LM3538 datasheet(21/31 Pages) TI2

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LM3538

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SNVS674A – JUNE 2011 – REVISED MAY 2013

Table 5. Control Register Map (continued)

Hex

Read/W

Default Value

Bit(s)

Bit Mnemonic and Description

Addr.

rite

After Reset

rev

[7:6]

00xxxxxx

Stores the silicon revision value. LM3538 = '00'

als_gain

[5]

xx0xxxxx

Gain_status indicator: '1' = high gain, '0' = low gain.

timerflag

[4]

xxx0xxxx

At the end of every countdown, the timer sets the timerflag ='1'. The

ALS ZONE

flag bit is cleared once the 0x40 register has been read.

READBACK

zoneflag

[3]

xxxx0xxx

ALS transition flag. '1' = Transition has occurred. '0' = No transition.

The flag bit is cleared once the 0x40 register has been read.

zone

[2:0]

xxxxx000

ALS Zone information: '000’ = Zone0, ‘001’ = Zone1, ‘010’ = Zone2,

‘011’ = Zone3, ‘100’ = Zone4. Other combinations not used.

ave

Sets averaging time for the ALS sampling. Need two to three

[7:5]

R/W

000xxxxx

averaging periods to make transition decision.‘000’ = 25ms, ‘001’ =

50ms, ‘010’ = 100ms, ‘011’ = 200ms, ‘100’ = 400ms, ‘101’ = 800ms,

‘110’ = 1.6s, ‘111’ = 3.2s.

timer

Pre-defined countdown timer function.

'00' = countdown timer is disabled

'01' = 10s countdown timer is enabled (stick to the highest zone for

10s)

[4:3]

R/W

xxx00xxx

'10' = Always stick to the highest zone the ALS reached

'11' = Always stick to the highest zone the ALS reached.

At the end of every countdown, the timer sets the countdown

timerflag (reg 40H), and after that, a Zone transition to a lower Zone

re-loads the timer and starts the next timer period.

als_en

Enables ALS monitoring. Writing a '1' enables the ALS monitoring

ALS CONTROL

[2]

R/W

xxxxx0xx

circuitry and a '0' disables it. This feature can be enabled without

having the current sinks or charge pump active. The ALS value is

updated in register 0x40 ALS ZONE READBACK.

als_en_a

Enable ALS on Group A. Writing a '1' enables ALS control of diode

[1]

R/W

xxxxxx0x

current and a '0' (default) forces the Group A current to the value

stored in the Group A brightness register. The als_en bit must be set

to a '1' for the ALS block to control the Group A brightness.

als_en_b

Enable ALS on Group B. Writing a '1' enables ALS control of diode

current and a '0' (default) forces the Group B current to the value

stored in the Group B brightness register. The als_en bit must be set

[0]

R/W

xxxxxxx0

to a '1' for the ALS block to control the Group B brightness. The ALS

function for Group B is different than Group A in that the ALS will

only enable and disable the Group B diodes depending on the ALS

zone chosen by the user. Group A utilizes the 5 different zone

brightness registers (Addresses 0x70 to 0x74).

r_als

ALS RESISTOR

[4:0]

R/W

xxx00010

Sets the internal ALS resistor value. See Table 1 for details.

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