106 lines
3.6 KiB
Plaintext
106 lines
3.6 KiB
Plaintext
* Texas Instruments - lm3532 White LED driver with ambient light sensing
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capability.
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The LM3532 provides the 3 high-voltage, low-side current sinks. The device is
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programmable over an I2C-compatible interface and has independent
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current control for all three channels. The adaptive current regulation
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method allows for different LED currents in each current sink thus allowing
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for a wide variety of backlight and keypad applications.
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The main features of the LM3532 include dual ambient light sensor inputs
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each with 32 internal voltage setting resistors, 8-bit logarithmic and linear
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brightness control, dual external PWM brightness control inputs, and up to
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1000:1 dimming ratio with programmable fade in and fade out settings.
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Required properties:
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- compatible : "ti,lm3532"
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- reg : I2C slave address
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- #address-cells : 1
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- #size-cells : 0
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Optional properties:
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- enable-gpios : gpio pin to enable (active high)/disable the device.
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- ramp-up-us - The Run time ramp rates/step are from one current
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set-point to another after the device has reached its
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initial target set point from turn-on
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- ramp-down-us - The Run time ramp rates/step are from one current
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set-point to another after the device has reached its
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initial target set point from turn-on
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Range for ramp settings: 8us - 65536us
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Optional properties if ALS mode is used:
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- ti,als-vmin - Minimum ALS voltage defined in Volts
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- ti,als-vmax - Maximum ALS voltage defined in Volts
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Per the data sheet the max ALS voltage is 2V and the min is 0V
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- ti,als1-imp-sel - ALS1 impedance resistor selection in Ohms
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- ti,als2-imp-sel - ALS2 impedance resistor selection in Ohms
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Range for impedance select: 37000 Ohms - 1190 Ohms
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Values above 37kohms will be set to the "High Impedance" setting
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- ti,als-avrg-time-us - Determines the length of time the device needs to
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average the two ALS inputs. This is only used if
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the input mode is LM3532_ALS_INPUT_AVRG.
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Range: 17920us - 2293760us
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- ti,als-input-mode - Determines how the device uses the attached ALS
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devices.
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0x00 - ALS1 and ALS2 input average
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0x01 - ALS1 Input
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0x02 - ALS2 Input
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0x03 - Max of ALS1 and ALS2
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Required child properties:
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- reg : Indicates control bank the LED string is controlled by
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- led-sources : see Documentation/devicetree/bindings/leds/common.txt
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- ti,led-mode : Defines if the LED strings are manually controlled or
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if the LED strings are controlled by the ALS.
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0x00 - LED strings are I2C controlled via full scale
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brightness control register
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0x01 - LED strings are ALS controlled
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Optional LED child properties:
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- label : see Documentation/devicetree/bindings/leds/common.txt
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- linux,default-trigger :
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see Documentation/devicetree/bindings/leds/common.txt
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- led-max-microamp : Defines the full scale current value for each control
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bank. The range is from 5000uA-29800uA in increments
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of 800uA.
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Example:
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led-controller@38 {
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compatible = "ti,lm3532";
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#address-cells = <1>;
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#size-cells = <0>;
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reg = <0x38>;
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enable-gpios = <&gpio6 12 GPIO_ACTIVE_HIGH>;
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ramp-up-us = <1024>;
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ramp-down-us = <65536>;
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ti,als-vmin = <0>;
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ti,als-vmax = <2000>;
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ti,als1-imp-sel = <4110>;
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ti,als2-imp-sel = <2180>;
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ti,als-avrg-time-us = <17920>;
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ti,als-input-mode = <0x00>;
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led@0 {
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reg = <0>;
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led-sources = <2>;
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ti,led-mode = <1>;
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led-max-microamp = <21800>;
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label = ":backlight";
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linux,default-trigger = "backlight";
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};
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led@1 {
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reg = <1>;
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led-sources = <1>;
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ti,led-mode = <0>;
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label = ":kbd_backlight";
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};
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};
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For more product information please see the links below:
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https://www.ti.com/product/LM3532
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