Linear voltage regulators will face power consumption problems, and switching methods have noise problems. The conversion method chosen by the LED driver depends on the application.
What conversion method
Converting voltage through a linear regulator will face power consumption problems. This method is more suitable for conversion circuits that need to avoid noise (such as car audio) and therefore cannot use switching methods. The characteristic of the switching method is that the conversion efficiency is very high, but it also has the problem of noise, so the choice of conversion method depends on the application.
Generally, the efficiency of the charge pump drive mode will change with the change of the input voltage. In the application with a large voltage change range, the efficiency is relatively low; while in the application with a small voltage change range, only when the input and output voltage When the time is an integer multiple relationship, its efficiency can reach its maximum, but it is difficult to achieve in the practical application of battery power. On the other hand, the conversion efficiency of the inductor is less affected by voltage, and its application limit is less than that of the charge pump, so the current conversion circuit mostly uses the inductance method.
How to evaluate performance
Objectively speaking, the performance of the ic driver should be based on different applications and cannot be generalized. For example, the application of decorative lamps requires high control of RGB color changes, and this performance becomes the main indicator, but this is not required in monochrome applications. Another example is the application of small spaces that requires heat dissipation capacity; in automotive lighting replacement applications, it requires both the performance of a smooth combination with the original circuit system and high reliability; in display applications such as nb, for multiple strings of leds Brightness equalization control requires the driver IC to accurately control the current on each branch. For example, Maxim ’s product control accuracy can reach 3%; projector applications require high-efficiency drive circuits, the ability to quickly adjust brightness and thermal protection. Capability; in alternative applications, performance is more reflected in the entire program rather than a single driver IC. In general, device integration, control quantity, response speed, fault diagnosis, heat resistance, etc. are all performance price references.
Generally, the purpose of high integration is to improve performance, but at high power, high integration will increase the chip area in order to meet the large current, and increase the cost while also facing the problem of heat dissipation, so how to balance power and integration The relationship is driven by the issues facing ic design. Drive IC to improve the chip process to meet the cost, while improving packaging to solve the problem of heat dissipation.
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