LP5890 datasheet(16/72 Pages) TI

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Table 8-1. Stackable With Different SCAN_REV Value (continued)

LED Matrix Physical Line

Device Line Switch Pin (SCAN_REV = 1)

Device Line Switch Pin (SCAN_REV = 0)

L25

2_LS6

2_LS9

L26

2_LS5

2_LS10

L27

2_LS4

2_LS11

L28

2_LS3

2_LS12

L29

2_LS2

2_LS13

L30

2_LS1

2_LS14

L31

2_LS0

2_LS15

When the LP5890 devices are used in stackable mode, if there are unused line switches, these unused line

switches must be the last line switches of the first or the second device. For example, if there are only 30

scanning lines, and if,

The unused line switches must be 2_LS14, 2_LS15 if SCAN_REV = '0'b, or 2_LS1, 2_LS0 if SCAN_REV = '1'b.

8.3.2 Current Setting

8.3.2.1 Brightness Control (BC) Function

The LP5890 device is able to adjust the output current of all constant-current outputs simultaneously. This

function is called global brightness control (BC). The global BC for all outputs is programmed with a 3-bit

When the 3-bit BC register changes, the gain of output current, GAINBC changes as Table 8-2 below.

Table 8-2. Current Gain Versus BC Code

BC Register (BC)

Current Gain (GAINBC)

000b

24.17

001b

30.57

010b

49.49

011b (default)

86.61

100b

103.94

101b

129.92

110b

148.48

111b

173.23

The maximum output current per channel, IOUTSET, is determined by resistor, RIREF, and the GAINBC. The

voltage on IREF is typically 0.8 V. RIREF can be calculated by Equation 1 below. For noise immunity purpose,

suggest RIREF < 40 kΩ.

+4'(

(G×) =

+4'(

(8)

+4'(

(I#)

+4'(

(8)

1765'6

(I#)

× )#+0($%)

(1)

8.3.2.2 Color Brightness Control (CC) Function

The LP5890 device is able to adjust the output current of each of the three color groups R0-R15, G0-G15, and

B0-B15 separately. This function is called color brightness control (CC). For each color, it has 8-bit data register,

CC_R, CC_G, or CC_B. Thus, all color group output currents can be adjusted in 256 steps from 0% to 100%

of the maximum output current, IOUTSET. The output current of each color, IOUT_R (or G or B), can be calculated by

Equation 2 below.

176

_4(KN ) KN $) =

1765'6

1 + %%_4(KN %%_) KN %%_$)

256

(2)

Table Table 8-3 shows the CC data versus the constant-current against IOUTSET:

LP5890

SLVSGD5 – JULY 2021

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