TMD27721 datasheet(43/59 Pages) AMSCO

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ams Datasheet, Confidential

Page 43

[v1-20] 2014-Jul-21

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TMD2772/ TMD2772WA − Register Description

Proximity Offset Register (0x1E)

The 8-bit proximity offset register provides compensation for

proximity offsets caused by device variations, optical crosstalk,

and other environmental factors. Proximity offset is a

sign-magnitude value where the sign bit, bit 7, determines if

the offset is negative (bit 7 = 0) or positive (bit 7 = 1). The

magnitude of the offset compensation depends on the

proximity gain (PGAIN), proximity LED drive strength (PDRIVE),

and the number of proximity pulses (PPULSE). Because a

number of environmental factors contribute to proximity

offset, this register is best suited for use in an adaptive

closed-loop control system. See available ams application notes

for proximity offset register application information.

The default value on power up is factory trimmed to provide a

typical proximity offset of 100. This is achieved with no glass or

reflective object above the sensor, and PPULSE=08, PGAIN=10,

PDRIVE=00. If the value is changed during use but power is

removed it will return to the default value on power up.

Figure 49:

Proximity Offset Register

SIGN

MAGNITUDE

Field

Bits

Description (Reset value = trimmed value)

SIGN

Proximity Offset Sign. The offset sign shifts the proximity data

negative when equal to 0 and positive when equal to 1.

MAGNITUDE

6:0

Proximity Offset Magnitude. The offset magnitude shifts the

proximity data positive or negative, depending on the proximity offset

sign. The actual amount of the shift depends on the proximity gain

(PGAIN), proximity LED drive strength (PDRIVE), and the number of

proximity pulses (PPULSE).

TMD27721 Datasheet(PDF) 43 Page - ams AG