ROHM BA7181FS Datasheet

1

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 chan­nel 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 imped­ance)well, and gives stable recording characteris­tics. 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

V

CC

7.0 V

Pd 937.5

∗

mW

Topr

°C

Tstg °C

∗

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°C.

– 20 ~ + 65
– 55 ~ + 150

•

Recommended operating (Ta = 25°C)

Parameter Symbol Min. Typ. Max. Unit Conditions

Playback / recording (voltage range)

V

CC

4.5 5.0 5.5 V 11pin

䊊Not designed for radiation resistance.

2

Video ICs BA7181FS

•

Block diagram

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+

RF

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

V

CC

VCC

•

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

Iq

(P)

— 18 45 mA Fig.1

G

VP1

54 57 60 dB Fig.1

G

VP2

54 57 60 dB Fig.1

∆G

VP

— 0 1 dB Fig.1

∆G

Vf

–7–3 0 dB Fig.1

2HD

P

—–45 — dBc Fig.1

3HD

P

—–45 — dBc Fig.1

V

OMP

1.0 1.5 — V

P-P

Fig.1

CT

P

—– 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

VP= | GVP1—GVP2 |

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

IN = 0.3mVP-P

VIN = 0.3mVP-P, 8.0MHz spurious
V

IN = 0.3mVP-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” )

3

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 = 10Ω, input conversion of pin 14 output noise
V

IN

= 0.3mV

P-P

, pin 18 output measurement

Pin 18 output difference for V

IN

= 0.15

~ 0.6mV

P-P

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

IN

= 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

∆V

ODC

— 0 150 mV

P-P

Fig.1

V

NIN

— 0.25 — µVrms

Fig.1

V

AGC

250 300 350 mV

P-P

Fig.1

∆V

AGC

— 0.3 2.0 dB

Fig.1

∆G

VAF

— 0.5 — dB

Fig.1

R

ON7

—4—

Ω

Fig.1

V

TH1H

3.5 — V

CC

V

Fig.1

V

TH1L

0 — 1.2 V

Fig.1

V

ENV1

— 0.7 1.0 V

Fig.1

V

ENV2

2.4 2.9 3.4 V

Fig.1

V

ENV3

4.0 4.5 — V

Fig.1

V

TH10H

3.8 — V

CC

V

Fig.1

V

TH10M

2.2 — 2.8 V

Fig.1

V

TH10L

0 — 1.2 V

Fig.1

Measurement

circuit

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

(unless otherwise noted, Ta = 25°C, VCC = 5.0V, f = 4.0MHz and IOAR = 30mAP-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
AGC mode holding voltage

Iq

(R)

— 72 110 mA

P-P

Fig.2

I

OAR

27 30 33 mA Fig.2

∆I

OAR

— 0.3 1.5 dB Fig.2

∆I

OAF

— – 1.5 — dB Fig.2

2HD

R

— – 45 — dBc Fig.2

3HD

R

— – 50 — dBc Fig.2

CMD

R

— – 50 — dBc Fig.2

I

OMR

40 50 — mA

P-P

Fig.2

∆I

ORL

— – 0.35 — dB

Fig.2

MU

R

— – 45 –38 dBc

Fig.2

V

TH15H

2.7 — V

Fig.2

V

TH15L

0 — 1.2 V

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 ~ 12µH
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

V

CC

Measurement

circuit

(Pin 8 in Fig. 2 measurement circuit “L” )

∗

Design reference values.