VL6180 datasheet(30/73 Pages) STMICROELECTRONICS

30 / 73 page

Functional description

VL6180

30/73

DocID024986 Rev 14

Note:

Cross-talk compensation is only applied to targets above 20 mm. This is to ensure that

cross-talk correction is not applied to near targets where the signal rate is decreasing. The

API sets the cross-talk valid height dependent on scaling factor.



The default is 20mm for scaling 1, 10mm (20/2) for scaling 2 and 7mm (~20/3) for scaling 3.

2.15.5

Cross-talk limit

For proximity ranging (scaling 1), a practical limit for cross-talk is < 3.0 Mcps. This is based

on two factors:

The return rate for a 3% reflective target at 100 mm without glass is typically around 1.5

Mcps. If glass is added with a cross-talk of 3.0 Mcps, the resultant return rate will be 4.5

Mcps. This results in a cross-talk correction factor of x3 so for a 100 mm target the raw

range will be in the region of 30 mm. To ensure the cross-talk valid height restriction is

not breached, the minimum raw range allowing for noise margin is around 30 mm.

A cross-talk correction factor of x3 also means that any range noise will be multiplied

by 3 so noise also becomes a limiting factor.

For extended ranging (scaling 3), a practical limit for cross-talk is < 0.2 Mcps.

2.15.6

Cross-talk vs air gap

Figure 20 shows the typical cross-talk vs air gap using low cross-talk glass. Above 1.5 mm,

the cross-talk rises rapidly.

Figure 20. Cross-talk vs air gap

VL6180 数据表(PDF) 30 Page - STMicroelectronics