LP3958

SNVS423C – JANUARY 2006 – REVISED MARCH 2013

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LP3958 Register Bit Explanations

Each register is shown with a key indicating the accessibility of the each individual bit, and the initial condition:

Table 6. Register Bit Accessibility and Initial Condition

Key

Bit Accessibility

RW

Read/write

R

Read only

–0,–1

Condition after POR

CONTROL REGISTER (00H) – KEYPAD LEDS CONTROL REGISTER

D7

D6

D5

D4

D3

D2

D1

D0

KEYP_PWM

EN_KEYP

CC_SW

K1SW

K2SW

K3SW

RW - 0

RW - 0

RW - 1

R - 0

RW - 0

RW - 0

RW - 0

R - 0

0 - Internal KEYPAD PWM control disabled

KEYP_PWM

Bit 7

1 - Internal KEYPAD PWM control enabled

0 – KEYPAD outputs disabled

EN_KEYP

Bit 6

1 – KEYPAD outputs enabled

0 – Constant current sink mode

CC_SW

Bit 5

1 – Switch mode

0 – KEYPAD1 disabled

K1SW

Bit 3

1 – KEYPAD1 enabled

Bit 2

0 – KEYPAD2 disabled

K2SW

1 – KEYPAD2 enabled

0 – KEYPAD3 disabled

K3SW

Bit 1

1 – KEYPAD3 enabled

KEYPAD (01H) – KEYPAD BALANCE AND BRIGHTNESS CONTROL REGISTER

D7

D6

D5

D4

D3

D2

D1

D0

BALANCE[2:0]

BRIGHT[2:0]

OVL

R - 0

RW - 0

RW - 0

RW - 0

RW - 0

RW - 0

RW - 0

RW - 0

BALANCE[2:0]

Bits 6-4

PWM balance for KEYPAD outputs

BRIGHT[2:0]

Bits 3-1

PWM brightness control for KEYPAD outputs

0 – Overlapping mode disabled

OVL

Bit 0

1 – Overlapping mode enabled

KEYPAD MAX CURRENT (02H) – MAXIMUM KEYPAD CURRENT CONTROL REGISTER

D7

D6

D5

D4

D3

D2

D1

D0

IK1[1:0]

IK2[1:0]

IK3[1:0]

R - 0

R - 0

RW - 0

RW - 0

RW - 0

RW - 0

RW - 0

RW - 0

Maximum current for KEY1,2,3 driver

IK1,2,3[1:0]

Maximum output current

00

0.25 × IMAX

01

0.50 × IMAX

10

0.75 × IMAX

11

1.00 × IMAX

26

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