LP5860RKPR datasheet(13/71 Pages) TI

13 / 71 page

The LP5861T 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 (IOUT_MAX × CC/127).

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

8-BIT DC REGISTER

RATIO OF OUTPUT CURRENT TO IOUT_MAX × CC/127

Binary

Decimal

0000 0000

0000 0001

0.39

0000 0010

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:

IOUT (mA) = IOUT_MAX × (CC/127) × (DC/255)

(1)

8.3.2 PWM Dimming

There are several methods to control the PWM duty cycle of each LED dot.

• Individual 8-bit / 16-bit PWM for Each LED Dot

Every LED has an individual 8-bit or 16-bit PWM register that is used to change the LED brightness by PWM

duty. The LP5861T uses an enhanced spectrum PWM (ES-PWM) algorithm to achieve 16-bit depth with high

refresh rate and this can avoid flicker under high speed camera. Comparing with conventional 8-bit PWM,

16-bit PWM can help to achieve ultimate high dimming resolution in LED animation applications.

• 3 Programmable Groups of 8-bit PWM Dimming

The group PWM Control is used to select LEDs into one to three groups where each group has a separate

to select whether the LED dot belongs to one of the three groups or not:

– 00: not a member of any group

– 01: member of group 1

– 10: member of group 2

– 11: member of group 3

• 8-bit PWM for Global Dimming

The Global PWM Control function affects all LEDs simultaneously.

The final PWM duty cycle can be calculated as below:

PWM_Final(8 bit) = PWM_Individual(8 bit) × PWM_Group(8 bit) × PWM_Global(8 bit)

(2)

PWM_Final(16 bit) = PWM_Individual(16 bit) × PWM_Group(8 bit) × PWM_Global(8 bit)

(3)

The LP5861T supports 125-kHz or 62.5-kHz PWM output frequency. The PWM frequency is selected by

configuring the 'PWM_Fre' in Dev_initial register. An internal 32-MHz oscillator is used for generating PWM

outputs. The oscillator’s high accuracy design (ƒOSC_ERR ≤ ± 2%) enables a better synchronization if multiple

LP5861T devices are connected together.

www.ti.com

LP5861T

SNVSCE4 – MAY 2023

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