VT5365

LED selection

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6

LED selection

6.1

Overview

There are a number of LEDs from a range of suppliers which will work well with the VT5365.

It is the responsibility of the customer to ensure that the chosen LED works in their specific

implementation. There are various price/performance trade-offs that can be made.

6.2

Key LED parameters

For optimal performance, the VT5365 system requires a bright visible RED LED in a

at least 900 mcd at a forward current of 20 mA. The key LED parameters are listed in

Table 4:

6.3

VCSEL & IR illumination

The VT5365 sensor will operate over a wide range of illuminant wavelengths. For devices

operating at approx 850 nm (IR LED or VCSEL), the on-die automatic exposure controller

(AEC) will compensate for the change in sensitivity compared to 640 nm (red LED).

Navigation performance may be improved by increasing the illuminated device drive.

Table 4.

Key LED parameters

Parameter

Recommended value

Notes

Diameter

5 mm

important for fit with lens

Length

8.6 mm

Important for fit with lens

Material

AlInGaP

For long-term reliability

Luminous intensity

(@20 mA)

900 mcd

Minimum value

Viewing angle

Half intensity

Mechanical accuracy

Accuracy of the die positioning within the LED

body

Colour

Red

Wavelength

640 nm +/- 50 nm

Relative Illumination at

sensor plane for a circle

of 1.1 mm diameter

80%

Illumination value required for Red/IR LED and

VCSEL