LM3538

SNVS674A – JUNE 2011 – REVISED MAY 2013

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Table 1. ALS Resistor Values (continued)

r_als[4]

r_als[3]

r_als[2]

r_als[1]

r_als[0]

RALS (typ) Value

Unit

1

1

0

0

1

0.806

k

Ω

1

1

0

0

0

0.840

k

Ω

1

0

1

1

1

0.876

k

Ω

1

0

1

1

0

0.916

k

Ω

1

0

1

0

1

0.960

k

Ω

1

0

1

0

0

1.01

k

Ω

1

0

0

1

1

1.06

k

Ω

1

0

0

1

0

1.12

k

Ω

1

0

0

0

1

1.19

k

Ω

1

0

0

0

0

1.26

k

Ω

0

1

1

1

1

1.34

k

Ω

0

1

1

1

0

1.44

k

Ω

0

1

1

0

1

1.55

k

Ω

0

1

1

0

0

1.68

k

Ω

0

1

0

1

1

1.83

k

Ω

0

1

0

1

0

2.02

k

Ω

0

1

0

0

1

2.24

k

Ω

0

1

0

0

0

2.52

k

Ω

0

0

1

1

1

2.88

k

Ω

0

0

1

1

0

3.36

k

Ω

0

0

1

0

1

4.03

k

Ω

0

0

1

0

0

5.00

k

Ω

0

0

0

1

1

6.72

k

Ω

0

0

0

1

0

10.1

k

Ω

0

0

0

0

1

20.2

k

Ω

0

0

0

0

0

HighZ

--

Automatic Gain Change

GPO pins of the LM3538 can be configured to serve as a gain control interface for sensors with HW controlled

gain, like ROHM BH1600-series. Please see Table 2. LM3538 changes sensor gain automatically based on

ambient light intensity changes.

Table 2. Sensor Gain Control

REGISTER SETTING

OUTPUT PIN STATUS

GPO1

GPO2

autogain_en = "0"

Can be set to "1" or "0" with REG 52H, bit

Can be set to "1" or "0" with REG 52H, bit

gpo1

gpo2

autogain_en = "1" (enables autogain

0

1

functionality)

LOW GAIN

autogain_en = "1" (enables autogain

1

0

functionality)

HIGH GAIN

14

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