ROHM BA7182AS Datasheet

1

Video ICs

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

BA7182AS

The BA7182AS 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 59dB
(Typ.), and has a low-noise preamplifier. Designed
for VHS-band operation with low external parts
count. The IC has 2 circuits for 2-head VCR applica­tions.

2) Two playback output systems (throgh output and
AGC output). The AGC output level is 270mV

P-P

(Typ.) ; suitable for FM brightness signal output.

3) Auto-tracking interface for automated tracking
adjustment. An integrate and hold detector is used
to reduce the load on the microcontroller.

4) The recording amplifier uses constant-current BLT
drive that handles load variations (i.e. headimped­ance) well, and gives stable recording characteris­tics. A single circuit is provided for 2-head VCR use.

5) Built-in recording level AGC means adjustment of
FM recording current is not necessary.

6) Head switches for 2-channel PRE / REC system
provided.

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

•

Absolute maximum ratings (Ta = 25°C)

•

Recommended operating conditions (Ta = 25°C)

Parameter

Symbol Limits Unit

7.0 V
mW

Topr °C
Tstg °C

V

CC

1100

∗

Pd

– 20 ~ + 75
– 55 ~ + 125

Applied voltage
Power dissipation
Operating temperature
Storage temperature

∗

Reduced by 11mW for each increase in Ta of 1°C over 25°C (free air).

Parameter Symbol Min. Typ. Max. Unit Conditions

V

CC

4.5 5.0 5.5 V 12pin

Playback / recording

䊊Not designed for radiation resistance.

2

Video ICs BA7182AS

•

Block diagram

221

2

3

4

5

6

7

8

9

10

11

21

20

19

18

17

16

15

14

13

12

GND 2

V

CC

–

+

REC OUT

DET

HPF

AGC

1k

REC

PREPRE

DET

AGC

– –

+

HPF

DET

RF

DFF IN

DET FILTER

HOLD FILTER

REC DCFB

PRE IN 1

PRE IN 2

GND 1

REC AGC FILTER

REC LEVEL ADJ

H SYNC IN

(REC OUT 1)

(REC OUT 2)

VCC

REC EQ

PB AGC OUT

PB / EE / REC CTRL

REC IN

PB AGC FILTER

PB RF OUT

AT ENVE DET ADJ

AT ENVE HOLD OUT

EP / SP CTRL

S / H

PRE / REC

LOGIC

–

MUTE

3

Video ICs BA7182AS

•

Electrical characteristics (unless otherwise noted, Ta = 25°C, VCC = 5.0V and f = 4.0MHz)

Parameter

Measurement

circuit

Fig.1
Fig.1

Fig.1
Fig.1
Fig.1
Fig.1
Fig.1
Fig.1

Fig.1
Fig.1

Fig.1
Fig.1

Fig.1
Fig.1
Fig.1

Fig.1
Fig.1

Fig.1
Fig.1

Fig.1
Fig.1
Fig.1
Fig.1

Conditions

〈Playback system〉 (Pin 15: H)
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
Output DC offset

Input conversion noise
AGC output level

AGC control sensitivity
AGC frequency

characteristic
PB switch ON resistance
PRE ch 2 holding voltage
PRE ch 1 holding voltage

ENVE output level SP-2
ENVE sensitivity curve

ENVE saturation voltage
ENVE residual voltage
EP mode

holding

voltage

SP mode

holding

voltage

No signal
Pin 5 input = 0.3mV

P-P

, pin 1: L,

pin 18 output measurement
Pin 7 input = 0.3mV

P-P

, pin 1: H,

pin 18 output measurement

Difference in pin 18 output level for
f = 8.0 / 1.0MHz, V

IN

= 0.3mV

P-P

VIN = 0.3mV

P-P

, 8.0MHz spurious

V

IN

= 0.3mV

P-P

, 12.0MHz spurious,

guaranteed design value.
When pin 18 output 2nd harmonic distortion is

–

30dBc
Difference in pin 18 output level for pin 1: H / L.
Pin 18 output DC offset for pin 1: H / L.
Rg = 10Ω, input conversion of pin 18 output

noise, guaranteed design value.
V

IN

= 0.3mV

P-P

Pin 14 output measurement

Pin 14 output level difference for V

IN

= 0.15 and 0.6mV

P-P

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

IN

= 0.3mV

P-P

.
Pin 8 impedance
Pin 1 DC voltage for ch 2 operation
Pin 1 DC voltage for ch 1 operation
Pin 20 output measurement when pin 21 = L

and pin 18 output = 250mV

P-P

Pin 21 = L, Pin 20 output measurement for large signal
Pin 21 = L, Pin 20 output measurement for no signal
Pin 21 DC voltage for EP mode
Pin 21 DC voltage for SP mode

—

Symbol Min. Typ. Max. Unit

— 26 42 mA

G

VP1

56.5 59 61.5 dB

G

VP2

56.5 59 61.5 dB

∆

GVP – 101dB

∆

GVf – 6 – 3 – 1dB

2HD

P

— – 45 – 35 dBc

3HD

P

— – 50 – 35 dBc

V

OMP

1.0 1.5 — V

P-P

CTP— – 38 – 33 dBc

∆

V

ODC

– 150 0 150 mV

P-P

V

NIN

— 0.25 1.0 µV

rms

V

AGC

220 270 320

∆

V

AGC

— 0.3 2 dB

∆

G

VAF

– 2 0.5 2 dB

R

ON8

— 510 Ω

V

TH1H

3.5 — V

CC

V

V

TH1L

0 — 1.2 V

V

EN-S2

1.4 2.2 3.0 V

P

CRV

150 200 250

%

V

EN-MA

4.6 4.9 — V
— 0.1 0.4 V

V

TH21H

3.5 — V

CC

V

V

TH21L

0 — 1.2 V

V

EN-MI

I

q (P)

mV

P-P

∆GVP = G

VP1

–

G

VP2