AS1112
Datasheet - Detailed Description
Figure 12. Greyscale Data Input Timing Diagram
Dot Correction Mode
Data Input Cycle
1st Greyscale Mode
Data Input Cycle After Dot Correction Input
Following Greyscale Mode
Data Input Cycle
MODE
tH3
tSU3
LD
tH3
GSn
MSB
DCn-1
LSB
GSn
LSB
GSn+1
MSB
GSn+1
LSB
SDI
tH2
tSU1
tSU2
tH0
1
CLK
96
192
1
192
SIDn
MSB-1
DCn-1
MSB-1
DCn-1
MSB
SIDn
MSB-2
SIDn
LSB
SIDn
MSB
SIDn
MSB
SDO
x
x
x
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
MSB
191
LSB
0:15
176
175
174
168
X
167
72
71
X
16:31
LOD
...
...
...
LOD15
...
LOD0
TEF
TWF
DC15.
DC0.
LSD
Open LED
Detect
Overtempera-
ture
DC Values
Bit #
Description
LED Short Detection, LSD
Bit #
168:173
174
Description
0:15
16:31
32:71
72:167
Undefined
LED Open Detection (Optional, same as bits 176:191), LOD
Undefined
Temperature Warning Flag (TWF, 125ºC, typ)
Temperature Error Flag (TEF, 150ºC, typ)
LED Open Detection, LOD
175
Dot Correction Readback (16 x 6 Bit)
176:191
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).
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