HD66787 Datasheet, PDF (120/159 Pages) Renesas Technology Corp – 528-channel, One-chip Driver with 262,144-color Display RAM and Power Supply Circuit for Low-temperature Poli-Si TFT (LTPS-TFT) Panels with Incorporat

HD66787
γ-Correction Registers
Register
Groups
Gradient
adjustment
Amplitude
adjustment
Fine adjustment
Positive
Polarity
PRP0 2 to 0
PRP1 2 to 0
VRP0 3 to 0
VRP1 4 to 0
PKP0 2 to 0
PKP1 2 to 0
PKP2 2 to 0
PKP3 2 to 0
PKP4 2 to 0
PKP5 2 to 0
Negative
Polarity
PRN0 2 to 0
PRN1 2 to 0
VRN0 3 to 0
VRN1 4 to 0
PKN0 2 to 0
PKN1 2 to 0
PKN2 2 to 0
PKN3 2 to 0
PKN4 2 to 0
PKN5 2 to 0
Preliminary
Description
Variable resistor VRHP (N)
Variable resistor VRLP (N)
Variable resistor VRP (N)0
Variable resistor VRP (N)1
8-to-1 selector (voltage level of grayscale 1)
8-to-1 selector (voltage level of grayscale 8)
8-to-1 selector (voltage level of grayscale 20)
8-to-1 selector (voltage level of grayscale 43)
8-to-1 selector (voltage level of grayscale 55)
8-to-1 selector (voltage level of grayscale 62)
Ladder resistors and 8-to-1 selector
Block configuration
The block diagram of page 117 consists of two ladder resistors including variable resistors, and 8-to-1
selectors which select the voltage generated by the ladder resistors to output a reference voltage for the
grayscale voltage. The variable resistors and the 8-to-1 selectors are controlled by the γ correction registers.
Pins that are connected to a variable resistor are also provided to compensate the variation among the
panels.
Variable resistor
There are three kinds of variable resistors for the gradient adjustment (VRHP(N)/VRLP(N)), the amplitude
adjustment (1) (VRP(N)0), and the amplitude adjustment (2) (VRP(N)1). The resistance is determined by
the gradient adjustment and amplitude adjustment registers as is shown below.
Gradient adjustment
Contents of 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 (1)
Contents of Register Resistance
VRP(N)0[3:0]
VRP(N)0
0000
0R
0001
2R
0010
4R
••
••
••
••
1101
26R
1111
28R
1111
30R
Amplitude adjustment (2)
Contents of Register Resistance
VRP(N)1[4:0]
VRP(N)1
00000
0R
00001
1R
00010
2R
••
••
••
••
11101
29R
11110
30R
11111
31R
Rev.0.22, May.23.2003, page 120 of 159