Low-Power Digital Ambient Light Sensor

with Enhanced Sensitivity

10

Bits in Lux High-Byte register 0x03 give the 4 bits of exponent E3:E0 and 4 most significant bits of the mantissa byte

M7:M4, and represent the lux reading of ambient light. The remaining 4 bits of the mantissa byte M3:M0 are in the Lux

Low-Byte register 0x04 and enhance resolution of the lux reading from the IC.

Exponent (E[3:0]): Exponent bits of the lux reading (0000 to 1110). Note: A reading of 1111 represents an overrange

condition.

Mantissa (M[7:4]): Four most significant bits of mantissa byte of the lux reading (0000 to 1111).

Exponent = 8xE3 + 4xE2 + 2xE1 + E0

Mantissa = 8xM7 + 4xM6 + 2xM5 + M4

A code of 0000 0001 calculates to be 0.4 lux.

A code of 1110 1111 calculates to be 98,304 lux.

A code of 1110 1110 calculates to be 91,751 lux.

If user wants to read both the Lux High-Byte register 0x03 and Lux Low-Byte register 0x04, then the master should

not send a STOP command between the reads of the two registers. Instead a REPEATED START command should

process).

Integration Timer Bits (TIM[2:0])

The TIM[2:0] bits can be used to program the signal integration time.

In automatic mode (MANUAL = 0), integration time is automatically selected by the on-chip algorithm to be either

100ms/200ms/400ms/800ms. In manual mode, integration time can be varied by the user all the way from 6.25ms to

800ms. See Table 7.

Lux High-Byte Register 0x03

Table 7. Integration Time

TIM[2:0]

INTREGRATION

TIME (ms)

COMMENTS

000

800

This is a preferred mode for boosting low-light sensitivity.

001

400

—

010

200

—

011

100

This is a preferred mode for high-brightness applications.

100

50

Manual mode only.

101

25

Manual mode only.

110

12.5

Manual mode only.

111

6.25

Manual mode only.

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

REGISTER

ADDRESS

E3

E2

E1

E0

M7

M6

M5

M4

0x03