SC667 datasheet(28/47 Pages) SEMTECH

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SC667

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 bit D0 is

used to enable and disable backlight BL7. Figure 20 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.

BL7EN [Alternate Function for Bit D0]

This bit is used to enable the current sink which controls

backlight current for backlight BL7. When enabled, the

current sink will regulate the backlight current set by the

corresponding backlight current register.

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 does nothing

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 20 — Multi-function Bits of Register (01h)

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