OZ960 is a high-voltage inverter control circuit for liquid crystal color display backlight produced by the convex and concave company. The backlight high-voltage inverter power circuit composed of OZ960 can convert the input unsteady DC voltage into a high voltage of approximately sine wave to drive the backlight tube. The figure below shows the actual application circuit of OZ960. This kind of circuit has been applied in LCD high voltage high voltage board. (1) Drive Control Circuit The drive control circuit consists of U901 (OZ960) and its peripheral components. (2) Full-bridge drive circuit The full-bridge drive circuit is used to generate AC high voltage that meets the requirements and drive CCFL operation. The driving circuit is composed of Q904, Q905, Q906, Q907, T901 and the like. This is a full-bridge circuit structure with zero voltage switching. Vcc (typically 12V) voltage is applied to the sources of Q904 and Q906, the source of Q905 and Q907 is grounded, and the drive pulse is output at OZ960 (the waveform is shown in Figure 5). 17)) Under control, Q904 and Q907 are turned on at the same time, Q905 and Q906 are turned on at the same time, and when Q904 and Q907 are turned on, Q905 and Q906 are turned off, that is, Q904, Q907 and Q905, Q906 are alternately turned on. The output of the symmetrical switch tube drive pulse, through the resonant tank circuit composed of C915, C916, C917, C918, step-up transformer T901 and backlight tube, generates a voltage and current similar to a sine wave, and illuminates the backlight tube. (3) Brightness adjustment circuit (4) Protection circuit - soft start protection circuit More about the device OZ960 information: integrated circuit query network http://
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The OZ960 has the following features: high efficiency, zero voltage switching, wide input voltage range, constant operating frequency, wide dimming range, soft start function, built-in turn-on protection and overvoltage protection. The internal circuit block diagram of OZ960 is shown in the figure on the right. The pin functions are shown in the following table. 
The Vdd voltage generated by the switching power supply (typically 5V) is limited by R904 and is applied to the 5th pin of the OZ960 power supply terminal to provide the OZ960 with the voltage required for operation.
When the LCD color TV needs to be lit, the ON/OFF signal output from the microcontroller is high. After R903, the voltage of the 3 pin applied to the OZ960 is high (the voltage greater than 1.5V is high).
OZ960 is powered at 5 feet, and after the 3 feet get a high level signal, the internal oscillation circuit starts to work. The oscillation frequency is determined by the size of the 6-pin, 10-pin external timing resistor R908 and timing capacitor C912. After the oscillation circuit works, an oscillation pulse is generated, which is applied to the internal zero-voltage switching phase shift control circuit and the driving circuit. After the transformation and shaping, the PWM pulses are output from the (19), (20), (12), and (11) pins, and the whole is Bridge drive circuit.
The (14) pin of OZ960 is the brightness control terminal. When the brightness needs to be adjusted, the brightness control voltage ADJ generated by the microcontroller is divided by R906 and R907, and added to the (14) pin of OZ960. After being processed by the internal circuit, the pass is passed. Controls the duty cycle of the drive pulse output from the OZ960 to achieve brightness control.
The 4-pin soft start end of the OZ960 is connected to the soft start capacitor C904, which functions as a soft start timing. After the OZ960 is working, the 4-pin internal circuit charges the 4-pin external soft-start timing capacitor C904. As the voltage across the C904 increases, the drive pulse of the OZ960 output controls the energy supplied by the drive tube to the high-voltage transformer. The use of a soft-start circuit prevents excessive inrush current during initial operation of the backlight.
——Overvoltage protection circuit
The overvoltage protection circuit in the OZ960 prevents the high voltage transformer secondary of the lamp from generating excessive voltage under abnormal conditions and damaging the high voltage transformer and the lamp. In the circuit, the high voltage generated by the secondary of T901 is divided by R930, R932 and R931, R933, and is used as the sampling voltage, and is added to the 2 feet of OZ960 via D909 and D910. In the startup phase, the 2-pin of the OZ960 detects the secondary voltage of the high-voltage transformer. When the 2-pin voltage reaches 2V, the 0Z960 will no longer raise the output voltage and enter the stable output voltage phase.
——Overcurrent protection circuit The overcurrent protection circuit is used to protect the CCFL from aging or damage due to excessive current. In the circuit, R936 and R937 are overcurrent detection resistors. The voltage across R936 and R937 changes with the working current. The higher the current, the higher the voltage across R936 and R937. This voltage is added to the 9 feet of OZ960 via D912 and D914. As the current detecting terminal, the lamp current is stabilized by the internal control circuit. If the operating current of the CCFL is too large, the voltage of the 9-pin of the OZ960 will rise a lot. When a certain value is reached, the OZ960 stops processing the output drive pulse through the internal processing of the OZ960 to achieve the purpose of protection.