AS1112
Datasheet - Detailed Description
Power Dissipation
To ensure proper operation of the device, the total power dissipation of the AS1112 must be below the power dissipa-
tion rating of the device package. Total power dissipation is calculated as:
DCn
PD = (VCC x ICC) + (VOUT x IMAX x n x
dPWM)
(EQ 2)
63
Where:
VCC is the device supply voltage;
ICC is the device supply current;
VOUT is the device OUTn voltage when driving LED current;
IMAX is the LED current adjusted by RIREF;
DCn is the maximum dot correction value for OUTn;
n is the number of OUTn driving LED at the same time;
dPWM is the duty cycle defined by pin OEN or the greyscale PWM value.
Operating Modes
The AS1112 operates in two modes (see Table 11). Greyscale operating mode (see Figure 12 on page 13) and the shift
registers are in reset state at power-up.
Table 11. Operating Modes
Mode
Input Shift Register
192-bit
Operating Mode
Greyscale PWM Mode
0
1
96-bit
Dot Correction Data Input Mode
Setting Dot Correction
The AS1112 can perform independent fine-adjustments to the output current of each channel, i.e., dot correction. Dot
correction is used to adjust brightness deviations of LEDs connected to the output channels (OUT0:OUT15).
The device powers up with the following default seetings: DC = 63 and GS = 4095.
The 16 channels can be individually programmed with a 6-bit word. The channel output can be adjusted in 64 steps
from 0 to 100% of the maximum output current (IMAX). The output current for each OUTn channel can be calculated as:
DCn
IOUTn = IMAX x
(EQ 3)
63
Where:
IMAX is the maximum programmable output current for each output;
DCn is the programmed dot correction value for output (DCn = 0 to 63);
n = 0 to 15
Dot correction data are simultaneously entered for all channels. The complete dot correction data format consists of 16
x 6-bit words, which forms a 96-bit serial data packet (see Figure 9). Channel data is put on one by one, and the data
is clocked in with the MSB first.
Figure 9. Dot Correction Data Packet Format
MSB
95
LSB
0
90
89
6
5
...
...
...
DC15.5
DC15.0 DC14.5
DC1.0
DC0.5
DC0.0
DC OUT15
DC OUT14:DC OUT1
DC OUT0
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