SC668 datasheet(27/46 Pages) SEMTECH

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SC668

Definition of Registers and Bits

Backlight Enable Register (00h)

The bits of register 00h are used to enable individual back-

light current sinks BL1 through BL6.

BL6EN through BL1EN [D5:D0]

These bits are used to enable current sinks which control

backlight current. When enabled, the current sinks will

regulate the backlight current set by the corresponding

backlight current register.

Bank Enable Register (01h)

The bits of register 01h are multi-function bits. The func-

tion of bits D3 through D0 depend upon the state of bits

D5 and D4. Bits D3 through D0 may be used to turn indi-

vidual banks on and off. An alternate function of bits D1

and D0 is to enable and disable backlights BL7 and BL8.

Figure 19 shows how the function of bits D3 through D0

change according to the state of the DIS bit D5 and the EN

bit D4.

DIS [Bit D5]

When writing to register 01h, if DIS bit D5 = 1 and EN bit

D4 = 0, then bits D3 through D0 can each disable one of

four banks. When disabling a bank, all associated BLxEN

bits are automatically overwritten with a zero.

EN [Bit D4]

When writing to register 01h, if EN bit D4 = 1 and DIS bit

D5 = 0, then bits D3 through D0 can each enable one of

four banks. When enabling a bank, all associated BLxEN

bits are automatically overwritten with a one.

BANK4EN through BANK1EN [Bits D3:D0]

The following bits — BANK4EN, BANK3EN, BANK2EN, and

BANK1EN are used to enable or disable individual back-

light banks dependent upon the state of the DIS and EN

bits, D5 and D4. These bits provide no function when both

DIS and EN are equal to one.

BL8EN and BL7EN [Alternate Function for Bits D1:D0]

These bits are used to enable current sinks which control

backlight current for backlights BL7 and BL8. When

enabled, the current sinks will regulate the backlight

current set by the corresponding backlight current

DIS = 0

EN = 0

DIS = 0

EN = 1

DIS = 1

EN = 0

DIS = 1

EN = 1

D3=1 enables bank #4

D2=1 enables bank #3

D1=1 enables bank #2

D0=1 enables bank #1

D3=1 does nothing

D2=1 does nothing

D1=1 enables BL8

D0=1 enables BL7

D3=1 does nothing

D2=1 does nothing

D1=1 does nothing

D0=1 does nothing

(1) Bit functions are

active high only, a

zero has no function

Bits [D3:D0] (1)

D3=1 disables bank #4

D2=1 disables bank #3

D1=1 disables bank #2

D0=1 disables bank #1

Figure 19 — Multi-function Bits of Register (01h)

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