LP3943ISQ National Semiconductor, LP3943ISQ Datasheet - Page 9

• Manufacturer Part Number: LP3943ISQ
• Description: LED Driver IC
• Manufacturer: National Semiconductor

Specifications of LP3943ISQ

• Driver Case Style: LLP
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• No. Of Pins: 24
• Package / Case: 24-LLP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Application Notes
BINARY FOMAT FOR INPUT REGISTERS (READ ONLY) — ADDRESS 0x00 and 0x01
X = don’t care
X = don’t care
BINARY FORMAT FOR FREQUENCY PRESCALER AND PWM REGISTERS — ADDRESS 0x02 to 0x05
PSC0 register is used to program the period of DIM0.
DIM0 = (PSC0+1)/160
The maximum period is 1.6s when PSC0 = 255.
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.
PSC1 register is used to program the period of DIM1.
DIM1 = (PSC1 + 1)/160
The maximum period is 1.6s when PSC1 = 255.
Address (Hex)
Bit #
Default value
Bit #
Default value
Bit #
Default value
Bit #
Default value
Bit #
Default value
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
LED15
Input 1
Input 2
PSC0
PWM0
PSC1
PWM1
LS0
LS1
LS2
LS3
LED7
7
X
X
7
Register Name
7
0
7
1
7
0
(Continued)
LED14
LED6
6
X
6
X
6
0
6
0
6
0
TABLE 1. LP3943 REGISTER TABLE
Read Only
Read Only
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
LED13
LED5
Address 0x03 (PWM0)
Address 0x02 (PSC0)
Address 0x04 (PSC1)
X
5
5
X
Address 0x00
Address 0x01
5
0
5
0
5
0
Read/Write
9
LED4
LED12
X
4
4
X
4
0
4
0
4
0
LED3
LED11
LED0–7 Input Register
LED8–15 Input Register
Frequency Prescaler 0
PWM Register 0
Frequency Prescaler 1
PWM Register 1
LED0–3 Selector
LED4–7 Selector
LED8–11 Selector
LED12–15 Selector
X
3
X
3
3
0
3
0
3
0
LED2
LED10
X
2
X
2
0
2
0
2
0
Register Function
2
LED1
LED9
1
X
1
0
1
0
1
0
X
1
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LED0
LED8
X
0
X
0
0
0
0
0
0
0