AN4460 datasheet(37/54 Pages) STMICROELECTRONICS

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AN4460

Measurements

This section reports several measurement results validating the STEVAL-ILL057V1

demonstration board performance.

8.1

Output current precision for different current setup

Figure 14 shows the current flow through the LEDs, measured with a current probe on all

four channels. The operating current of all channels is the point 0 in Table 1 on page 14

(245 mA mean). Note the channel has delayed startup point and the current precision on all

channels displayed. R1 is channel zero, R2 is channel two, R3 is channel three and 3 is

channel four. The dimming periods, same for all channels, is ~5 ms (193 Hz).

Figure 14. Current regulation - 4 channels at 245 mA

Figure 15 represents the different current regulation on the same channel and at the same

dimming level. The current has changed using the “lc” command using, as second

parameter, the index of the expected current. The vertical grid resolution is 100 mA/div. See

Table 1 on page 14 for the index and current relation.

AM16714v1

AN4460 Datasheet(PDF) 37 Page - STMicroelectronics