LM3530 Datasheet, PDF (31/50 Pages) National Semiconductor (TI) – High Efficiency White LED Driver with Programmable Ambient Light Sensing Capability and I2C Compatible Interface

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LM3530
SNVS606L – JUNE 2009 – REVISED DECEMBER 2014
MSB
ALS Resistor Select Register
Address 0x41, Default Value 0x00
LSB
Bit 7
ALSR2A
Bit 6
Bit 5
ALSR2B ALSR2C
Bit 4
ALSR2D
Bit 3
ALSR1A
Bit 2
ALSR1B
Bit 1
ALSR1C
Bit 0
ALSR1D
Figure 45. ALS Resistor Select Register
Table 9. ALS Resistor Select Register Description (0x41)
Bit 7
(ALSR2A)
Bit 6
(ALSR2B)
Bit 5
(ALSR2C)
0000 = ALS2 is high impedance
0001 = 13.531 kΩ (73.9 µA at 1 V)
0010 = 9.011 kΩ (111 µA at 1 V)
0011 = 5.4116 kΩ (185 µA at 1 V)
0100 = 2.271 kΩ (440 µA at 1 V)
0101 = 1.946 kΩ (514 µA at 1 V)
0110 = 1.815 kΩ (551 µA at 1 V)
0111 = 1.6 kΩ (625 µA at 1 V)
1000 = 1.138 kΩ (879 µA at 1 V)
1001 = 1.05 kΩ (952 µA at 1 V)
1010 = 1.011 kΩ (989 µA at 1 V)
1011 = 941 Ω (1.063 mA at 1 V)
1100 = 759 Ω (1.318 mA at 1 V)
1101 = 719 Ω (1.391 mA at 1 V)
1110 = 700 Ω (1.429 mA at 1 V)
1111 = 667 Ω (1.499 mA at 1 V)
Bit 4
(ALSR2D)
Bit 3
(ALSR1A)
Bit 2
(ALSR1B)
0000 = ALS2 is high impedance
0001 = 13.531 kΩ (73.9 µA at 1 V)
0010 =9.011 kΩ (111 µA at 1 V)
0011 = 5.4116 kΩ (185 µA at 1 V)
0100 = 2.271 kΩ (440 µA at 1 V)
0101 = 1.946 kΩ (514 µA at 1 V)
0110 = 1.815 kΩ (551 µA at 1 V)
0111 = 1.6 kΩ (625 µA at 1 V)
1000 = 1.138 kΩ (879µA at 1 V)
1001 = 1.05 kΩ (952 µA at 1 V)
1010 = 1.011 kΩ (989 µA at 1 V)
1011 = 941 Ω (1.063 mA at 1 V)
1100 = 759 Ω (1.318 mA at 1 V)
1101 = 719 Ω (1.391 mA at 1 V)
1110 = 700 Ω (1.429 mA at 1 V)
1111 = 667 Ω (1.499 mA at 1 V)
Bit 1
(ALSR1C)
Bit 0
(ALSR1D)
8.6.1.6 Brightness Control Register
The Brightness Register (BRT) is an 8-bit register that programs the 127 different LED current levels (Bits [6:0]).
The code written to BRT is translated into an LED current as a percentage of I_{LED_FULLSCALE} as set via the Full-
Scale Current Select bits (General Configuration Register bits [4:2]). The LED current response has a typical
1000:1 dimming ratio at the maximum full-scale current (General Configuration Register bits [4:2] = (111) and
using the exponential weighted dimming curve.
There are two selectable LED current profiles. Setting the General Configuration Register bit 1 to 0 selects the
exponentially weighted LED current response (see Figure 34). Setting this bit to '1' selects the linear weighted
curve (see Figure 35). Table 2 and Table 3 show the percentage Full-Scale LED Current at a given Brightness
Register Code for both the Exponential and Linear current response.
MSB
Brightness Control Register
Address 0xA0, Default Value 0x7F
LSB
Bit 7
(Not Used)
Bit 6
Data
Bit 5
Data
Bit 4
Data
Bit 3
Data
Bit 2
Data
Bit 1
Data
Bit 0
Data
Figure 46. Brightness Control Register
Bit 7
N/A
Table 10. Brightness Control Register Description (0xA0)
Bit 6
Data (MSB)
Bit 5
Data
Exponential Mapping (see Table 2)
0000000 = LEDs Off
0000001 = 0.08% of Full Scale
:
:
:
1111111 = 100% of Full Scale
Bit 4
Data
Bit 3
Data
Bit 2
Data
LED Brightness Data (Bits [6:0]
Linear Mapping (see Table 3)
0000000 = LEDs Off
0000001 = 0.79% of Full Scale
:
:
:
1111111 = 100% of Full Scale
Bit 1
Data
Bit 0
Data
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