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AS1112

Datasheet - D e t a i l e d D e s c r i p t i o n

Figure 12. Greyscale Data Input Timing Diagram

Status Information Data (SID)

The AS1112 contains an integrated status information register, which can be accessed in greyscale mode (MODE =

GND). Once the LD signal latches the data into the greyscale register, the input shift register data is replaced with sta-

tus information data (see Figure 13).

Open, shorted LED, temperature warning and overtemperature flags as well as the dot-correction registers can be

read out at pin SDO. The status information data packet is 192 bits wide. Bits 191:176 and 31:16 contain the open LED

detection status of each channel (either 191:176 or 31:16 can be used for readout). Bit 175 contains the thermal error

flag status. Bit 174 contains the temperature warning flag. Bits 167:72 contain the data of the dot-correction register. Bit

15:0 contains the LED shorted flags. The remaining bits are reserved. The complete status information data packet is

shown in Figure 13.

Figure 13. Status Information Data Packet Format

Greyscale PWM Operation

The falling edge of the OEN signal initiates a greyscale PWM cycle. The first GSCLK pulse after the falling edge of

OEN increments the greyscale counter by one and switches on any OUTn whose greyscale value does not equal zero.

Each subsequent rising edge of GSCLK increments the greyscale counter by one.

The AS1112 compares the greyscale value of each OUTn channel with the greyscale counter value. All OUTn whose

greyscale values equal the counter values are switched off. A OEN = 1 signal after 4096 GSCLK pulses resets the

greyscale counter to zero and completes a greyscale PWM cycle (see Figure 14).

DCn-1

MSB

DCn-1

MSB-1

x

x

SIDn

MSB

SIDn

MSB-1

SIDn

MSB-2

SIDn

LSB

GSn

LSB

GSn

MSB

DCn-1

LSB

GSn+1

MSB

GSn+1

LSB

MODE

LD

SDI

CLK

SDO

1st Greyscale Mode

Data Input Cycle After Dot Correction Input

Following Greyscale Mode

Data Input Cycle

Dot Correction Mode

Data Input Cycle

96

1

192

1

192

x

SIDn

MSB

LSD

X

DC0.

DC15.

X

TWF

TEF

LOD0

LOD15

LSB

DC Values

...

...

...

Open LED

Detect

Overtempera-

ture

MSB

191

176

175

168

167

72

71

0:15

Bit #

Description

Bit #

Description

0:15

LED Short Detection, LSD

168:173

Undefined

16:31

LED Open Detection (Optional, same as bits 176:191), LOD

174

Temperature Warning Flag (TWF, 125ºC, typ)

32:71

Undefined

175

Temperature Error Flag (TEF, 150ºC, typ)

72:167

Dot Correction Readback (16 x 6 Bit)

176:191

LED Open Detection, LOD

16:31

LOD

174

...