SC621A_09 Datasheet, PDF (18/24 Pages) Semtech Corporation – LED Light Management Unit Charge Pump, 4 LEDs, 400mA Flash LED, Dual LDOs, and I2C Interface

SC621A
Register Map
Address
D7
D6
0x00
FADE_1 FADE_0
0x01
0⁽¹⁾
0⁽¹⁾
0x02
0⁽¹⁾
0⁽¹⁾
0x03
0⁽¹⁾
LDO2_2
Notes:
(1) 0 = always write a 0 to these bits
D5
FADE_EN
0⁽¹⁾
0⁽¹⁾
LDO2_1
D4
D3
D2
D1
D0
Reset
Value
BL_4
BL_3
BL_2
BL_1
BL_0
0x00
0⁽¹⁾
BLEN_4 BLEN_3 BLEN_2 BLEN_1 0x00
FLTO
FL_2
FL_1
FL_0 FL/SPLB 0x10
LDO2_0 LDO1_3 LDO1_2 LDO1_1 LDO1_0 0x00
Description
Backlight
Current
Control
Backlight
Enable Control
Flash/Spotlight
Control
LDO Control
Register and Bit Definitions
Backlight Current Control Register (0x00)
This register is used to set the currents for the backlight
current sinks, as well as to enable and set the fade step
rate. These current sinks need to be enabled in the
Backlight Enable Control register to be active.
FADE[1:0]
These bits are used to set the rise/fall rate between two
backlight currents as follows:
FADE_1 FADE_0
Fade Feature
Rise/Fall Rate
(ms/step)
0
0
32
0
1
24
1
0
16
value to a new value set by bits BL[4:0] at a rate of 8ms to
32ms per step. A new backlight level cannot be written
during an ongoing fade operation, but an ongoing fade
operation may be cancelled by resetting the fade bit.
Clearing the fade bit during an ongoing fade operation
changes the backlight current immediately to the value
of BL[4:0]. The number of counts to complete a fade
operation equals the difference between the old and new
backlight values to increment or decrement the BL[4:0]
bits. If the fade bit is cleared, the current level will change
immediately without the fade delay. The rate of fade may
be changed dynamically, even while a fade operation is
active, by writing new values to the FADE_1 and FADE_0
bits. The total fade time is determined by the number of
steps between old and new backlight values, multiplied
by the rate of fade in ms/step. The longest elapsed time
for a full scale fade-out of the backlight is nominally 1.024
seconds when the default interval of 32ms is used.
1
1
8
The number of steps in changing the backlight current will
be equal to the change in binary count of bits BL[4:0].
FADE_EN
This bit is used to enable or disable the fade feature. When
the fade function is enabled and a new backlight current
is set, the backlight current will change from its current
18