Video ICs

2-channel PRE / REC amplifier with
auto-tracking interface

BA7181FS

The BA7181FS is a PRE / REC amplifier developed for use in video cassette recorders. It has been designed for use

in two-head decks and features built-in FB damping, two preamplifiers, a chroma output amplifier, an FM output

amplifier (with AGC), an envelope detector, a constant-current BTL-drive REC amplifier (with AGC)and built-in chan-

nel and REC / PB switches on a single monolithic IC.

Applications

VCRs

Features

1) The playback amplifier has a total gain of 57dB

(Typ.), and has a low-noise preamplifier. Designed

for VHS-band operation with low external parts

count. The IC has two circuits for two-head VCR

applications.

2) Two playback output systems (through output and

AGC output). The AGC output level is 300mV

P-P

(Typ.);

suitable for FM brightness signal output.

3) Auto-tracking interface is provided for automated

tracking adjustment. The detector characteristic is

linear, and the sensitivity can be adjusted using

external components.

4) The recording amplifier uses constant-current BLT

drive that handles load variations (i.e. head imped-

ance)well, and gives stable recording characteris-

tics. A single circuit is provided for two-head VCR

use.

5) Built-in recording level AGC means adjustment of

FM recording current is not necessary.

6) Head switches for two-channel PRE / REC system

provided.

7) Operates off a single 5V power supply, with low

power dissipation.

Absolute maximum ratings (Ta = 25°C)

Parameter

Symbol

Limits

Unit

Applied voltage

Power dissipation

Operating temperature

Storage temperature

7.0

937.5

Topr

Tstg

When mounted on a 90mm

50mm, t = 1.6mm glass epoxy board.

Reduced by 7.5mW for each increase in Ta of 1

C over 25

20 ~ + 65

55 ~ + 150

Recommended operating (Ta = 25°C)

Parameter

Symbol

Min.

Typ.

Max.

Unit

Conditions

Playback / recording (voltage range)

4.5

5.0

5.5

11pin

Not designed for radiation resistance.

Video ICs

BA7181FS

Block diagram

123

456789

PRE

DET

AGC

PRE

LOGIC

ENVE

PEAK

MUTE

REC

AGC

HPF

DET

(REC - OUT 1)

(REC - OUT 2)

DFF IN

DET FILTER

REC DCFB

PRE IN 1

GND 1

PRE IN 2

PB / EE / REC CTRL

REC + OUT

REC AGC FILTER

AT ENVE FB

GND 2

REC LEVEL ADJ

PB AGC OUT

PB AGC FILTER

AT ENVE PEAKING

H SYNC IN

PB RF OUT

AT ENVE OUT

REC IN

Electrical characteristics (unless otherwise noted, Ta = 25°C, V

= 5.0V and f = 4.0MHz)

Parameter

Symbol Min. Typ. Max. Unit

Conditions

Measurement

circuit

Playback system

Quiescent current

Voltage gain CH-1

Voltage gain CH-2

Voltage gain differential

Frequency characteristic

2nd harmonic distortion

3rd harmonic distortion

Maximum output level

Crosstalk

(P)

Fig.1

VP1

Fig.1

VP2

Fig.1

2HD

-- 45

dBc

Fig.1

3HD

-- 45

dBc

Fig.1

OMP

1.0

1.5

P-P

Fig.1

-- 38 32

dBc

Fig.1

No signal

Pin 4 input = 0.3mV

P-P

, pin 1: L,

pin 14 output measurement

Pin 6 input = 0.3mV

P-P

, pin 1: H,

pin 14 output measurement

= | G

VP1

--G

VP2

Difference in pin 14 output level for f = 8.0 / 1.0MHz,
V

= 0.3mV

P-P

= 0.3mV

P-P

, 8.0MHz spurious

= 0.3mV

P-P

, 12.0MHz spurious

When pin 14 output 2nd harmonic distortion is 30dBc

Difference in pin 14 output level for pin 1: H / L

Design reference values.

(Fig. 1 measurement circuit, pin 8: "H" )

Video ICs

BA7181FS

Note: dBc: dB below carrier (used to express relative level from carrier reference for convenience sake).

Design reference values.

Parameter

Symbol Min.

Typ. Max.

Unit

Conditions

Playback system

Output DC offset

Input conversion noise

AGC output level

AGC control sensitivity

AGC amp frequency
characteristic

PB switch ON resistance

PRE CH 2 threshold voltage

PRE CH 1 threshold voltage

ENVE residual voltage

ENVE output level

ENVE saturation voltage

PB mode holding voltage

EE mode holding voltage

REC mode holding voltage

Pin 14 output DC offset for pin 1: H / L

Rg = 10

, input conversion of pin 14 output noise

= 0.3mV

P-P

, pin 18 output measurement

Pin 18 output difference for V

= 0.15

~ 0.6mV

P-P

Pin 18 output level difference for
f = 8.0 / 1.0MHz, V

= 0.3mV

P-P

Pin 7 impedance

Pin 1 DC voltage for channel 2 operation

Pin 1 DC voltage for channel 1 operation

Pin 13 output measurement with no signal

Pin 13 output measurement when pin 14
output = 400mV

P-P

Pin 13 output measurement for large signal

Pin 8 DC voltage for PB mode

Pin 8 DC voltage for REC MUTE mode

Pin 8 DC voltage for REC mode

ODC

150 mV

P-P

Fig.1

NIN

0.25

rms

Fig.1

AGC

250

300

350 mV

P-P

Fig.1

AGC

0.3

2.0

Fig.1

VAF

0.5

Fig.1

ON7

Fig.1

TH1H

3.5

Fig.1

TH1L

1.2

Fig.1

ENV1

0.7

1.0

Fig.1

ENV2

2.4

2.9

3.4

Fig.1

ENV3

4.0

4.5

Fig.1

TH10H

3.8

Fig.1

TH10M

2.2

2.8

Fig.1

TH10L

1.2

Fig.1

Measurement

circuit

(Fig. 1 measurement circuit, pin 8: "H" )

(unless otherwise noted, Ta = 25°C, V

= 5.0V, f = 4.0MHz and I

OAR

= 30mA

P-P

)

Parameter

Symbol Min.

Typ.

Max.

Unit

Recording system

Supply current

Recording AGC level

AGC control sensitivity

REC Amp frequency
characteristic

2nd harmonic distortion

3rd harmonic distortion

Cross modulation distortion

Maximum output level

Recording current load
characteristic

Mute attenuation ratio

AGC mode holding voltage

(R)

110

P-P

Fig.2

OAR

Fig.2

OAR

0.3

1.5

Fig.2

OAF

1.5

Fig.2

2HD

dBc

Fig.2

3HD

dBc

Fig.2

CMD

dBc

Fig.2

OMR

P-P

Fig.2

ORL

0.35

Fig.2

dBc

Fig.2

TH15H

2.7

Fig.2

TH15L

1.2

Fig.2

No signal

Pin 12 input = 125mV

P-P

, pin 7 output measurement

Pin 7 output level difference for pin 12
input = 62.5mV

P-P

and 250mV

P-P

Pin 7 output level difference for f = 8.0 / 1.0MHz,
pin 12 input = 125mV

P-P

Pin 12 input = 125mV

P-P

, 8MHz spurious

Pin 12 input = 125mV

P-P

, 12.0MHz spurious

4.0MHz

630kHz spurious

When pin 7 output 2nd harmonic distortion is 30dB

Pin 7 output level difference for load L: 8.2 ~ 12

Pin 7 output level difference for pin 8: M / H

Pin 15 DC voltage to maintain recording AGC operation

Pin 15 DC voltage to maintain recording AGC stopped

Conditions

Measurement

circuit

(Pin 8 in Fig. 2 measurement circuit "L" )

Design reference values.

Part Number BA7181FS