LP3944 Datasheet, PDF (9/12 Pages) National Semiconductor (TI) – RGB/White/Blue 8-LED Fun Light Driver

Application Notes (Continued)
TABLE 1. LP3944 REGISTER TABLE
Address (Hex)
Register Name
Read/Write
Register Function
0x00
Input 1
Read Only
LED0–7 Input Register
0x01
Register 1
Read Only
None
0x02
PSC0
R/W
Frequency Prescaler 0
0x03
PWM0
R/W
PWM Register 0
0x04
PSC1
R/W
Frequency Prescaler 1
0x05
PWM1
R/W
PWM Register 1
0x06
LS0
R/W
LED0–3 Selector
0x07
LS1
R/W
LED4–7 Selector
0x08
Register 8
R/W
None
0x09
Register 9
R/W
None
Note: Registers 1, 8 and 9 are empty and non-functional registers. Register 1 is read-only, with all bits hard-wired to zero. Registers 8 and 9 can be written and read,
but the content does ot have any effect on the operation of the LP3944.
BINARY FOMAT FOR INPUT REGISTERS (READ ONLY) — ADDRESS 0x00 and 0x01
Bit #
Default value
X = don’t care
7
X
LED7
6
X
LED6
Address 0x00
5
X
LED5
4
X
LED4
3
X
LED3
2
X
LED2
1
X
LED1
BINARY FORMAT FOR FREQUENCY PRESCALER AND PWM REGISTERS — ADDRESS 0x02 to 0x05
0
X
LED0
Address 0x02 (PSC0)
Bit #
7
6
5
4
3
2
1
0
Default value
0
0
0
0
0
0
0
0
PSC0 register is used to program the period of DIM0.
DIM0 = (PSC0+1)/160
The maximum period is 1.6s when PSC0 = 255.
Address 0x03 (PWM0)
Bit #
7
6
5
4
3
2
1
0
Default value
1
0
0
0
0
0
0
0
PWM0 register determines the duty cycle of DIM0. The LED outputs are LOW (LED on) when the count is less than the value in PWM0 and HIGH (LED off) when
it is greater. If PWM0 is programmed with 0x00, LED output is always HIGH (LED off).
The duty cycle of DIM0 is: PWM0/256
Default value is 50% duty cycle.
Address 0x04 (PSC1)
Bit #
7
6
5
4
3
2
1
0
Default value
0
0
0
0
0
0
0
0
PSC1 register is used to program the period of DIM1.
DIM1 = (PSC1 + 1)/160
The maximum period is 1.6s when PSC1 = 255.
9
www.national.com