CXA2108AQ
Nv 1 and emitting duty
Luminance data (Dv)
D9 to 0
Brightness (D3 to 0) = 0000
Brightness (D3 to 0) = 0111
Brightness (D3 to 0) = 1111
D9
D0
Emitting duty [%]
Emitting duty [%]
Emitting duty [%]
Nv
Nv
Nv
0
1
2
:
512
:
0
0
8
16
0
0
16
32
0
0000000000
0000000001
0000000010
0.006
0.012
:
3.125
:
0.049
0.098
:
25.00
:
0.098
0.195
:
50.00
:
:
:
:
4096
:
8192
:
1000000000
:
1111111111
1023
6.244
8184
49.95
16368
99.90
1
Nv = Tv/TCLK = Dv × Db
Table 3. Relationship Between Luminance Data, Brightness Data and Emitting Duty
3. Drive current data (Dd)
Even when driving LEDs of the same color with the same current value, individual differences in characteristics
result in an uneven emitting intensity. In addition, the required current value also differs according to the
emitting color (RGB). That is to say, the necessary current differs for each LED. This drive current IOUT
corresponds to the amplitude of the IOUT output PWM waveform as shown in Fig. 1. The CXA2108AQ can set
this current independently for each LED using Coarse Adj. (2 bits: D8, D9) and Fine Adj. (8 bits: D0 to D7). The
maximum values of the drive current (Io (FFh): IOUT @ D0 to D7 = FFh) are varied in 4 levels by Coarse Adj.
(2 bits: D8, D9). The minimum drive current (Io (00h): IOUT @ D0 to D7 = 00h) is approximately
0mA,regardless of the Coarse Adj. range. The range from the minimum to the maximum drive current can be
set at an accuracy of 8 bits (D0 to D7 = 256 steps).
Note that this drive current is generated using the Iref described in 6. as the reference.
The relationship between the Fine Adj. (8 bits: D0 to D7) data and the drive current, and the drive current data
(D0 to D9) to drive current correspondence table are shown below.
Drive current
Io (FFh)
(Maximum drive current)
•
•
(256 steps)
1 LSB
• •
= Io (FFh)/255
Io (00h) ≈ 0
01h
00h
FEh
FFh
(Minimum drive current)
Fine Adj. (8 bits: D0 to D7) data
Fig. 2. Relationship Between Fine Adj. (8 bits: D0 to D7) Data and Drive Current
Drive current
Drive current data (Dd)
D7 to 0
D9
0
D8 D9
D8
1
D9
1
D8
1
D9
1
D8
0
D7
D0
0
0
0
:
0
:
0
:
Minimum drive current Io (00h)
00000000 (00h)
0
:
:
400 × Iref 800 × Iref
1600 × Iref
10000000 (80h)
:
1200 × Iref
:
:
:
:
800 × Iref 1600 × Iref
3200 × Iref Maximum drive current Io (FFh)
11111111 (FFh)
2400 × Iref
Table 4. Drive Current Data (D0 to D9) to Drive Current Correspondence Table
– 13 –
SONY [ SONY CORPORATION ]
