Power adapter


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Power adapter

A power adapter, also known as an AC/DC power converter, converts 220V AC to the required DC voltage. The adapters currently on the market all have power transformers and rectifying filters inside. Output power varies from a few tenths of a watt to a few watts, with several voltages available. However, it is large in volume and no voltage stabilizing circuit is used, so the power supply quality and efficiency are not high. If TinySwitch series is selected, the bulky power transformer can be removed, and it has the advantages of high efficiency, small size, good voltage stabilizing performance and low cost, which can completely replace the traditional plug power adapter.
A, 220V plug AC/DC power adapter
Use TNY253P design into 9V, 0. The 5W plug AC/DC power adapter circuit is shown in figure 5-10-l. In order to simplify the circuit and reduce the cost, the energy terminal (EN) will now be suspended, TNY253P working in skip cycle mode (i.e. discontinuous on/off), output constant power. Uo is set by VDZ. When the EN terminal is suspended, VDZ can withstand the maximum power. Here, choose 2CWl of 1.5w and 9.1v. Model 06 domestic pressure regulator. VDl is a half - wave rectifying diode.
It is composed of TNY254P +9V, 170mA(1. SW) AC/DC power adapter circuit is shown in figure 5-10-2. The circuit USES two IC: TNY254P four terminal single chip power adapter (1C1), LTV817 optical coupler (1C2). 85 -- 265V alternating current through VDI -- VD4, C true, C rectification filter, the generation of dc high voltage. RF is a fuse resistor, which can be replaced by a fuse tube. Electromagnetic interference filter by C, brother, ruler; And C2, where 200g resistance is used instead of filter inductance to reduce the circuit cost. Ruler d and C can absorb peak voltage on drain electrode and reduce electromagnetic interference. G is the bypass capacitance. Secondary winding voltage through VD5, G, L2 and (:? Rectified filter, output +9V voltage. The optical coupler LTV817 and the regulator 1N5237C are used to detect the output voltage and feed back to TNY254P. The output voltage is set by the forward voltage drop of LED in the optical coupler and the stable voltage of VDZ.
Finally, some points need to be explained: (1) design high-frequency transformer should make TNY254P work in discontinuous mode; (2) "the capacity of not more than 68pF; (3) in order to further improve the accuracy of the output voltage, a resistor of several hundred euros to 1,000 euros can be connected in parallel at both ends of the LED of IC2 to provide the VDZ with a bias current of 1-5ma; (4) to improve the power efficiency, can be 5mil inductance and 4. Replace R1 with 7kfl resistor in parallel.
Laptop power adapter
A sealed 70W notebook power adapter module composed of TOP249Y is described below.
1. Performance characteristics and technical indicators
(1) the ac input voltage range of the adapter is 85-265v, the output voltage is 19V, and the maximum output current is 3. 68 a. When the ambient temperature is 50℃, the maximum output power can be up to 70W, which can be used as an AC/DC power converter for notebook computers.
(2) high efficiency. Even under adverse conditions of ac input voltage of 85V and ambient temperature of 50℃, the power supply efficiency can reach 84%. When the ac input voltage is 115V, the no-load power consumption is lower than 370mW.

| release time：2019.09.24 Source：

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Power adapter