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

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

5.0 V

Operating supply voltage range V

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

VP1

– G

VP2

–2 0 2 dB

EP gain emphasis ∆G

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

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

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

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

Equivalent input noise voltage CH2

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

Second harmonic distortion CH1 2THD

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

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

Playback mode switch

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

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

EP hold voltage V

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

PB hold voltage V

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

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

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

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

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

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

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

Mute attenuation I

, M

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

The pin 5 voltage required to hold record mode 3.0 V

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

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