Datasheet BA7745FS Datasheet (ROHM)

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 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
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 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.

2

Video ICs BA7745FS

•

Block diagram

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16151413121110987654321

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

PREPRE

SW

EP

CH2 CH1

CH2CH1

RR

BF

N.C.

FE OSC

FE

CTRL

N.C.

VCA

REC

•

Absolute maximum ratings (Ta = 25°C)

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 = 25°C)

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 = 25°C, V

CC = 5V, and f = 1.7MHz)

Parameter Symbol Min. Typ. Max. Unit Conditions

17pin: H

Iq

(REC)

—6690mA

I

OAR

44.7 48.2 51.7

15pin 93.0dBµIN, 19pin OUT

∆I

OAR

10 13 — dB

∆AGC < 0.8dB, 19pin OUT

CMD04— – 50 – 43 dB

15pin MIXIN (∗), 19pin OUT (0.4MHz – 1.3MHz)

CMD09— – 55 – 40 dB

15pin MIXIN (∗), 19pin OUT (0.9MHz – 1.3MHz)

2HD26— – 47 – 40 dB

15pin MIXIN (∗), 19pin OUT (2.6MHz – 1.3MHz)

CMD30— – 42 – 35 dB

15pin MIXIN (∗), 19pin OUT (3.0MHz – 1.3MHz)

2HD34— – 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 (89.0dBµ) + 1.7MHz (97.0dBµ) (MIX)

15pin 93.0dBµIN, 14pin: “H”

15pin 93.0dBµIN, 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 = 25°C, VCC = 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, 20.5dBµIN, 10pin OUT, 8pin: “H”
25pin, 20.5dBµIN, 10pin OUT, 8pin: “L”

23pin 31.0dBµ, 25pin 0 IN,

23pin 0, 25pin 31.0dBµIN,

23pin 20.5dBµIN, 8pin: “H”
f = 2.2MHz / 1.0MHz, ∆10pin OUT
25pin 20.5dBµIN, 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 µV

rms

V

NP2

— 0.4 1.0 µV

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

—510Ω

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, 20.5dBµIN, ∆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: 0.01µF + 10Ω at GND

Pin 8: “H”, pin 10 OUT.
Input conversion for pin 25: 0.01µF + 10Ω 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 20.5dBµIN, 9pin: “H”, 10pin OUT

•

Design reference values

Flying erase system (unless otherwise noted, Ta = 25°C, 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

υ

32 — 2.8 — VP-P 32pin OUT

V

5H 4.0 — VCC V

0 — 0.5 VV

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

0.01µ

20k

5V

390

0.01

µ

100µ

100µ

AGC

P / R

P

PB / REC

PREPRE

SW

EP

CH2 CH1

CH2CH1

RR

BF

N.C.

FE OSC

FE

CTRL

N.C.

2.2k

VCA

0.1

µ

68k

12

680

220p

0.1µ

0.01µ0.01µ

0.1µ

12µ12µ

100µ

11V

BF

100µ

470

0.01µ

560

1k

560

0.22µ

0.1µ220k

1010

100p100p

1k

12pin SHORT

FE OUT

PRE IN CH1

PRE IN CH2

CURRENT

SENSE

PB / REC

CTRL

0.01µ

REC

REC MIX IN

OVERREC

CTR L

RECMUTE

CTRL

1.8k

PRE OUT

EP / SP CTRL

HSWPIN

FE ON / OFF

68p

22k

4.7µ

68p

0.01µ

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16151413121110987654321

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—

60.0mAP-P

48.2mAP-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

17181920212223242526272829303132

120p120p

1.5k1.5k

10

FE HEAD

10

8.2k8.2k

16151413

0.01µ

20k

5V

390

0.01µ

100µ

100µ

121110987654321

AGC

P / R

P

PB / REC

PREPRE

SW

EP

CH2 CH1

CH2CH1

RR

BF

N.C.

FE OSC

FE

CTRL

N.C.

2.2k

VCA

0.1µ

68k

12

680

220p

0.1µ

0.01µ0.01µ

0.1µ

100µ

11V

100µ

470

0.01µ

560

560

0.22µ

0.1µ220k

560560

100p

AUDIO HEAD

100p

12pin SHORT

CURRENT

SENSE

PB / REC

CTRL

0.01µ

REC

REC MIX IN

OVERREC

CTR L

RECMUTE

CTRL

1.8k

PRE OUT

EP / SP CTRL

HSWPIN

FE ON / OFF

68p

22k

4.7µ

68p0.01µ

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