VT5365

Design notes

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2.7

Driving the navigation LED

The VT5365 provides an output (NAV_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 4 on page 8). The maximum current through the LED is controlled by a

resistor (R9 on the reference schematic).

Note:

The navigation LED is used in a non-continuous mode. The duty cycle of the LED is varied

by the exposure controller inside the VT5365 and has a maximum value of 40% (on very

dark surfaces).