bridge high-side switch is turned on. The circuit must be able to withstand high voltages, and the IR2520D uses a third internal high voltage MOSFET to achieve this function. The IR2520D then uses the new control algorithms such as “Non-Zero Voltage Switching (ZVS) Protection†and “Crest Detection†to implement the necessary ballast functions. The other control pins are used to set the minimum operating frequency and warm-up time. Finally, coupled with the frequency vibration function, it typically shifts the frequency above a few kilohertz and back down to the minimum frequency to reduce the need for external EMI filtering. Integrating all of these features in a simple 8-pin package, the IR2520D is designed to be used in CFL products. This new solution will reduce the size and cost of CFL ballasts, increase manufacturing capabilities, and increase reliability to help with the adoption of CFL products and the further development of this market share. See Figure 3 for a schematic diagram of the IR2520D applied to the CFL.
*IR2520D integrated circuit main features:
Intelligent half-bridge driver, automatic reset short-circuit protection, automatic reset overload protection, latch over-temperature protection, frequency swing (with better EMl), micro-power start (150uA), phase adjustment for leading/back edge Light, output voltage drift comparison (longer lamp life), true soft start (to prevent overdrive), adaptive dead time, small 8-pin DIP/SOIC package. Its system includes: internal oscillator, advanced overload and short circuit protection, output voltage load compensation, dimming with external phase dimmer, longer lamp life, superior product reliability, and reduced component count.
3.2CCFL backlight controller
3.21 technical basis
The input voltage-backlight power supply is usually provided by a battery or a voltage regulator. For backlight power supplies, it is important to understand the available input voltage in order to select the best IC and power conversion topology to generate the output power required for the illumination.
Lighting Characteristics (Output Power) - A typical CCFL lamp requires 250VAC to 1000VAC (2 to 10mA) to support operation. The relationship between input voltage and output voltage indicates the best JC and power supply topology.
Power Topology - This section controls the transformer in different ways. Sometimes the input/output relationship indicates a certain topology. Different topological mechanisms correspond to different power conversion efficiencies.
Transformer type - Piezo (PieZO) can achieve smaller size and higher efficiency in some applications.
Control options - single or dual lamp control, brightness control.
3.22 Technical features: full power control for CCFL; magnetic or piezoelectric transformer control; 0penlamp protection and transformer protection; pulse brightness adjustment control for efficient and wider brightness adjustment range; four different Power topology, including half bridge
3.23 CCFL (Cold Cathode Fluorescent Lamp Backlight) TPS68000 High Efficiency Phase Shift Full Bridge CCFL Controller and Application
Main features: Input voltage range: 8V to 30V; integrated gate-driven full-bridge technology for 4-NMOS conversion.
Synchronous constant operating frequency; programmable phase delay for controlling the operating frequency of the slave operation; optical-voltage regulation and light-current stabilization; analog dimming and pulse dimming; adjustable split-mode dimming under multiple control devices Programmable correction voltage duration in startup or error state; turn-on protection and short-circuit protection; built-in high temperature protection and low voltage lockout mode; package mode: 30-pin TSSOP package. TPS68000 high efficiency phase-shift full-bridge CCFL controller guide The lamp application diagram is shown in Figure 4.
It can be applied to CCFL backlight power supply for desktop monitors and LCD TVs, and CCFL backlight power supply for notebook computers.
4, the world's first halogen converter IC
Part of the halogen lamp in the market is facing the challenge that this market is largely faced with reliability and performance issues. Electronic transformers are often damaged due to overload and short circuit faults. However, with the right technology, a halogen-to-converter IC can be the solution, that is, a three-terminal triac can be used to achieve a smooth and continuous dimming of the halogen tube.
The challenge for the IR2161 is to offer a wide range of protection features, lamp voltage regulation and dimming in a small 8-pin package (see Figure 5a), HVJI technology again, and new detection techniques. The IR2161 also uses a third internal high-voltage MOSFET to detect the half-bridge voltage. By detecting this voltage as it reaches zero during the dead time of each switching cycle, the IC can be continuously guaranteed once the half-bridge voltage is turned to the corresponding line. The rail voltage, each half bridge switch is turned on. By adopting this adaptive dead time function, it is possible to avoid hard switching and reduce switching loss. The IR2161 also includes a single current sense pin that is used to perform the necessary lamp voltage regulation, overload protection, and short-circuit protection (see Figure 5b).
The resulting IR2161 halogen lamp solution is a simple, superior design that reduces the total component count and provides higher performance. The IC+MOSFET combination solution will greatly enhance the manufacturing capabilities and reliability of these products. It also contributes to the further development of this market share.
5, the conclusion
It can be seen that with the development of new lighting technology or prior art, such as fluorescent tubes with very small diameters and even LEDs, they will create their own new market areas together with their related applications. The result is to further promote electronics. Energy efficient lighting products benefit the entire market.
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