LM3537_13 Datasheet, PDF (22/33 Pages) Texas Instruments – 8-Channel WLED Driver with Four Integrated LDOs

LM3537
SNVS634B – JUNE 2011 – REVISED MAY 2013
www.ti.com
Hex
Addr.
30
Register Name
OPTIONS
40 ALS ZONE
READBACK
50 ALS CONTROL
51 ALS RESISTOR
Table 5. Control Register Map (continued)
Bit(s)
[7:6]
[5:3]
[2:0]
[7:6]
[5]
[4]
[3]
[2:0]
[7:5]
[4:3]
[2]
[1]
[0]
[4:0]
Read/W Default Value
rite
After Reset
Bit Mnemonic and Description
R/W 00xxxxxx
gt
Charge pump gain transition filter. The value stored in this register
determines the filter time used to make a gain transition in the event
of an input line V_{IN_A} step. Filter Times (typ.) = ‘00’ = 3-6ms, ‘01’ =
0.8-1.5ms, ‘10’ = 20µs, '11' = 1µs,
R/W xx000xxx
rd
Diode current ramp down step time: ‘000’ = 6µs, ‘001’ = 0.77ms,
‘010’ = 1.5ms, ‘011’ = 3ms, ‘100’ = 6ms, ‘101’ = 12ms, ‘110’ = 25ms,
‘111’ = 50ms
R/W xxxxx000
ru
Diode current ramp up step time : ‘000’ = 6µs, ‘001’ = 0.77ms, ‘010’
= 1.5ms, ‘011’ = 3ms, ‘100’ = 6ms, ‘101’ = 12ms, ‘110’ = 25ms, ‘111’
= 50ms
R
00xxxxxx
rev
Stores the silicon revision value. LM3537 = '00'
R
xx0xxxxx
als_gain
Gain_status indicator: '1' = high gain, '0' = low gain.
R
xxx0xxxx
timerflag
At the end of every countdown, the timer sets the timerflag ='1'. The
flag bit is cleared once the 0x40 register has been read.
R
xxxx0xxx
zoneflag
ALS transition flag. '1' = Transition has occurred. '0' = No transition.
The flag bit is cleared once the 0x40 register has been read.
R
xxxxx000
zone
ALS Zone information: '000’ = Zone0, ‘001’ = Zone1, ‘010’ = Zone2,
‘011’ = Zone3, ‘100’ = Zone4. Other combinations not used.
R/W 000xxxxx
ave
Sets averaging time for the ALS sampling. Need two to three
averaging periods to make transition decision.‘000’ = 25ms, ‘001’ =
50ms, ‘010’ = 100ms, ‘011’ = 200ms, ‘100’ = 400ms, ‘101’ = 800ms,
‘110’ = 1.6s, ‘111’ = 3.2s.
R/W xxx00xxx
timer
Pre-defined countdown timer function.
'00' = countdown timer is disabled
'01' = 10s countdown timer is enabled (stick to the highest zone for
10s)
'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.
R/W xxxxx0xx
als_en
Enables ALS monitoring. Writing a '1' enables the ALS monitoring
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.
R/W xxxxxx0x
als_en_a
Enable ALS on Group A. Writing a '1' enables ALS control of diode
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.
R/W xxxxxxx0
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
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/W xxx00010
r_als
Sets the internal ALS resistor value. See Table 1 for details.
22
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