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.
•
ApplicationsVHS format video cassette recorders and
SECAM and
camcorders
•
Features required for SECAM chroma signal pro-
1) All filters
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)
Parameter
Power supply voltage
Power dissipation
Operating temperature
Storage temperature
BA7207AS
BA7207AK
BA7207AS
BA7207AK
Symbol
V
CC
Pd
Limits
7
1400 (SDIP32)
∗
1
850 (QFP44)
∗
2
– 25 ~ + 75
– 25 ~ + 65
– 55 ~ + 125
Unit
V
mW
°C
°C
Topr
Tstg
∗
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.
•
Recommended operating conditions (Ta = 25°C)
Parameter
Operating power supply voltage
Symbol
V
CC
Min.
4.5
Typ.
5.0
Max.
5.5
Unit
V
1
Video ICs
BA7207AS / BA7207AK
•
Pin descriptions
Pin No. Pin name
1 (40)
RECIN
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.
Pin No. Pin name
17 (18)
18 (20)
BWL
PBIN
Function
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.
2 (42)
MUL
19 (21) RECH
3 (43)
FADJ1
20 (22) CREF3
Connect to GND via a capacitor.
4 (44)
FADJ2
21 (23)
CTL
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.
5 (1)
GND1
22 (24)
LAO
6 (2) AMPOUT
7 (3)
8 (5)
GND
23 (25)
24 (27)
V
CC
LAIN
SCMPIN
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.
25 (29) CREF1
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.
9 (7)
DET
26 (31) ABELO
10 (9)
VCO
27 (32) CREF2
Connect to GND via a capacitor.
28 (33) RECOUT
REC system chroma signal output.
29 (34)
TRAP
TRAP connection.
Connect TRAP that rejects spurious signal
component after
×
2 multiplication.
PAL REC system input.
REC system output.
11 (10) PBOUT
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.
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.
12 (11) SGADJ
30 (35) PALRIN
PAL REC system chroma signal input.
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.
BA7207AK pin numbers are given in brackets.
13 (12)
SGC
31 (36) VREG
14 (13) PALPIN
15 (14)
DIV
32 (38)
×
40
16
SYNCIN
Input the synchronously-separated composite
3
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