Design notes

VT5366

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3.4

Driving the navigation LED

The VT5366 provides an output (TRK_LED) to drive the LED that is used to illuminate the

mousing surface. This output is active HIGH but cannot be used to drive the navigation LED

directly. An external NPN bipolar transistor is recommended as shown in the reference

schematic (

Figure 6). The maximum current through the LED is controlled by a resistor (R1

on the Reference Schematic).

Note:

The navigation LED, controlled by the VT5366, is used in a non-continuous mode. The duty

cycle of the LED is varied by the exposure controller inside the VT5366 and has a maximum

value of 40 % (on very dark surfaces).