Switching power supply and TV

Abstract

The invention discloses a switching power supply and a television set, wherein the switching power supply comprises a constant current switching circuit, a first single-stage PFC circuit, a first transformer, a constant current feedback circuit, a constant voltage switching circuit, a second single-stage PFC circuit, and The second transformer; the constant current feedback circuit samples the current output by the first transformer, and feeds back the sampled current to the first single-stage PFC circuit; the first single-stage PFC circuit outputs a switch signal according to the sampled current to drive a constant current switch The circuit is turned on or off, and the load current is controlled to be constant; the second single-stage PFC circuit outputs a switch signal to drive the constant voltage switch circuit to be turned on or off; the second single-stage PFC circuit samples the output voltage of the second transformer to obtain The voltage is sampled, and according to the sampled voltage, the duty cycle of the switch signal is adjusted to adjust the voltage output to the main board, and the voltage of the main board is controlled to be constant. The technical scheme of the invention improves power conversion efficiency, stability and reduces costs.

Description

technical field [0001] The invention relates to the technical field of power supplies, in particular to a switching power supply and a television using the switching power supply. Background technique [0002] When the load power demand is greater than 75W, because the national standard requires the power factor to be greater than 0.9, the traditional TV power supply architecture is as follows: figure 1 As shown, the power supply needs to perform power factor correction first, and then perform DC-DC conversion, so that the 24V output by the constant voltage output power supply needs to be boosted by BOOST to supply power to the backlight strip, which will make the power conversion efficiency low and increase The cost of the constant current board and the cost of the PFC circuit are reduced. At the same time, this power structure alternately outputs constant current and constant voltage, making dynamic loads of constant voltage and constant current susceptible to interferenc...

AI Technical Summary

Problems solved by technology

[0002] When the load power demand is greater than 75W, because the national standard requires the power factor to be greater than 0.9, the traditional TV power supply architecture is as follows: figure 1 As shown, the power supply needs to perform power factor correction first, and then perform DC-DC conversion, so that the 24V output by the constant voltage output power supply needs to be boosted by BOOST to supply power to the backlight strip, which will make the power conversion efficiency low and increase The cost of the constant current board and the cost of the PFC circuit

At the same time, this power structure alternately outputs constant current and constant voltage, making dynamic loads of constant voltage and constant current susceptible to interference

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