1
Video ICs
SECAM chroma signal processor for
VHS VCRs
BA7207AS / BA7207AK
The BA7207AS and BA7207AK are LSI components that incorporate the contain circuitry required for SECAM chro-
ma signal processing. The ICs have both recording and playback systems and each includes a bell filter, a band-
pass filter, a limiter amplifier, a multiply-by-four circuit, a divide-by-four circuit, and a sync-gate circuit.
·
Applications
SECAM and VHS format video cassette recorders and
camcorders
·
Features
1) All filters required for SECAM chroma signal pro-
cessing are provided.
2) Built-in chroma killer circuit.
3) Built-in switch circuit for selecting PAL chroma or
SECAM chroma for the PB / REC system output.
·
Absolute maximum ratings (Ta = 25°C)
·
Recommended operating conditions (Ta = 25°C)
Parameter
Symbol
Limits
Unit
Power supply voltage
Power dissipation
Storage temperature
V
CC
7
V
BA7207AS
BA7207AK
BA7207AS
BA7207AK
mW
Pd
Topr
°
C
Tstg
°
C
1400 (SDIP32)
1
25 ~ + 75
850 (QFP44)
2
25 ~ + 65
55 ~ + 125
1 Reduced by 14mW for each increase in Ta of 1
°
C over 25
°
C .
2 When mounted on a 70mm
×
70mm, t = 1.6mm glass epoxy board, reduced by 8.5W for each
increase in Ta of 1
°
C over 25
°
C.
Operating temperature
Parameter
Symbol
Min.
Typ.
Max.
Unit
Operating power supply voltage
V
CC
4.5
5.0
5.5
V
3
Video ICs
BA7207AS / BA7207AK
·
Pin descriptions
Pin name
1 (40) RECIN
2 (42)
MUL
3 (43) FADJ1
4 (44) FADJ2
5 (1)
GND1
6 (2) AMPOUT
7 (3)
GND
8 (5) SCMPIN
9 (7)
DET
10 (9)
VCO
11 (10) PBOUT
12 (11) SGADJ
13 (12)
SGC
Pin No.
Function
Recording system input.
Input the REC system chroma signal.
PB sync gate output.
Test pin. Outputs the chroma signal after it is
multiplied by four and passed through the sync
gate. Normally connected to V
CC
to prevent
interference.
Filter fo adjustment pin 1.
Used to adjust fo for the equalizer, 1.1MHz BPF
and 2.2MHz BPF. Connect a resistor and variable
resistor from this pin to GND.
Filter fo adjustment pin 2.
Used to adjust fo for the bell filter, 4.3MHz BPF-A
and 4.3MHz BPF-B. Connect a resistor and
variable resistor from this pin to GND.
Ground.
PB system preamplifier output.
Connect to GND via a variable resistor to adjust
the level, and input to pin 8.
Ground.
PB system output amplifier input.
Input the level-adjusted PB system SECAM
chroma signal.
Phase comparator output.
Connect to GND via a RC LPF to obtain the error
voltage.
VCO oscillator frequency control pin.
The error voltage is input via a resistor.
Connected to GND via free-running frequency
setting resistor.
PB system output.
Outputs the PB system chroma signal.
Fine adjustment for the sync gate phase.
The voltage from a resistor divider is used for fine
adjustment of the gate phase of the sync gate.
Normally open.
Sync gate timing output.
Test pin. Outputs the REC sync gate timing.
Normally open.
14 (13) PALPIN
15 (14)
DIV
16
SYNCIN
PAL PB system input.
Input chroma signal for the PAL PB system.
Divide-by-four divider output.
Test pin. Outputs the chroma signal after it has
been divided by four. Normally connected to V
CC
to prevent interference.
Delayed sync signal input.
Input the synchronously-separated composite
17 (18)
BWL
18 (20)
PBIN
19 (21) RECH
20 (22) CREF3
21 (23)
CTL
22 (24)
LAO
23 (25)
24 (27)
LAIN
25 (29) CREF1
26 (31) ABELO
27 (32) CREF2
BA7207AK pin numbers are given in brackets.
Pin name
Pin No.
Function
V
CC
Chroma killer mode setting . "L" sets the IC in
chroma killer mode.
PB system input .
Input chroma signal for the PB system.
REC / PB mode switch.
Set to open or "H" for REC mode, "L" for PB
mode.
Bias terminal for the limiter amplifier before
×
2.
Connect to GND via a capacitor.
SECAM / PAL output switch.
Selects the signal output for the REC / PB
terminal. Set to open or "H" for SECAM output
mode, "L" for PAL mode.
Limiter amplifier output.
Test pin. Outputs the amplitude-limited chroma
signal. Normally connected to V
CC
to prevent
interference.
Power supply.
Limiter amplifier input.
Input the de-emphasised chroma signal.
Limiter amplifier bias pin 1.
Connect to GND via a capacitor.
REC BELL output. When in REC mode,
de-emphasised chroma signal is output via REC
BELL. When in PB mode, the PB system chroma
signal is output after being multiplied by four.
Limiter amplifier bias pin 2.
Connect to GND via a capacitor.
28 (33) RECOUT
29 (34) TRAP
30 (35) PALRIN
REC system output.
REC system chroma signal output.
TRAP connection.
Connect TRAP that rejects spurious signal
component after
×
2 multiplication.
PAL REC system input.
PAL REC system chroma signal input.
31 (36) VREG
32 (38)
×
40
Regulated voltage output.
Output for the regulated 2.5V reference voltage
used for internal biasing. Connect to GND via a
bypass capacitor.
×
4 multiply output.
Test pin. Outputs the chroma signal after it is
multiplied by four. Normally connected to V
CC
to
prevent interference.
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