LM3538

SNVS674A – JUNE 2011 – REVISED MAY 2013

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Table 5. Control Register Map (continued)

Hex

Read/W

Default Value

Register Name

Bit(s)

Bit Mnemonic and Description

Addr.

rite

After Reset

autogain_en

'1' = Enables autogain for the external ambient light sensor.

[7]

R/W

0xxxxxxx

'0' = disables autogain and GPO's are controlled by the gpo1 and

gpo2 -bits. See Table 2 for details.

sbias_en

'1' = External sensor power output enabled.

'0' = External sensor power output disbaled.

[6]

R/W

x0xxxxxx

Note: '1' -> GPOs will behave as push-pull CMOS outputs

referenced to voltage on SBIAS. '0' -> GPOs will act as open-drain

outputs (default).

sbias_volt

Sensor bias output voltage selection.

[5]

R/W

xx0xxxxx

'1' = 3.0V output voltage.

'0' = 2.4V output voltage.

cp_en

52

ALS CONFIG

Writing = '1' to this register bit enables the Charge-Pump block.

[3]

R/W

xxxx0xxx

Forces the LM3538 to operate in the gain of 1.5x. This mode DOES

NOT require the Dx current sinks to be enabled for operation.

pass_en

Writing = '1' to this register bit forces the LM3538 to operate in the

[2]

R/W

xxxxx0xx

gain of 1x (pass-mode). This mode DOES NOT require the Dx

current sinks to be enabled for operation. Note: 1.5x gain (cp_en bit)

has a higher priority.

gpo1

'0' = GPO1 pin state is low. '1' = GPO1 pin state is high. Effective

[1]

R/W

xxxxxx0x

only when the autogain is disabled.

(1)

gpo2

'0' = GPO2 pin state is low. '1' = GPO2 pin state is high. Effective

[0]

R/W

xxxxxxx0

only when the autogain is disabled.

(1)

ALS ZONE

zb0

60

[7:0]

R/W

00110011

BOUNDARY#0

Sets Zone0 to Zone1 transition trip point

ALS ZONE

zb1

61

[7:0]

R/W

01100110

BOUNDARY#1

Sets Zone1 to Zone2 transition trip point

ALS ZONE

zb2

62

[7:0]

R/W

10011001

BOUNDARY#2

Sets Zone2 to Zone3 transition trip point

ALS ZONE

zb3

63

[7:0]

R/W

11001100

BOUNDARY#3

Sets Zone3 to Zone4 transition trip point

LtoH

ALS LOW to HIGH

64

[7:0]

R/W

00001011

Sets the trip point for low gain to high gain transition. Effective only

TP

when autogain = '1'.

ALS ZONE

zb3to2

65

BOUNDARY Z3 to

[7:0]

R/W

00010000

Zone3 to Zone2 transition trip point when the autogain is enabled.

Z2

ALS BRIGHTNESS

z0b

70

[6:0]

R/W

x0111100

ZONE#0

Sets the Zone Brightness code for Zone0.

ALS BRIGHTNESS

z1b

71

[6:0]

R/W

x1001101

ZONE#1

Sets the Zone Brightness code for Zone1.

ALS BRIGHTNESS

z2b

72

[6:0]

R/W

x1011001

ZONE#2

Sets the Zone Brightness code for Zone2.

ALS BRIGHTNESS

z3b

73

[6:0]

R/W

x1100110

ZONE#3

Sets the Zone Brightness code for Zone3.

ALS BRIGHTNESS

z4b

74

[6:0]

R/W

x1110010

ZONE#4

Sets the Zone Brightness code for Zone4.

(1)

VOUT_S = SBIAS pin output voltage. The voltage level of the GPOs depends on the sbias_en-bit: '1'; GPOs will behave as push-pull

outputs and will reference the high-side to the voltage of SBIAS. '0'; GPOs will act as open-drain outputs (default). In the open-drain

configuration, they can be high-side referenced to any voltage equal or less than the VIN_A of the LM3538. Output High Level (VOH)

specification is valid only for push-pull -type outputs.

22

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