AK4254 Datasheet, PDF (19/22 Pages) Asahi Kasei Microsystems – Capacitor-less Video Amp with 7:2 Video Switch

ASAHI KASEI
[AK4254]
Video out
Power Supply 3V
Video in
1 CVDD1
+
1u
2 CP1
3 CN1
1u ⁺
75
4 CVSS1
5 CVEE1
6 VOUT1
+
10u
7
0.1u
8
AVDD
AVSS
9 TEST
10 P/S
0.1u
11 VIN1
0.1u
12 VIN2
0.1u
13 VIN3
0.1u
14 VIN4
0.1u
15 VIN5
CVDD2 30
CP2 29
CN2 28
CVSS2 27
CVEE2 26
AK4254 ^{VOUT2 25}
PDN 24
I2C 23
SDA 22
SCL 21
CSN 20
CAD1 19
CAD0 18
VIN7 17
VIN6 16
+
1u
+ _1u
75
0.1u
0.1u
Video out
DSP or μP
Video in
Figure 17. Typical Connection Diagram (Serial Control Mode: I²C Bus mode)
1. Grounding and Power Supply Decoupling
The AK4254 requires careful attention to power supply and grounding arrangements. AVDD, CVDD1 and CVDD2 are
usually supplied from the system’s analog supply. AVSS, CVSS1 and CVSS2 of the AK4254 should be connected to the
analog ground plane. System analog ground and digital ground should be connected together near to where the supplies
are brought onto the printed circuit board. Decoupling capacitors should be as near to the AK4254 as possible, with the
small value ceramic capacitor being the nearest.
2. Analog Inputs
Usually the input signal is AC coupled using 0.1uF capacitor (Figure 15, Figure 16, Figure 17).
3. The notes for drawing the board
Analog input and output pins should be as short as possible in order to avoid unwanted coupling into the AK4254. The
unused pins should be open.
4. Video Output
The AK4254 are on-chip 2ch video amp for drive 150Ω resistance. The gain of each amp is +6dB (typ) (Figure 1).
MS0586-E-01
- 19 -
2007/08