Sanyo LA7256 Specifications

Monolithic Linear IC

Ordering number : EN4896

63095HA (OT) No. 4896-1/9

SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters

TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN

High-Fidelity Audio Signal Record/Playback

Processing Circuit for VCR Products

LA7256

Overview

The LA7256 provides the record and playback
amplification functions required for high-fidelity audio
signal processing in VCR systems. The record system
supports S-VHS and over-recording, and also supports the
provision of an adjustment-free record current by using a
constant-current regulated output scheme incorporating an
AGC circuit. The playback system consists of a high-gain
preamplifier with a small DC offset, and includes a built­in EP gain increasing function.

Functions

• Preamplifier (two channels)

• RF switching between CH1 and CH2

• Record AGC amplifier (for over-recording and S-VHS)

• Constant-current regulated output record amplifier

• Buffer amplifier that can be used in both record and
playback

Features

• Minimal number of required external components

• The playback amplifier output DC offset is small.

• Built-in EP mode gain emphasis

• Record AGC that handles three modes (for an
adjustment-free record current)

• Built-in buffer amplifier that can be used to construct an
active filter.

Package Dimensions

unit: mm

3067-DIP24S

Specifications

Maximum Ratings at Ta = 25°C

Operating Conditions at Ta = 25°C

Parameter Symbol Conditions Ratings Unit

Maximum supply voltage V

CC

max 7.0 V
Allowable power dissipation Pd max Ta ≤ 65°C 700 mW
Operating temperature Topr –10 to +65 °C
Storage temperature Tstg –55 to +150 °C

Parameter Symbol Conditions Ratings Unit

Recommended supply voltage V

CC

5.0 V

Operating supply voltage range V

CC

op 4.5 to 5.5 V

[LA7256]

SANYO: DIP24S

Operating Characteristics at Ta = 25°C, VCC= 5 V, in the specified test circuit

Note: 1. Measure the input noise voltage after passing the pin 3 output (playback FM output) through a 1.1 MHz low-pass filter.

2. 1.3 MHz (70 mVp-p) + 1.7 MHz (180 mVp-p)

No. 4896-2/9

LA7256

Parameter Symbol Conditions min typ max Unit
[Playback Mode]
Circuit current I

CCP

No input: the pin 14 influx current 13 18 23 mA

Voltage gain, CH1 G

VP1

Pin 20 input = 100 µVp-p, f = 1.5 MHz, pin 1 = low:

72.5 75.5 78.5 dB

measure the pin 3 output.

Voltage gain, CH2 G

VP2

Pin 17 input = 100 µVp-p, f = 1.5 MHz, pin 1 = high:

72.5 75.5 78.5 dB

measure the pin 3 output.

Voltage gain difference ∆G

VP

G

VP1

– G

VP2

–2 0 2 dB

EP gain emphasis ∆G

EP

Pin 20 input = 100 µVp-p, f = 1.5 MHz, pin 1 = low:

1.7 2.4 3.1 dB

the ratio of the pin 3 outputs when pin 2 is high/low

Frequency characteristics, CH1 f

P1

Pin 20 input = 100 µVp-p, pin 1 = low: the difference

–3.0 –1.0 0 dB

in the levels on pin 3 when f = 2.2 MHz and 1.0 MHz
Pin 17 input = 100 µVp-p, f = 1.5 MHz, pin 1 = high:

Frequency characteristics, CH2 f

P2

the difference in the levels on pin 3 when f = 2.2 MHz –3.0 –1.0 0 dB
and 1.0 MHz

Pin 17 input = 0, pin 20 input = 100 µVp-p, f = 1.5 MHz:

Crosstalk CH1 to CH2 CT

1 → 2

the difference in the pin 3 output levels when pin 1 goes –40 –35 dB
from low to high

Pin 20 input = 0, pin 17 output = 100 µVp-p, f = 1.5 MHz:

Crosstalk CH2 to CH1 CT

2 → 1

the difference in the pin 3 output levels when pin 1 goes –40 –35 dB
from high to low

Equivalent input noise voltage CH1

V

NP1

With pin 20 grounded through 0.01 µF and 1 Ω,

0.8 1.0 µVrms

pin 1 = low: the pin 3 noise in input equivalent

*1

Equivalent input noise voltage CH2

V

NP2

With pin 17 grounded through 0.01 µF and 1 Ω,

0.8 1.0 µVrms

pin 1 = high: the pin 3 noise in input equivalent

*1

Second harmonic distortion CH1 2THD

1

Pin 20 input = 100 µVp-p, f = 1.5 MHz, pin 1 = low:

–50 –40 dB

the second harmonic in the pin 3 output

Second harmonic distortion CH2 2THD

2

Pin 17 input = 100 µVp-p, f = 1.5 MHz, pin 1 = high:

–50 –40 dB

the second harmonic in the pin 3 output

Maximum output voltage CH1 V

OMP1

With the pin 20 input varying, f = 1.5 MHz, pin 1 = low:

2.0 Vp-p

when the pin 3 third harmonic distortion is –30 dB

Maximum output voltage CH2 V

OMP2

With the pin 17 input varying, f = 1.5 MHz, pin 1 = high:

2.0 Vp-p

when the pin 3 third harmonic distortion is –30 dB
Pin 17 and 20 inputs = 0, pin 1 = low, pin 2 = low (SP):

Output DC offset 1 ∆V

ODC1

the difference in the pin 3 DC level when pin 1 goes –30 0 +30 mV
from low to high

Pin 17 and 20 inputs = 0, pin 1 = low, pin 2 = high (EP):

Output DC offset 2 ∆V

ODC2

the difference in the pin 3 DC level when pin 1 goes –50 0 +50 mV
from low to high

Head switching: CH1 hold voltage V

HS1

The pin 1 DC voltage required to operate CH1 0 1.0 V

Head switching: CH2 hold voltage V

HS2

The pin 1 DC voltage required to operate CH2 3.0 V

CC

V

Playback mode switch

R

SW

Calculate from the voltage difference on pin 16

4.0 6.0 Ω

on resistance when the pin 16 influx current is 1 mA and 2 mA.
SP hold voltage V

2

SP The pin 2 voltage required to hold SP mode 0 1.0 V

EP hold voltage V

2

EP The pin 2 voltage required to hold EP mode 3.0 V

CC

V

PB hold voltage V

5L

The pin 5 voltage required to hold PB mode 0 1.0 V
[Record Mode]
Circuit current I

CCR

No signal, the pin 14 influx current 45 63 81 mA
Output current I

OR

Pin 9 input = 180 mVp-p, f = 1.5 MHz:

48 53 58 mAp-p

measure the pin 16 output
AGC control characteristics 1 ∆V

AGC1

Pin 9 input = 90 and 180 mVp-p, f = 1.5 MHz:

–0.5 –0.2 dB

the ratio of the pin 16 output levels
AGC control characteristics 2 ∆V

AGC2

Pin 9 input = 360 and 180 mVp-p, f = 1.5 MHz:

0.2 0.5 dB

the ratio of the pin 16 output levels
Cross modulation distortion

CMD

04

For a pin 9 input*2, the 0.4 MHz spurious signal

–40 dB

0.4 MHz component in the pin 16 output current
Cross modulation distortion

CMD

09

For a pin 9 input*2, the 0.9 MHz spurious signal

–40 dB

0.9 MHz component in the pin 16 output current

Continued on next page.

Continued from preceding page.

Test Circuit Diagram

No. 4896-3/9

LA7256

Parameter Symbol Conditions min typ max Unit

Over-record hold voltage V

11M

The pin 11 DC voltage for over-record mode 1.5 3.0 V
Over-record current ratio I

O-OV

Pin 9 input = 180 mVp-p, f = 1.5 MHz,

1.7 2.2 2.7 dB

pin 11 = middle level: measure the pin 16 output current
S-VHS hold voltage V

11H

The pin 11 DC voltage for S-VHS mode 3.5 V

CC

V

S-VHS current ratio I

O-SV

Pin 9 input = 180 mVp-p, f = 1.5 MHz, pin 11 = high:

–2.0 –2.6 –3.2 dB

measure the pin 16 output current
Record mute hold voltage 1 V

4L

The pin 4 DC voltage when record muting is off 0 1.0 V
Record mute hold voltage 2 V

4H

The pin 4 DC voltage when record muting is on 3.0 V

CC

V

Mute attenuation I

OR

, M

U

Pin 9 input = 180 mVp-p, f = 1.5 MHz, pin 4 = high:

–40 dB

measure the pin 16 output current
Record hold voltage V

5H

The pin 5 voltage required to hold record mode 3.0 V

CC

V
[Built-in Buffer]
Buffer I/O DC offset ∆V

BUF

–10 10 mV

Buffer frequency characteristics f

BUF

Pin 9 input = 180 mVp-p, f = 1/10 MHz –1 1 dB

Application Circuit Block Diagram

No. 4896-4/9

LA7256

Pin Functions

No. 4896-5/9

LA7256

Pin No. Symbol Pin internal equivalent circuit Function

1

2

3

4

5

6

A-HEAD PULSE

ES/SP

PB-FM OUT

REC MUTE

REC

GND

Low: 0 to 1.0 V → CH1
High: 3.0 to V

CC

→ CH2

Low: 0 to 1.0 V → SP
High: 3.0 to V

CC

→ EP

Low: 0 to 1.0 V → Mute off
High: 3.0 to V

CC

→ Mute on

Low: 0 to 1.0 V → PB
High: 3.0 to V

CC

→ REC

Ground for the playback output stage and record circuits

Continued on next page.

Continued from preceding page.

No. 4896-6/9

LA7256

Pin No. Symbol Pin internal equivalent circuit Function

7

8

9

10

11

12

BUFF IN

BUFF OUT

REC FM IN

AGC FILT

REC MODE

REC OUT GND

DC voltage = 1/2 V

CC

Record amplifier input

Detects the record amplifier AGC detector output

Low: 0 to 1.0 V → Normal
Middle: 1.5 to 3.0 V → Over-record
High: 3.5 V to V

CC

→ S-VHS

Ground for the record output circuits

Continued on next page.

Continued from preceding page.

No. 4896-7/9

LA7256

Pin No. Symbol Pin internal equivalent circuit Function

13

14

15

16

17

18

REC-CURR-ADJ

V

CC

REC BIAS

REC OUT

CH2-IN

PSW2

Converts the record output current output to a voltage.

Input block for the record current amplifier

Switch for record current output and playback mode on
On in PB mode

Playback amplifier CH2 input

CH2 head current supply

Continued on next page.

No. 4896-8/9

LA7256

Continued from preceding page.

Pin No. Symbol Pin internal equivalent circuit Function

19

20

21

22

23

24

FILT2

CH1-IN

PB GND

FILT1

NC

PSW1

Generates the playback amplifier CH2 DC bias.

Playback amplifier CH1 input

Ground for the playback amplifier

Generates the playback amplifier CH1 DC bias.

Record amplifier CH2 head current supply

PS No. 4896-9/9

LA7256

This catalog provides information as of June, 1995. Specifications and information herein are subject to change
without notice.

■ No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace
equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of
which may directly or indirectly cause injury, death or property loss.

■ Anyone purchasing any products described or contained herein for an above-mentioned use shall:
➀ Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and

distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all
damages, cost and expenses associated with such use:

➁ Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on

SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees
jointly or severally.

■ Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for
volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied
regarding its use or any infringements of intellectual property rights or other rights of third parties.