米6体育平台手机版

ZHCSOR4 December 2021 LP5862

PRODUCTION DATA

封装选项

机械数据 (封装 | 引脚)

DBT|38
- MPDS368A
RSM|32
- MPQF195B

散热焊盘机械数据 (封装 | 引脚)

RSM|32
- QFND112H

订购信息

zhcsor4_oa

8.3.2 Analog Dimming (Current Gain Control)

Analog dimming of LP5862 is achieved by configuring the current gain control. There are several methods to control the current gain of each LED.

Global 3-bits Maximum Current (MC) setting without external resistor
3 Groups of 7-bits Color Current (CC) setting
Individual 8-bit Dot Current (DC) setting

Global 3-Bits Maximum Current (MC) Setting

The MC is used to set the maximum current, I_{OUT_MAX}, for each current sink, and this current is the maximum peak current for each LED dot. The MC can be set with 3 bits (8 steps) from 3 mA to 50 mA. When the device is powered on, the MC data is set to default value, which is 15 mA.

For data refresh Mode 1, MC data is effective immediately after new data updated. For Mode 2 and Mode 3, to avoid unexpected MC data change during high speed data refreshing, MC data must be changed when all channels are off and new MC data is only be updated when the 'Chip_EN' bit in Chip_en register is set to 0, and after the 'Chip_EN' returns to 1, the new MC data is effective. 'Down_Deghost' and 'Up_Deghost' in Dev_config3 work in the similar way with MC.

Table 8-1 Maximum Current (MC) Register Setting

3-BITS MAXIMUM_CURRENT REGISTER		I_{OUT_MAX}
Binary	Decimal	mA
000	0	3
001	1	5
010	2	10
011 (default)	3 (default)	15 (default)
100	4	20
101	5	30
110	6	40
111	7	50

3 Groups of 7-Bits Color Current (CC) Setting

The LP5862 device is able to adjust the output current of three color groups separately. For each color, it has 7-bits data in 'CC_Group1', 'CC_Group2', and 'CC_Group3'. Thus, all color group currents can be adjusted in 128 steps from 0% to 100% of the maximum output current, I_{OUT_MAX}.

The 18 current sinks have fixed mapping to the three color groups:

CC-Group 1: CS0, CS3, CS6, CS9, CS12, CS15
CC-Group 2: CS1, CS4, CS7, CS10, CS13, CS16
CC-Group 3: CS2, CS5, CS8, CS11, CS14, CS17

Table 8-2 3 Groups of 7-bits Color Current (CC) Setting

7-BITS CC_GROUP1/CC_GROUP2/CC_GROUP3 REGISTER		RATIO OF OUTPUT CURRENT TO I_{OUT_MAX}
Binary	Decimal	%
000 0000	0	0
000 0001	1	0.79
000 0010	2	1.57
- - -	- - -	- - -
100 0000 (default)	64 (default)	50.4 (default)
- - -	- - -	- - -
111 1101	125	98.4
111 1110	126	99.2
111 1111	127	100

Individual 8-bit Dot Current (DC) Setting

The LP5862 can individually adjust the output current of each LED by using dot current function through DC setting. The device allows the brightness deviations of the LEDs to adjusted be individually. Each output DC is programmed with a 8-bit depth, so the value can be adjusted with 256 steps within the range from 0% to 100% of (I_{OUT_MAX} × CC/127).

Table 8-3 Individual 8-bit Dot Current (DC) Setting

8-BIT DC REGISTER		RATIO OF OUTPUT CURRENT TO I_{OUT_MAX} × CC/127
Binary	Decimal	%
0000 0000	0	0
0000 0001	1	0.39
0000 0010	2	0.78
- - -	- - -	- - -
1000 0000 (default)	128 (default)	50.2 (default)
- - -	- - -	- - -
1111 1101	253	99.2
1111 1110	254	99.6
1111 1111	255	100

In summary, the current gain of each current sink can be calculated as below:

Equation 3. I_OUT (mA) = I_{OUT_MAX} × (CC/127) × (DC/255)

For time-multiplexing scan scheme, if the scan number is N, each LED dot's average current I_AVG is shown as below:

Equation 4. I_AVG (mA) = I_OUT / N = I_{OUT_MAX} × (CC/127) × (DC/255)/N