SC643EVB SEMTECH [Semtech Corporation], SC643EVB Datasheet - Page 23

• Manufacturer Part Number: SC643EVB
• Manufacturer: SEMTECH [Semtech Corporation]

Register Map (continued)
LDO4 Control Register (08h)
This register is used to enable LDO4 and set its output
voltage level. The ENL4 pin must be high for register 08h
to control LDO4. ENL4 has a logical AND function with the
register contents. Therefore, if ENL4 is low, V
regardless of the contents of register 08h.
Bits [D5:D4]
These bits are unused and are always zeroes.
LDO4V3 through LDO4V0 [D3:D0]
These bits are used to set the output voltage of LDO4 as
shown in Table 9.
Fade Control Register (09h)
This register contains the fade enables and rate controls
for both the main display and sub display LED driver
banks.
LDO4V3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
LDO4V2
Table 9 — LDO4 Control Codes
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
LDO4V1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
LDO4V0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
V
3.3V
3.2V
3.1V
3.0V
2.9V
2.8V
2.7V
2.6V
2.5V
2.4V
2.2V
1.8V
1.7V
1.6V
1.5V
OFF
LDO4
LDO4
=0V
MFADE1 and MFADE0 [D2:D1]
These bits are used to set the rise/fall rate between two
backlight currents for the main display as show in Table
10. For the fade feature to be active, the MFADE bit must
be set. The number of steps required to change the back-
light current will be equal to the change in binary count
of bits MBL4 through MBL0.
MFADE [D0]
This bit is used to enable or disable the fade feature.
When MFADE is enabled and a new main backlight
current is set, this current will change from its existing
value to the new value written in MBL[4:0] at the rate
determined by MFADE1 and MFADE0 (in ms/step). A new
setting cannot be written during an ongoing fade opera-
tion, but an on-going fade operation may be cancelled by
writing 0 to the MFADE bit. Clearing the MFADE bit during
an ongoing fade operation changes the current immedi-
ately to the value of MBL[4:0]. The number of counts to
complete a fade operation equals the diff erence between
the old and new MBL[4:0] settings. If MFADE is cleared,
the current level will change immediately without the
fade delay. The rate of fade may be changed dynamically
by writing new values to the MFADE1 and MFADE0 bits.
The total fade time is given by the number of steps
between old and new backlight values (see Table 4), mul-
tiplied by the rate of fade in ms/step.
MFADE1
Table 10 — Main Display Fade Control Bits
0
0
1
1
MFADE0
0
1
0
1
Fall Rate (ms/step)
Fade Feature Rise/
32
24
16
8
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