Method for enabling high-power LED constant current driven chip to adapt input voltage changes

Abstract

Disclosed is a method for enabling a high-power LED constant current driven chip to adapt input voltage changes. The input voltage change amplitude in the conventional chip typical application schemeis not greater than minus or plus 10%; if the input voltage change amplitude exceeds the range, the output current precision error is obviously increased; according to the method for enabling the high-power LED constant current driven chip to adapt input voltage changes, when the input voltage VIN is connected, a voltage adjustor high-voltage LDO begins to work to provide a 5V power supply VOUT for an analog control circuit part; when an under-voltage latch unit (UVLO) monitors that the output of the LDO reaches 4V, enabling signals (EN) are transmitted to a biasing circuit module, an overheatprotection circuit module, a logic control circuit module and a driving circuit module; at the moment, the whole system of the chip begins to work, a built-in NLDMOS power device M1 is conduced, andthe current of an inductor L is increased; the current on a sampling resistor RSNS is equal to the current on the inductor L, so that when the current flows through a feedback resistor RSNS, a feedback voltage VSNS is generated; the VSNS is fed back to the interior of the chip through a V<fb> pin, and a reference voltage V<ref> (the designed chip is 200mV) is generated in the V<fb> pin by the chipinternal reference; at the moment, a comparator in the chip performs comparison between the feedback voltage VSNS and the reference voltage V<ref>; if the feedback voltage VSNS is lower than the reference voltage V<ref>, the internal NLDMOS is conducted by the chip, and the conduction time TON is determined by the resistor RON connected with a clt pin and the input voltage VIN; after the conduction time TON is finished, the NLDMOS is switched off for a certain time, wherein the time is called as the minimum switch off time TOFF-MIN (the designed chip minimum switch off time is 200ns); after the minimum switch off time TOFF-MIN is finished, the chip performs comparison between the VSNS and the reference voltage V<ref>; if VSNS is lower than the reference voltage V<ref>, the M1 is conducted, and circulation of the next time is started; and then the feedback voltage VSNS and the reference voltage V<ref> are compared again. The method is used for external environment adaptation of the high-power LED constant current driving chip.

Description

Technical field: [0001] The invention relates to a method for making a high-power LED constant current drive chip adapt to changes in input voltage. Background technique: [0002] With many advantages such as low energy consumption, high luminous efficiency, environmental protection, long service life, safety and reliability, LED has gained a place in the lighting field, and has a growing trend. Similarly, the LED lighting industry has also brought very significant economic and social benefits. . Therefore, the rapid popularization of LED lighting has also led to the vigorous development of the LED driver chip industry, making LED driver chips an important part of the power management circuit market. Since the brightness of LED lighting is closely related to the intensity of its conduction current, constant current drive is the most ideal choice. However, the typical application scheme of traditional chips has higher requirements on the range of input voltage variation, wh...

AI Technical Summary

Problems solved by technology

However, the typical application scheme of traditional chips has higher requirements on the range of input voltage variation, which generally does not exceed ±10%. If the range of input voltage changes exceeds this range, the error of output current accuracy will increase significantly. A high-power LED constant current driver chip to adapt to input voltage changes

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