tc90a58f TOSHIBA Semiconductor CORPORATION, tc90a58f Datasheet - Page 6

• Manufacturer Part Number: tc90a58f
• Description: 3-channel Ad Converter
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Functions
1. Low-Pass Filter (LPF)
No.
Y (RGB) Signal Cut-off Frequency = = = = 6 MHz
72
73
74
75
76
77
78
79
80
Example:
TC90A58F incorporates a low-pass filter (-3dB) for Y and C signals.
When the system clock is 27 MHz, cut-off frequency is 6 MHz for Y signal and 2.8 MHz for C signal.
When the system clock frequency is higher than 27 MHz, cut-off frequencies are determined as follows:
Pin Name
CKSEL3
CKSEL2
CKSEL1
CKSEL0
CLAMP
RESN
TES2
TES1
TES0
Figure 1 Y Signal LPF Characteristic (system clock = = = = 27 MHz)
System clock frequency = 29.82 MHz
Y signal cut-off frequency: 6 (MHz) ´ (29.82 (MHz) ¸ 27 (MHz)) = approx. 6.63 MHz
Cb, Cr cut-off frequency: 2.8 (MHz) ´ (29.82 (MHz) ¸ 27 (MHz)) = approx. 3.09 MHz
Low-pass filter characteristic for Y and C signals is shown below:
I/O
I
I
I
I
I
I
I
I
I
Clock select
Clock select
Clock select
Clock select
Reset pin
Clamp pin
For testing purposes
For testing purposes
For testing purposes
(DC offset: -0.26)
WAFP for DOS/V V1.3 *** copyright 1993, 94 by TOSHIBA [AVL] ***
[amp: dB]
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
-60
-65
-70
-75
-5
Function
5
0
0
2M
4M
CONV. TIM
6M
6
Sets relationship between input H frequency and HPLL oscillation
frequency.
Also switches between internal oscillation frequency and external
clock input. When selecting clock using I
CKSEL to all L.
H for normal operation, L for reset
Input for ADC clamp signal. Polarity can be changed using I
bus register. By default, clamp is applied by H.
Switches between external input / internal generation of clamp
signal according to I
Set to L.
TES1 and TES0 determine 2 least significant bits of I
control slave address (details are given later).
8M
10M
May 10 1999
[freq: Hz]
12M
2
C Bus Register setting.
Notes
2
C bus register, set
TC90A58F
2002-02-06
2
C bus
2
C