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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 contains 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 output 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 playback amplifier has a total gain of The low-noise
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 headswitching 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 recording. 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 recording 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.
1
Video ICs
BA7745FS
*Block diagram
P/R 17 16 AGC REC 15 14 13 P 12 PB / REC 11 VCA 10 9 N.C. 8 CH2 CH2 7 6 FE CTRL 5 FE OSC BF 4 N.C. 3 2 1 CH1 EP SW PRE CH1 PRE R R REC / PB CTRL REC NF 18 REC AGC FILTER REC MIX IN
19
REC CURRENT SENSE
OVER REC CTRL
20
REC OUT
REC MUTE CTRL
21
MAIN GND
VCC
22
PRE AC - FB CH1
VCA CTRL
23
PRE IN CH1
PRE OUT
24
PRE GND
EP / SP CTRL
25
PRE IN CH2
HSWPIN
26
PRE AC - FB CH2
N.C.
27
REC + B CH2
FE LEVEL
REC + B CH1
28
FE CTRL
VCC REC + B
29
FE3
N.C.
30
FE2
FE VCC
31
FE1
FE OUT
32
FE GND
*Absolute maximum ratings (Ta = 25C)
Parameter Power supply voltage Power dissipation Operating temperature Storage temperature Symbol VCC Pd Topr Tstg Limits PB / REC system FE system 1000 - 10 ~ + 70 - 55 ~ + 125 7.0 12.5 Unit V mW C C
When mounted on a 90mm x 50mm x 1.6mm glass epoxy board, reduced by 10mW for each increase in Ta of 1C over 25C.
2
Video ICs
BA7745FS
*Recommended operating conditions (Ta = 25C)
Parameter Recommended operating voltage PB / REC system FE system Symbol VCCS Min. Typ. Max. 4.5 5.0 5.5 Unit V V 10.5 11.0 11.5
characteristics *Electricalsystem (unless otherwise noted, Ta = 25C, VCC = 5V, and f = 1.7MHz) Recording
Parameter 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 Symbol Iq (REC) IOAR IOAR CMD04 CMD09 2HD26 CMD30 2HD34 V14L V14H IOR.OV V13L V13H IOR.MU Min. Typ. Max. 90 51.7 -- - 43 - 40 - 40 - 35 - 40 2.2 VCC + 2.4 2.2 VCC - 40 Unit mA mAP-P dB dB dB dB dB dB V V dB V V dB Conditions 17pin: H No signal, pin 12 + pin 29, inflow current 15pin 93.0dBIN, 19pin OUT AGC < 0.8dB, 19pin OUT 15pin MIXIN (), 19pin OUT (0.4MHz - 1.3MHz) 15pin MIXIN (), 19pin OUT (0.9MHz - 1.3MHz) 15pin MIXIN (), 19pin OUT (2.6MHz - 1.3MHz) 15pin MIXIN (), 19pin OUT (3.0MHz - 1.3MHz) 15pin MIXIN (), 19pin OUT (3.4MHz - 1.7MHz) When 14pin DC, NORMAL REC When 14pin DC, OVER REC 15pin 93.0dBIN, 14pin: "H" When 13pin DC, MUTE OFF When 13pin DC, MUTE ON 15pin 93.0dBIN, 13pin: "H"
-- 66 44.7 48.2 10 13 -- - 50 -- - 55 -- - 47 -- - 42 -- - 45 0.0 -- 3.5 -- + 1.4 + 1.9 0.0 -- 3.5 -- -- - 45
f = 1.3MHz (89.0dB) + 1.7MHz (97.0dB) (MIX)
3
Video ICs
Playback system (unless otherwise noted, Ta = 25C, VCC = 5V, and f = 1.5MHz)
Parameter 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 Symbol Iq (PB) GVP1 GVP2 GVP CT12 CT21 fP1 fP2 - GVCA + GVCA VOMP VNP1 VNP2 VHS2 VHS1 VODC V17L V17H RSWP V9L V9H GVP. EP Min. -- 80 80 - 2.0 -- -- 0 0 -- +4 2.0 -- -- 0.0 2.8 - 20 0.0 3.5 -- 0.0 3.5 4.0 Typ. Max. Unit mA dB dB dB dB dB dB dB dB dB VP-P Vrms Vrms V V mV V V V V dB
BA7745FS
19.0 31.0 83 86 83 86 0 + 2.0 - 40 - 40 - 2.4 - 2.4 - 40 +6 2.6 0.4 0.4 -- -- 0 -- -- 5 -- -- 5.0 - 35 - 35 -5 -5 - 30 -- -- 1.0 1.0 2.2 VCC + 20 1.0 VCC 10 2.2 VCC 6.0
Conditions 17pin: "L" 11pin: 2.0V Inflow current to pin 12 when no signal. 23pin, 20.5dBIN, 10pin OUT, 8pin: "H" 25pin, 20.5dBIN, 10pin OUT, 8pin: "L" 23pin, 25pin, 20.5dBIN, 10pin OUT 23pin 31.0dB, 25pin 0 IN, 8pin: "H" "L", 10pin OUT 23pin 0, 25pin 31.0dBIN, 8pin: "H" "L", 10pin OUT 23pin 20.5dBIN, 8pin: "H" f = 2.2MHz / 1.0MHz, 10pin OUT 25pin 20.5dBIN, 8pin: "L" f = 2.2MHz / 1.0MHz, 10pin OUT 11pin 2.0V3.3V, 10pin OUT 11pin 2.0V0.8V, 10pin OUT Pin 23 and 25 IN, pin 10 OUT 3rd-harmonic distortion, when -30dB. Input conversion for pin 23: 0.01F + 10 at GND Pin 8: "H", pin 10 OUT. Input conversion for pin 25: 0.01F + 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 20.5dBIN, 9pin: "H", 10pin OUT
*Design reference values otherwise noted, Ta = 25C, VCC = 11.0V) Flying erase system (unless
Parameter 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 Iq (FE) V2 V3 V6 V32 f32 32 V5H V5L -- -- -- -- -- 8 -- 4.0 0 12.0 5.5 5.5 1.0 4.3 -- 2.8 -- -- -- -- -- -- -- 13 -- VCC 0.5 mA V V V V MHz VP-P V V Symbol Min. Typ. Max. Unit 5pin: "H" Pin 31 inflow current 2pin DC 3pin DC 6pin DC 32pin DC 32pin OUT 32pin OUT 5pin DC, When FE ON 5pin DC, When FE OFF Conditions
The values given above are design values, they are not ratings and are not guaranteed. 4
Video ICs
BA7745FS
0.22
*Measurement circuit
68k 220k 0.1 PB / REC CTRL 12 CURRENT SENSE
P/R
17
16
0.01
0.1
AGC
REC
REC MIX IN
18
15
220p
680
OVERREC CTR L RECMUTE CTRL 5V 0.01 PRE OUT EP / SP CTRL HSWPIN FE ON / OFF 22k
19
20
13
14
0.01
0.1 22 21
P
PB / REC
560
12
PRE
VCA
0.01 0.01
100p
SW
EP
24
100p
10
PRE IN CH2 1k
PRE
25
0.1
560
CH2
N.C.
26
12
CH2
27
R
FE CTRL
6
7
8
9
CH1
28
12
12pin SHORT
29
R
4
5
FE OSC
30 N.C.
68p
2.2k
1.8k
PRE IN CH1
10
23
10
1k
CH1
100
0.01
100
11V
31
2
BF
FE OUT
32
470
Fig. 1
*Control/ mode tables (1) REC PB control
Switch between REC and PB using pin 17.
Control pin REC / PB H L Mode REC PB Function REC AMP PRE AMP REC + B SW HEAD SW (P) ON OFF OFF ON ON OFF OFF ON
1
0.01
68p
4.7
BF
3
390 20k
11
100
100
5
Video ICs
(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.
Control pin OVER REC H L Mode OVER REC -- Function REC AGE Level 60.0mAP-P 48.2mAP-P
BA7745FS
(3) REC MUTE control Control for REC MUTE when recording is done using pin 13.
Control pin REC MUTE H L Mode REC MUTE
--
Function REC AMP OFF ON
(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.
Control pin EP / SP H L Mode EP SP Function PRE AMP gain Typ. + 5dB Typ.
6
Video ICs
FE HEAD CURRENT SENSE 11V AUDIO HEAD
*Application example
PB / REC CTRL
10 100 11V 100 100p 560 560 0.01 0.1 25 24 23 22 21 20 19 0.01 0.1 32 N.C. R PRE CH1 BF SW PB / REC EP CH2 CH2 PRE CH1 P R 31 30 29 28 27 26 560 220p 560 680 12 100p
10
1.5k 120p 0.01 470 120p
8.2k 1.5k
8.2k
220k 0.1 68k
12pin SHORT
0.22 18 17
P/R
AGC
Fig. 2
FE OSC FE CTRL N.C. 1 0.01 68p 4.7 22k 68p 2 3 4 5 2.2k 6 7 8 HSWPIN FE ON / OFF
VCA REC
9 1.8k
10
11
12
13
14
15
16 0.01 0.01 390 20k 100 100 0.01 5V PRE OUT OVERREC CTR L RECMUTE CTRL EP / SP CTRL REC MIX IN 0.1
BA7745FS
7
Video ICs
BA7745FS
*External dimensions (Units: mm)
13.6 0.2 32 7.8 0.3 5.4 0.2 17
1 1.9 0.1
16
0.11
0.8
0.36 0.1
0.3Min. 0.15
SSOP-P32
8
0.25 0.1

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