HD66781 Datasheet, PDF (162/196 Pages) Renesas Technology Corp – 720-channel Source Driver for a-Si TFT/Low Temperature Poly-Si TFT Panels with 262,144-color display RAM

HD66781
Preliminary
Ladder resistors and 8 to 1 selector
Block configuration
The block configuration of page 159 consists of two ladder resistors including variable resistors, and 8 to 1
selectors, which select the voltage generated by the ladder resistors, to output the reference voltage for the
grayscale voltage. The γ−correction registers control the variable resistors and the 8 to 1 selectors. Pins
that are connected to a variable resistor are also provided to compensate the variation among the panels.
Variable resistors
There are three kinds of variable resistors for the gradient adjustment (VRHP(N)/VRLP(N)), the amplitude
adjustment (VRP(N)), and the reference adjustment (VDR). The resistance is determined by the gradient
adjustment and amplitude adjustment registers as is shown below.
Table 69
Gradient adjustment
Register
PRP(N)0/1[2:0]
000
001
010
011
100
101
110
111
Resistance
VRHP(N)
VRLP(N)
0R
4R
8R
12R
16R
20R
24R
28R
Amplitude adjustment
Register
VRP(N)0[3:0]
Resistance
VRP(N)0
0000
0R
0001
1R
0010
2R
:
:
:
:
1101
13R
1110
14R
1111
15R
Reference adjustment
Register
VRP(N)1[4:0]
Resistance
VRP(N)1
00000
0R
00001
1R
00010
2R
:
:
:
:
11101
29R
11110
30R
11111
31R
8 to 1 selector
The 8-to-1 selectors select a voltage level generated by the ladder resistors according to the fine adjustment
registers, and output as a reference voltage of either one of the following VIN1 ~ VIN 6. The relationship
between the fine adjustment register and the selected voltage is as follows
Table 70
Contents of Register
PKP(N) 0/1 [2:0]
000
001
010
011
100
101
110
111
Selected Voltage
VINP(N)1 VINP(N)2
KVP(N)1 KVP(N)9
KVP(N)2 KVP(N)10
KVP(N)3 KVP(N)11
KVP(N)4 KVP(N)12
KVP(N)5 KVP(N)13
KVP(N)6 KVP(N)14
KVP(N)7 KVP(N)15
KVP(N)8 KVP(N)16
VINP(N)3
KVP(N)17
KVP(N)18
KVP(N)19
KVP(N)20
KVP(N)21
KVP(N)22
KVP(N)23
KVP(N)24
VINP(N)4
KVP(N)25
KVP(N)26
KVP(N)27
KVP(N)28
KVP(N)29
KVP(N)30
KVP(N)31
KVP(N)32
VINP(N)5
KVP(N)33
KVP(N)34
KVP(N)35
KVP(N)36
KVP(N)37
KVP(N)38
KVP(N)39
KVP(N)40
VINP(N)6
KVP(N)41
KVP(N)42
KVP(N)43
KVP(N)44
KVP(N)45
KVP(N)46
KVP(N)47
KVP(N)48
Rev.0.5, July.31.2003, page 162 of 196