1
Video ICs
VCR Hi-Fi audio signal REC / PB
amplifier with flying-erase oscillator
BA7745FS
The BA7745FS has the recording and playback amplifiers required for Hi-Fi VCR signal processing, and also con-
tains a flying-erase oscillator. The recording system uses a constant-current amplifeir with AGC to eliminate the need
to adjust the recording current, and ensure stable operation as the head wears. The IC also features REC MUTE and
OVER REC functions .
The playback system has a high-gain preamplifier, a low-offset head switch, a VCA and an EP-gain amplifier. The
flying-erase oscillator has low 2nd and 3rd harmonic distortion, and when connected to an external driver large out-
put current can be obtained.
A H / L control system eliminates the need for special power supplies for the recording and playback systems. The
IC has low power consumption, and comes in a compact 32-pin SSOP-P package that requires little area on the
PCB. It will improve the reliability and performance of your designs while reducing external component requirements.
Applications
VCRs
Features
The low-noise playback amplifier has a total gain of
83dB (Typ.). Designed for VHS-bandoperation with
low external parts count. It has two built-in circuits for
Hi-Fi VCR operation.
2) The circuit has been designed to suppress head-
switching noise.
3) Built-in EP / SP gain switching function that boosts
the playback gain by 5dB.
4) Built-in VCA for easy playback output adjustment.
5) High-output recording amplifier for audio FM record-
ing.
6) Constant-current drive provides stable recording
characteristics when the load (head impedance) is
fluctuating.
7) Built-in recording level AGC eliminates the need to
adjust recording current.
8) Built-in low-pass filter limits the input bandwidth of
the recording amplifier.
9) Built-in OVER REC recording current amplifier
function and REC MUTE function that stops record-
ing output.
10) Built-in high-frequency oscillator for use with flying
erase function.
11) Record / playback switching can be done directly
via the system controller, and consumes litlle
power.
12) Possible to construct a high-performance audio
system by pairing this chip with a Hi-Fi-audio signal
processing IC.
2
Video ICs
BA7745FS
Block diagram
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
REC / PB CTRL
REC AGC FILTER
REC CURRENT SENSE
REC OUT
MAIN GND
PRE AC FB CH1
PRE AC FB CH2
PRE IN CH1
PRE GND
PRE IN CH2
REC + B CH2
V
CC
REC + B
N.C.
FE V
CC
FE OUT
REC + B CH1
REC NF
REC MIX IN
OVER REC CTRL
REC MUTE CTRL
V
CC
VCA CTRL
N.C.
PRE OUT
EP / SP CTRL
HSWPIN
FE LEVEL
FE3
FE2
FE1
FE GND
FE CTRL
AGC
P / R
P
PB / REC
PRE
PRE
SW
EP
CH2
CH1
CH2
CH1
R
R
BF
N.C.
FE OSC
FE
CTRL
N.C.
VCA
REC
Absolute maximum ratings (Ta = 25C)
Parameter
Symbol
Limits
Unit
V
CC
7.0
V
12.5
Pd
1000
mW
Topr
10 ~ + 70
C
Tstg
55 ~ + 125
C
PB / REC system
FE system
Power supply voltage
Power dissipation
Operating temperature
Storage temperature
When mounted on a 90mm
50mm
1.6mm glass epoxy board, reduced by 10mW for
each increase in Ta of 1
C over 25
C.
3
Video ICs
BA7745FS
Recommended operating conditions (Ta = 25C)
Parameter
Symbol
Min.
Typ. Max.
Unit
4.5
5.0
5.5
V
10.5
11.0
11.5
V
V
CCS
Recommended
operating voltage
PB / REC system
FE system
Electrical characteristics
Recording system (unless otherwise noted, Ta = 25C, V
CC
= 5V, and f = 1.7MHz)
Parameter
Symbol
Min.
Typ.
Max.
Unit
Conditions
17pin: H
Iq
(REC)
--
66
90
mA
I
OAR
44.7
48.2
51.7
15pin 93.0dB
IN, 19pin OUT
I
OAR
10
13
--
dB
AGC < 0.8dB, 19pin OUT
CMD
04
--
50
43
dB
15pin MIXIN (
), 19pin OUT (0.4MHz 1.3MHz)
CMD
09
--
55
40
dB
15pin MIXIN (
), 19pin OUT (0.9MHz 1.3MHz)
2HD
26
--
47
40
dB
15pin MIXIN (
), 19pin OUT (2.6MHz 1.3MHz)
CMD
30
--
42
35
dB
15pin MIXIN (
), 19pin OUT (3.0MHz 1.3MHz)
2HD
34
--
45
40
dB
15pin MIXIN (
), 19pin OUT (3.4MHz 1.7MHz)
V
14L
0.0
--
2.2
V
3.5
--
V
I
OR.OV
+ 1.4
+ 1.9
+ 2.4
dB
V
13L
0.0
--
2.2
V
V
13H
3.5
--
V
I
OR.MU
--
45
40
dB
V
CC
V
CC
mA
P-P
V
14H
f = 1.3MHz (89.0dB
) + 1.7MHz (97.0dB
) (MIX)
15pin 93.0dB
IN, 14pin: "H"
15pin 93.0dB
IN, 13pin: "H"
When 14pin DC, NORMAL REC
When 14pin DC, OVER REC
When 13pin DC, MUTE OFF
When 13pin DC, MUTE ON
No signal, pin 12 + pin 29, inflow current
Recording mode
Quiescent current
Output current AGC level
Output current AGC range
Cross modulation distortion 0.4MHz component
Cross modulation distortion 0.9MHz component
2nd-harmonic distortion 2.6MHz component
Cross modulation distortion 3.0MHz component
2nd-harmonic distortion 3.4MHz component
OVER REC holding voltage
OVER REC holding voltage
Current emphasis OVER
REC MUTE holding voltage
REC MUTE holding voltage
Mute attenuation
4
Video ICs
BA7745FS
Playback system (unless otherwise noted, Ta = 25C, V
CC
= 5V, and f = 1.5MHz)
Parameter
Symbol
Min.
Typ.
Max.
Unit
Conditions
Iq
(PB)
--
19.0
31.0
mA
G
VP1
80
83
86
dB
G
VP2
80
83
86
dB
G
VP
2.0
0
+ 2.0
dB
CT
1
2
--
40
35
dB
CT
2
1
--
40
35
dB
f
P1
0
2.4
5
dB
f
P2
0
2.4
5
dB
17pin: "L" 11pin: 2.0V
23pin, 20.5dB
IN, 10pin OUT, 8pin: "H"
25pin, 20.5dB
IN, 10pin OUT, 8pin: "L"
23pin 31.0dB
, 25pin 0 IN,
23pin 0, 25pin 31.0dB
IN,
23pin 20.5dB
IN, 8pin: "H"
f = 2.2MHz / 1.0MHz,
10pin OUT
25pin 20.5dB
IN, 8pin: "L"
f = 2.2MHz / 1.0MHz,
10pin OUT
G
VCA
--
40
30
dB
+
G
VCA
+ 4
+ 6
--
dB
V
OMP
2.0
2.6
--
V
P-P
V
NP1
--
0.4
1.0
V
rms
V
NP2
--
0.4
1.0
V
rms
V
HS2
0.0
--
2.2
V
V
HS1
2.8
--
V
CC
V
V
ODC
20
0
+ 20
mV
V
17L
0.0
--
1.0
V
V
17H
3.5
--
V
CC
V
R
SWP
--
5
10
V
9L
0.0
--
--
2.2
V
V
9H
3.5
V
CC
V
G
VP. EP
4.0
5.0
6.0
dB
8pin: "H"
"L",
10pin OUT
8pin: "H"
"L",
10pin OUT
11pin 2.0V
0.8V,
10pin OUT
11pin 2.0V
3.3V,
10pin OUT
23pin, 25pin, 20.5dB
IN,
10pin OUT
Playback mode
Supply current
Voltage gain CH1
Voltage gain CH2
Voltage gain differential
CH1 to CH2 crosstalk
CH2 to CH1 crosstalk
CH1 frequency characteristic
CH2 frequency characteristic
Gain adjustment headroom
Gain adjustment headroom
Maximum output voltage
CH1 input conversion noise
CH2 input conversion noise
Head switch voltage
Head switch voltage
Output DC offset
PB holding voltage
REC holding voltage
Head switch-on resistance
SP holding voltage
EP holding voltage
Gain emphasis EP
Inflow current to pin 12 when no signal.
Pin 23 and 25 IN, pin 10 OUT 3rd-harmonic distortion, when -30dB.
Input conversion for pin 23: 0.01
F + 10
at GND
Pin 8: "H", pin 10 OUT.
Input conversion for pin 25: 0.01
F + 10
at GND
Pin 8: "L", pin 10 OUT.
Pin 8 DC when CH2 operating
Pin 8 DC when CH1 operating
23, 25pin 0 IN, 8pin: "H"
"L",
10pin OUT
Pin 17 DC for PB mode
Pin 17 DC for REC mode
Pin 20 ON resistance
Pin 9 DC for SP mode
Pin 9 DC for EP mode
23, 25pin 20.5dB
IN, 9pin: "H", 10pin OUT
Design reference values
Flying erase system (unless otherwise noted, Ta = 25C, V
CC
= 11.0V)
Parameter
Symbol
Min.
Typ.
Max.
Unit
Conditions
5pin: "H"
Iq
(FE)
--
12.0
--
mA
V
2
--
5.5
--
V
2pin DC
V
3
--
5.5
--
V
3pin DC
V
6
--
1.0
--
V
6pin DC
V
32
--
4.3
--
V
32pin DC
f
32
8
--
13
MHz
32pin OUT
32
--
2.8
--
V
P-P
32pin OUT
V
5H
4.0
--
V
CC
V
0
--
0.5
V
V
5L
5pin DC, When FE ON
5pin DC, When FE OFF
Flying erase mode
Supply current
Pin 2 voltage
Pin 3 voltage
Pin 6 voltage
Pin 32 voltage
Oscillator frequency range
Output amplitude range
FE ON holding voltage
FE OFF holding voltage
The values given above are design values, they are not ratings and are not guaranteed.
Pin 31 inflow current
5
Video ICs
BA7745FS
Control mode tables
(1) REC / PB control
Switch between REC and PB using pin 17.
Control pin
Mode
REC / PB
H
REC
ON
OFF
ON
OFF
L
PB
OFF
ON
OFF
ON
REC AMP PRE AMP REC + B SW HEAD SW (P)
Function
0.01
20k
5V
390
0.01
100
100
AGC
P / R
P
PB / REC
PRE
PRE
SW
EP
CH2
CH1
CH2
CH1
R
R
BF
N.C.
FE OSC
FE
CTRL
N.C.
2.2k
VCA
0.1
68k
12
680
220p
0.1
0.01
0.01
0.1
12
12
100
11V
BF
100
470
0.01
560
1k
560
0.22
0.1
220k
10
10
100p
100p
1k
12pin SHORT
FE OUT
PRE IN CH1
PRE IN CH2
CURRENT
SENSE
PB / REC
CTRL
0.01
REC
REC MIX IN
OVERREC
CTR L
RECMUTE
CTRL
1.8k
PRE OUT
EP / SP CTRL
HSWPIN
FE ON / OFF
68p
22k
4.7
68p
0.01
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Fig. 1
Measurement circuit
6
Video ICs
BA7745FS
(2) OVER REC control
Control for OVER REC (current emphasis) is done using pin 14.
When in OVER REC mode, the gain setting is recording amplifier AGC level + 1.9dB.
H
L
--
60.0mA
P-P
48.2mA
P-P
OVER REC
OVER REC
Mode
Function
REC AGE Level
Control pin
(4) EP / SP control
EP / SP control during playback is done using pin 9. When EP is selected, the gain of the playback amplifier is
increased by 5dB over its normal setting.
EP / SP
H
EP
Typ. + 5dB
L
SP
Typ.
Mode
Function
PRE AMP gain
Control pin
(3) REC MUTE control
Control for REC MUTE when recording is done using pin 13.
REC
MUTE
H
REC
MUTE
OFF
L
--
ON
REC AMP
Mode
Control pin
Function
7
Video ICs
BA7745FS
Application example
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
120p
120p
1.5k
1.5k
10
FE HEAD
10
8.2k
8.2k
16
15
14
13
0.01
20k
5V
390
0.01
100
100
12
11
10
9
8
7
6
5
4
3
2
1
AGC
P / R
P
PB / REC
PRE
PRE
SW
EP
CH2
CH1
CH2
CH1
R
R
BF
N.C.
FE OSC
FE
CTRL
N.C.
2.2k
VCA
0.1
68k
12
680
220p
0.1
0.01
0.01
0.1
100
11V
100
470
0.01
560
560
0.22
0.1
220k
560
560
100p
AUDIO HEAD
100p
12pin SHORT
CURRENT
SENSE
PB / REC
CTRL
0.01
REC
REC MIX IN
OVERREC
CTR L
RECMUTE
CTRL
1.8k
PRE OUT
EP / SP CTRL
HSWPIN
FE ON / OFF
68p
22k
4.7
68p
0.01
11V
Fig. 2
8
Video ICs
BA7745FS
External dimensions (Units: mm)
SSOP-P32
0.25
0.1
0.8
13.6
0.2
17
16
0.36
0.1
32
1
0.11
1.9
0.1
5.4
0.2
7.8
0.3
0.3Min.
0.15
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