LED6000 datasheet(27/49 Pages) STMICROELECTRONICS

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LED6000

Application notes - step-down conversion

Equation 12

In order to guarantee a maximum current ripple in every condition, Equation 12 must be

evaluated in case of maximum input voltage, assuming VOUT fixed.

Increasing the value of the inductance helps to reduce the current ripple but, at the same

time, strongly impacts the converter response time in case of high frequency dimming

requirements. On the other hand, with a lower inductance value the regulator response time

is improved but the power conversion efficiency is impacted and the output capacitor must

be increased to limit the current ripple flowing through the LEDs.

As usually, the L-CO choice is a trade-off among multiple design parameters.

5.3

Compensation strategy

The compensation network must assure stability and good dynamic performance. The loop

of the LED6000 is based on the voltage mode control. The error amplifier is an operational

amplifier with high bandwidth. So, by selecting the compensation network the E/A is

considered as ideal, that is, its bandwidth is much larger than the system one.

Figure 16. Switching regulator control loop simplified model

OUT

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LED6000 데이터시트(PDF) 27 Page - STMicroelectronics