The OZ8022 is a non-isolated, high-efficiency, precision constant-current driver chip from O 2 Micro, which uses the buck architecture. The most exciting part of it is the three-stage dimming function realized by the wall switch. With this feature, users can use lighting products that adjust the brightness of their light source without any changes to the home. Below we will introduce some features of the OZ8022 chip: Valley switching technology achieves high efficiency The OZ8022 uses a valley detection technology internally, and the near-zero current turn-on effectively improves the conversion efficiency (Figure 1a). Gate is the output waveform of OZ8022, Vds is the voltage across MOS DS, and IL is the current waveform of the output inductor. From the figure we can see that when the Gate state is "on", the voltage drop across Vds is small, low, and the output inductor current begins to increase; when the Gate state is "off", the output inductor begins to discharge. When the inductor discharge is completed, the Vds of the MOS appears at the bottom. At this time, the OZ8022 ZCD pin detects the Vds valley Gate through the auxiliary winding and turns on again, and the switching loss is minimal at this time. Through experiments, it is assumed that a 5 to 8W LED driver can achieve more than 90% efficiency. High precision constant current In the conventional Buck line, the current is detected as shown in Figure 1b. When Gate is "on", a current I2 is formed. I2 flows through R1 and forms a voltage across R1, which is controlled by Sense to make it constant output. However, when Gate is "off", L1 reverses and forms a discharge loop I1 with the LED through the freewheeling diode D1. However, this discharged current IC cannot be detected, and the magnitude of the I1 energy is determined by the inductance of L1. Therefore, the constant current accuracy of this conventional Buck line is not ideal. Based on the insufficiency of the traditional Buck line, O2Micro introduced the OZ8022 control chip. As shown in Fig. 1c, when the Q1 conduction current forms a current loop I1 through R1, L1 and the LED, the OZ8022 detects the current I1 flowing through R1 and the LED through the sense pin and controls it. When Q1 is turned off, L1 is reversed, energy is again formed into current loop I2 through LED and freewheeling diode D1, and this current can also control the magnitude of I2 from the voltage drop formed across R1. Therefore, in this way, regardless of whether Q1 is turned on or off, the current at the LED terminal can be accurately detected, thereby achieving high-precision constant current control. This control method has been patented by O2Micro.
16V AC DC wall mount switching power adapter was widely
used for any small power device, such as CCTV Cameras, wireless routers, LED
strip, ADSL cats, HUB, switches, security cameras, audio/video power supply.
For 16V wall mount power supply, the maximum output current is 2.25A,total 36W
output. Our power adaptor meets different certificates for different countries`
request – like UL list/CCC-CQC/ PES/SAA/C-TICK/CB/GB certificate. All our
switching power supplies were getting 2-hours burn-in test & 3KV high
voltage test during production.
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