OZ9976是一款CCFL控制集成电路,应用广泛,应用电路复杂,且故障率较高.为了让广大电子技术工作者理解该电路,并能对电路故障作出准确的分析和检修,本文从OZ9976的框图及特点出发,对OZ9976的应用电路进行了全面剖析,在此基础上再对电路的故障作了深入的探究.实践表明,本文内容准确、实用,对指导大家理解电路和检修故障具有积极的作用.

In order to improve the reliability of the switching power supply,reduce failure rate,improve circuit performance,enhance the output power of the power supply,proposed a half bridge resonant switching power supply design based on the L6799.Using L6799 as the PFM pulse generator,with half bridge driver circuit and LC resonant circuit can constitute PFM switching power supply with high performance,Practice shows that this power supply in the premise of + 18V output,the Maximum output current of 4.5A above,the maximum output power of 80W above,voltage regulator range up to 150 ～270V.The power supply can be used in digital office equipment and LED lighting equipment.

为了简化卫星数字电视接收机的电路,降低接收机的成本,同时又能满足收视要求,提出了单芯片电路设计方案.使用超大规模多功能芯片MB87L3356为核心,辅以调谐解调器、视频编码器、音频DAC等少量外围元器件,就能构成廉价型卫星数字电视接收系统.实践表明,该系统能接收950~2150MHz范围内的全部免费频道,同时具有较好的画质和音质.且软件升级方便,是一款极具应用前景的电路.

为了减小功耗,提高效率,实现电路的集成化、小巧化和贴片化,提出了一种全数字功率放大器设计方案.采用RT9107为功率芯片,再配置优质的二阶低通滤波器,就能构成高性能的双声道全数字功率放大器.该功放器采用I2S总线输入,PWM信号输出方式,不但具有元件少,体积小的特点,而且还实现了音频信号的全数字处理.实践表明,此功率放大器的最大输出功率可达2x18W,总谐波失真度加噪声(THD+ N)在3％以下,电路效率可达90％以上,频率响应可达20 Hz～ 20 kHz.

为了减小能耗,提高效率,实现电路贴片化,同时又能获得比较理想的音质,提出了一种D类功率放大器设计方案.以STA335BW为主芯片,配以优质的二阶低通滤波器,就能构成高性能的D类功率放大器.实践表明,此功率放大器的输出功率可达2× 16 W,总谐波失真度(THD)在1％以下,电路效率可达90％,频响范围可达20 Hz～20 kHz.该放大器可用于数字声像设备中,具有广阔的应用前景.

The TEA1521P is a new type of power controller,is widely used.The paper starts with the characteristics and structure of TEA1521P,It makes a comprehensive introduction to the switching power based on TEA1521P,in-depth analysis of these switching power works.On this basis,further detailed analysis of the characteristics of this type of switching power failure and repair methods.In this paper, the majority of electronic enthusiasts, the electronic product maintenance personnel and electronic technology professional teachers and students to help.

In order to improve the efficiency,reduce energy consumption,as well as simplify the circuit and save cost,it proposed the scheme of PF7900 constant current LED backlight driving. It drives the LED backlight with PF7900 chip and a small amount of peripheral components constitute DC/DC booster circuit. And it is to use discrete component constitutes a constant current circuit to control the brightness of LED backlight,It can be achieved on LED constant current driver. The circuit has a great improvement in the aspect of energy saving and stability compared with the traditional LED drive circuit..The experiments show that the output voltage of driving circuit is very stable,load capability is strong and the brightness adjustment is convenient,It is a highly promising circuit.

Firstly,the digital TV encoding and decoding are briefly introduced.Then,the STi5518 functions,structure and characteristic are introduced.The structure and working process of single chip digital TV receiving system based on the STi5518 are mainly analyzed,including the STi5518's signal-source decoding process and external subsystem operating process.

TDA16846 is a new power controller which is widely used.Starting from the functions and features of TDA16846,the paper makes a comprehensive introduction of the application circuits of TDA 16846 in switching power supply, and a detailed analysis of the switching power supply based on TDA 16846.Furthermore,the paper deeply explore the fault types and repair skills of the switching power supply based on TDA16846.The content of the whole paper is accurate true and reliable.This paper is very helpful to the majority of electronics lovers,professional maintenance staffs,teachers and students in the field of electronic technology.

In order to obtain high-quality flat-panel image display,simplify the circuit and save cost,the NT68665 signal processing scheme is proposed.The NT68665 is a new type of flat panel image signal processor,which can be constituted of LCD signal processing system.Starting from the block diagram of the NT68665 function,the hardware environment and software functions are introduced,On this basis,the NT68665 application model is proposed,then the structure and working process of NT68665 signal processing system are analyzed.Experiment shows that the NT68665-based signal processing system has simple circuit and low cost,whose resolution rate is above 1 440×900/75 Hz.

In order to reduce energy consumption,simplify the circuit and save cost,a scheme of LD7552B switching power is proposed.The LD7552B is a green power chip,which has a great improvement at the start-up,regulator,protection and energy saving compared with the traditional power.An energy-saving switching power can be constituted matching the LD7552B with switch MOSFET,precision three-terminal regulator and switch transformer components.Experimental results show that the LD7552B switching power has a stable work in 90～240V communication environment,whose circuit efficiency can reach 90%,and can change the work mode automatically according to size of the load(in normal mode and green mode between transform).The switching power based on the LD7552B is a high-performance switching power supply.