SC662 datasheet(27/30 Pages) SEMTECH

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SC662

Main Fade Control (04h)

This register sets the fade status and rate for the main

backlight group.

Bits [D5:D2]

These bits are unused and are always zeros, so the

maximum pulse count for this register is 3.

MFADE1, MFADE0[D1:D0]

These bits are used to enable fade and set the fade rate

between two backlight currents as shown in Table 5.

Table 5 — Main Display Fade Control Bits

MFADE1

MFADE0

Fade Feature Rise�Fall Rate

(ms�step)

OFF

When the fade rate is set to 2, 4, or 6ms and then a new

backlight current is set, the backlight current will change

from its current value to the new value in steps, pausing at

each step for the duration of the fade rate before proceed-

ing to the next step. The exact length of time used to fade

between any two backlight values is determined by multi-

plying the fade rate by the number of steps between the old

and new backlight values. The fade time can be calculated

from the data provided in Table 1 on page 15.

Backlight Grouping Configuration (05h)

This register assigns the LEDs to the backlight bank

configurations.

Bits [D5:D4]

These bits are unused and are always zeros, so the

maximum pulse count for this register is 16.

FSEL [D3]

This bit sets the charge pump clock frequency. FSEL = 0

for 250kHz, and FSEL = 1 for 1MHz. The default state for

this bit is zero.

MB2 and MB0 [D2:D0]

These bits are used to set the number of LED drivers dedi-

cated to each backlight group. This allows the device to

drive up to three different sets of LEDs with different

current settings. Note that any driver assigned to any LED

group can still be disabled independently if not needed.

The code set by these bits determines how the LED drivers

are assigned among the three LED groups according to

the assignments listed in Table 6. Default state for each of

these three bits is zero (all LEDs assigned to main

display).

Table 6 — Backlight Grouping Configuration

MB2 MB1 MB0

Main

Display

LED

Drivers

Sub

Display

LED

Drivers

Third

Display

LED

Drivers

BL1-BL6

BL1-BL3

BL4-BL6

BL1-BL2

BL3-BL4

BL5-BL6

BL1-BL2,

BL5-BL6

BL3

BL4

BL1-BL3

BL4-BL5

BL6

BL1-BL4

BL5-BL6

BL1-BL5

BL6

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