彩电集成电路LA7687A引脚功能
彩电集成电路LA7687A：小信号处理单片集成电路
三洋公司的A6机芯采使用了一种超大规模小信号处理集成电路LA7687A(LA7688)，该集成电路较三洋公司LA7680芯片的主要特点有：
彩色解码电路极为简单
外围引脚元件极少
放弃了惯用于的使用玻璃延迟线组成梳状滤波器
PAL-D彩色解码电路方式改用比较新颖的PAL-S彩色解码方式
整个彩色解码电路基本实现了集成化无可调器件且图像的色彩艳丽
LA7687A的AFC电路不再使用线圈移相而是内部锁相技术可靠性大为提高
LA7687A的亮度对比度色饱和度色调和彩色制式等均采用总线控制方式省去了很多元件生产维修更为方便
该集成电路还把以前不能集成到芯片内部的色度带通滤波器色度陷波器亮度延迟线调频伴音鉴频器集成到了片内，广泛使用PLL锁相环技术和开关电容技术使得A6机芯元件极少。另外LA7687A内部还有中频解调行场及同步信号处理等电路。
引脚序号 |
符 号 |
功 能 |
直流电压V |
对地阻值 |
|
|
红笔接地 |
黑笔接地 |
||||
|
1 |
AV/SECAM SIF IN |
伴音中频输入 |
2.1TV |
6.71k |
6.11k |
|
2 |
ID OUT |
图像识别输出 |
4.5 |
5.210k |
4.710k |
|
3 |
APC1 |
APC滤波1 |
4.1 |
3.210k |
3.210k |
|
4 |
APC2 |
APC滤波2 |
3.6 |
4.310k |
4.310k |
|
5 |
VCO |
图像解调 |
7.1 |
7.810k |
6.910k |
|
6 |
VCO ADJ |
图像解调 |
7.1 |
7.810k |
6.910k |
|
7 |
AFT OUT |
AFT输出 |
4.1 |
5.910k |
5.710k |
|
8 |
VIDEO OUT |
视频输出 |
3.1TV |
1.11k |
11k |
|
9 |
RF AGC |
AGC延迟 |
2.3TV |
5.81k |
6.71k |
|
10 |
INT VIDEO IN |
内视频输入 |
4.1TV |
8.110k |
7.210k |
|
11 |
ACL IN |
对比度调节 |
2.43.5 |
810k |
7.210k |
|
12 |
FIL-REF S-VHS SW |
S端子开关 |
3.7 |
8.110k |
7.210k |
|
13 |
S-CHROMA DC CON |
S端子色度输入 |
4.9 |
8.11k |
7.51k |
|
14 |
EXT VIDEO IN |
外视频输入 |
3.7 |
8.110k |
7.210k |
|
15 |
GND (Y/C/D) |
Y/C/D地 |
0 |
0 |
0 |
|
16 |
VIDEO OUT ABL |
未用 |
3.4 |
8.410k |
6.910k |
|
17 |
COLOR KILLER ON-L |
消色 |
4.8 |
2.610k |
2.510k |
|
18 |
ADDR |
总线1 |
2.2 |
4.710k |
5.110k |
|
19 |
DATA |
总线2 |
2.4 |
4.710k |
5.110k |
|
20 |
V-DRIVER |
场激励输出 |
4.4 |
2.210k |
2.110k |
|
21 |
50/60 |
50/60Hz识别 |
150Hz |
2.310k |
2.310k |
|
22 |
AFC FILTER |
行AFC滤波 |
4.78 |
7.710k |
7.210k |
|
23 |
H-OSC |
行振荡 |
4.19 |
8.210k |
7.210k |
|
24 |
H-VCC |
行供电 |
7.1 |
7.2100 |
5.8100 |
|
25 |
H-DRIVER |
行激励输出 |
1 |
610k |
6.610k |
|
26 |
FBP IN/BGP OUT |
行逆程输入 |
1.26 |
110k |
110k |
|
27 |
H-COIN/CLK OUT |
行一致性检测输出 |
5.1 |
1.910k |
1.910k |
|
28 |
BLK |
底色消隐输入 |
0.3 |
3.21k |
3.21k |
|
29 |
B-IN |
屏显B输入 |
3.22 |
810k |
7.210k |
|
30 |
G-IN |
屏显G输入 |
3.22 |
810k |
7.210k |
|
31 |
R-IN |
屏显R输入 |
3.22 |
810k |
7.210k |
|
32 |
-Y |
Y输出 |
4.454.0 |
8.210k |
6.410k |
|
33 |
B-Y |
B-Y输出 |
5.1 |
6.210k |
6.910k |
|
34 |
G-Y |
G-Y输出 |
5.2 |
6.210k |
6.910k |
|
35 |
R-Y |
R-Y输出 |
5.2 |
6.210k |
6.910k |
|
36 |
B-Y IN |
B-Y输入 |
3.2 |
8.110k |
7.210k |
|
37 |
R-Y IN |
R-Y输入 |
3.2 |
8.110k |
7.210k |
|
38 |
B-Y OUT |
B-Y输出 |
4.3 |
8.210k |
7.210k |
|
39 |
R-Y OUT |
R-Y输出 |
4.3 |
8.210k |
7.210k |
|
40 |
VCC(V/C) |
V/C供电 |
8.1 |
6.6100 |
5.3100 |
|
41 |
CW2 |
晶体2 |
1.4P |
810k |
7.210k |
|
42 |
CW1 |
晶体1 |
3.5P |
810k |
7.210k |
|
43 |
APC FILTER |
APC滤波 |
4.9 |
8.610k |
7.310k |
|
44 |
VCC(SIF) |
中放供电2 |
8.3 |
6.4100 |
5.4100 |
|
45 |
VCC(VIF) |
中放供电1 |
8.1 |
6.6100 |
5.3100 |
|
46 |
IF AGC |
中放AGC滤波 |
4.6 |
8.110k |
7.210k |
|
47 |
IF IN |
中频输入2 |
4 |
1.410k |
1.410k |
|
48 |
IF IN |
中频输入1 |
4 |
1.410k |
1.410k |
|
49 |
IF GND |
中频地 |
0 |
0 |
0 |
|
50 |
RF AGC |
射频AGC输出 |
3.8TV |
2.710k |
2.710k |
|
51 |
AUDIO OUT |
音频输出 |
3.5 |
4.21k |
4.21k |
|
52 |
AUDIO FILTER |
伴音去加重 |
3.5 |
8.210k |
7.210k |
说明测量机型为海信TC2139采用MF10B型万用表