LP3958 Datasheet, PDF (26/36 Pages) National Semiconductor (TI) – Lighting Management Unit with High Voltage Boost Converter

LP3958
SNVS423C – JANUARY 2006 – REVISED MARCH 2013
LP3958 Register Bit Explanations
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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
RW
R
–0,–1
Bit Accessibility
Read/write
Read only
Condition after POR
CONTROL REGISTER (00H) – KEYPAD LEDS CONTROL REGISTER
D7
KEYP_PWM
RW - 0
D6
EN_KEYP
RW - 0
D5
CC_SW
RW - 1
D4
R-0
D3
K1SW
RW - 0
D2
K2SW
RW - 0
D1
K3SW
RW - 0
D0
R-0
KEYP_PWM
EN_KEYP
CC_SW
K1SW
K2SW
K3SW
Bit 7
Bit 6
Bit 5
Bit 3
Bit 2
Bit 1
0 - Internal KEYPAD PWM control disabled
1 - Internal KEYPAD PWM control enabled
0 – KEYPAD outputs disabled
1 – KEYPAD outputs enabled
0 – Constant current sink mode
1 – Switch mode
0 – KEYPAD1 disabled
1 – KEYPAD1 enabled
0 – KEYPAD2 disabled
1 – KEYPAD2 enabled
0 – KEYPAD3 disabled
1 – KEYPAD3 enabled
KEYPAD (01H) – KEYPAD BALANCE AND BRIGHTNESS CONTROL REGISTER
D7
R-0
D6
RW - 0
D5
BALANCE[2:0]
RW - 0
D4
RW - 0
D3
RW - 0
D2
BRIGHT[2:0]
RW - 0
D1
RW - 0
D0
OVL
RW - 0
BALANCE[2:0]
BRIGHT[2:0]
OVL
Bits 6-4
Bits 3-1
Bit 0
PWM balance for KEYPAD outputs
PWM brightness control for KEYPAD outputs
0 – Overlapping mode disabled
1 – Overlapping mode enabled
KEYPAD MAX CURRENT (02H) – MAXIMUM KEYPAD CURRENT CONTROL REGISTER
D7
R-0
D6
R-0
D5
D4
IK1[1:0]
RW - 0
RW - 0
D3
D2
IK2[1:0]
RW - 0
RW - 0
D1
D0
IK3[1:0]
RW - 0
RW - 0
IK1,2,3[1:0]
00
01
10
11
Maximum current for KEY1,2,3 driver
Maximum output current
0.25 × I_MAX
0.50 × I_MAX
0.75 × I_MAX
1.00 × I_MAX
26
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