A dc-dc converter with peak delay start notification

Abstract

The invention discloses a DC-DC converter with peak delay start notification, including a logic circuit, a PWM circuit, a FET circuit, a switcher, a peak comparator, a counter and a latch, a power supply VIN is connected to the switcher, and the PWM circuit outputs The signals are respectively connected to the input terminals of the counter and the switcher. The two output terminals of the switchable output of the switcher are respectively connected to the two input ports of the peak comparator through a peak hold circuit, and the output terminal of the counter is connected to the power supply of the peak comparator. terminal, the counter drives the peak comparator to output the comparison result to the enable terminal of the latch when the counting cycle is reached, the output terminal of the logic circuit is connected to the data terminal of the latch, and the output signal of the latch comprehensive logic circuit and the peak comparator The output result of the latch controls the output potential level of the latch, the output terminal of the latch is connected to the base of the triode, the emitter of the triode is grounded, and the collector of the triode is connected to the PGOOD pin. The invention enables the DC / DC converters to start up sequentially and avoids stacking of peak currents.

Description

technical field [0001] The invention relates to the technical field of circuit electronics, in particular to a DC-DC converter with peak delay start notification. Background technique [0002] Such as figure 1 As shown, a complete display system in the prior art usually consists of multiple unit display boxes. There is a power supply inside each independent display box, and the output voltage of different power supplies according to the design is between 4V~5.2V. In the prior art, 4.2V~5V / 200W~300W power supplies are widely used. Due to the low-voltage and high-current output characteristics, it can be seen that the heat generated by the secondary side is high, there are fewer suppliers, and the price is relatively expensive. Poor stability, low efficiency and other shortcomings. And in practical applications, since the LED display is mostly turned on 24 / 7 for a long time, the output of the power supply will often decline after long-term and high-temperature applications,...

AI Technical Summary

Problems solved by technology

[0005] Assuming that there are a considerable number of DC / DC converters in an LED display, if all the DC / DC converters are started at the same time, from Figure three From the IL waveform, it can be seen that after the sawtooth inductor current is averaged, a peak current T5 will appear. Therefore, stacking multiple DC / DC converter current waveforms will cause the front-end power supply to provide higher current surge capability.

If the output capacity of the selected power supply is insufficient or the output capacity declines due to long-term use, the power supply will be shut down due to OCP protection

[0006] In order to cope with this phenomenon, the PGOOD signal can be used as the basis signal to inform the next-level DC / DC converter, which means that PGOOD is used as the EN signal input of the next-level DC / DC converter, but as figure 2 As shown in the PGOOD signal diagram, this signal does not really avoid the IL peak current, so the power supply must still take part of the current surge

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