Ver1.0

28

LD1072

16-CH LED DRIVER WITH DOT CORRECTION AND 12-BIT PWM CONTROL

The LD1072 can adjust the brightness of each channel OUTn using a PWM control scheme. The use of 12 bits per

channel results in 4096 different brightness steps, from 0% to 100% brightness. Equation 9 determines the brightness

level for each output n:

Brightness in % = PWMn/4095 X 100

(10)

PWMn = the programmed PWM value for output n (PWMn = 0 to 4095) n = 0 to 15

PWM data for all OUTn

The input shift register enters PWM data into the PWM register for all channels simultaneously. The complete PWM

data format consists of 16 x 12 bit words, which forms a 192-bit wide data packet (see Figure 19). The data packet

must be clocked in with the MSB first.

SETTING PWM

When MOD is set to GND the LD1072 enters the PWM data input mode. The device switches the input

shift register to 192-bit width. After all data is clocked in, a rising edge of the ST signal latches the data

into the PWM register (see Figure 22). New PWM data immediately becomes valid at the rising edge of the

ST signal; therefore, new PWM data should be latched at the end of a PWM cycle when OEB is high. The

first PWM data input cycle after dot correction requires an additional CLK pulse after the ST signal to

complete the PWM update cycle. All PWM data in the input shift register is replaced with status

information data (SID) after updating the PWM register.

MOD

ST

PWM

LSB

PWM n +

1

LSB

DIN

CLK

DO

DC Mode

Data Input

Cycle

First PWM Mode Data

Input Cycle After DC Data Input Cycle

Following PWM Mode Data

Input Cycle

t

h3

t

su3

t

h3

DC

LSB

PW

M

MS

B

PWM +1

MSB

96

1

19

2

19

3

1

19

2

t

su1

t

h1

t

h2

t

su2

DC n

LSB

X

X

PW

M

MS

B

SID

MSB-1

SID

LSB

SID n+1

MSB

t

pd0

t

su2

SID

MS

B

DC

MS

B

Figure 22. PWM Data Input Timing Chart

MSB

PWM

15.11

PWM 15.0

PWM

14.11

PWM 1.0

PWM 0.11

PWM 0.0

LSB

0

11

12

179

180

191

PWM

OUT15

PWM OUT14 – PWM OUT1

PWM OUT0

Figure 21. PWM Data Packet Format