NSC LM1818N Datasheet

LM1818 Electronically Switched Audio Tape System

LM1818 Electronically Switched Audio Tape System

April 1987

General Description

The LM1818 is a linear integrated circuit containing all of the
active electronics necessary for building a tape recorder
deck (excluding the bias oscillator). The electronic functions
on the chip include: a microphone and playback preamplifi­er, record and playback amplifiers, a meter driving circuit,
and an automatic input level control circuit. The IC features
complete internal electronic switching between the record
and playback modes of operation. The multipole switch
used in previous systems to switch between record and
playback modes is replaced by a single pole switch, thereby
allowing for more flexibility and reliability in the recorder de­sign.*

*Monaural operation,

Figure 9

.

Typical Applications

Features

Y

Electronic record/play switching

Y

85 dB power supply rejection

Y

Motional peak level meter circuitry

Y

Low noise preamplifier circuitry

Y

3.5V to 18V supply operation

Y

Provision for external low noise input transistor

FIGURE 1. Stereo Application Circuit (Left Channel Shown), V

e

15V

S

TL/H/7894– 1

Order Number LM1818N

See NS Package Number N20A

C

1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.

TL/H/7894

Absolute Maximum Ratings

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Supply Voltage 18V

Package Dissipation, (Note 1) 1560 mW

Storage Temperature

b

65§Ctoa150§C

Operating Temperature 0

Ctoa70§C

§

Junction Temperature 150§C

Minimum Voltage on Any Pin

Maximum Voltage on Pins 2 and 5 0.1 V

Maximum Current Out of Pin 14 5 mA

b

0.1 V

DC

DC

DC

Lead Temperature (Soldering, 10 sec.) 260§C

Electrical Characteristics V

CC

e

6V, T

e

25§C, See Test Circuits

A

(Figures 2

and

3)

Parameter Conditions Min Typ Max Units

Operating Supply Voltage Range 3.5 18 V

Supply Current Test Circuit

(Figure 2)

512 mA

DC

Turn-ON Time Externally Programmable 50 400 ms

Playback Signal to Noise DIN Eq. (3180 and 120 ms), 20 –20 kHz,

e

R

0, Unweighted, V

S

at 400 Hz

Record Signal to Noise Flat Gain, 20–20 kHz, R

ALC OFF, V
at 1 kHz, Unweighted

REF

e

e

1mV 74 dB

REF

e

0,

S

1mV 69 dB

Fast Turn-ON Charging Current Pins 16 and 17 200 mA

Record and Playback Preamplifier fe100 Hz
Open Loop Voltage Gain

100 dB

Preamplifier Input Impedance Pin 16 or Pin 17 50 kX

Preamplifier Input Referred PSRR 1 kHz Ð Flat Gain 85 dB

Bias Voltage on Pin 18 in Play Mode
or Pin 15 in Record Mode

Monitor Amplifier Input Pins 11 and 12
Bias Current

Monitor Amplifier Open Record or Playback, fe100 Hz
Loop Voltage Gain

0.5 V

0.5 mA

80 dB

Monitor Output Current Capability Pins 9 and 10, Source Current Available 400 750 mA

Monitor Amplifier Output Swing R

e

10k, AC Load 1.2 1.65 Vrms

L

THD, All Amplifiers At 1 kHz, 40 dB Closed Loop Gain 0.05 %

Record-Playback Switching Time As in Test Circuit 50 ms

Input ALC Range DVINfor DV

Input Voltage on ALC Pin for
Start of ALC Action

e

8dB 40 dB

OUT

25 mVrms

ALC Input Impedance 2kX

ALC Attack Time C13e10 mF7ms

ALC Decay Time R17

e %

Meter Output Gain 100 mVrms at 1 kHz into Pin 4 800 mV

Meter Output Current Capability 2 mA

Note 1: For operation in ambient temperatures above 25§C, the device must be derated based on a 150§C maximum junction temperature and a thermal resistance

C/W junction to ambient.

of 80

§

e

10 mF 30 sec

, C13

DC

DC

2

Test Circuits

TL/H/7894– 2

FIGURE 2. General Test Circuit

3

Test Circuits (Continued)

FIGURE 3. Noise Test Circuit

4

TL/H/7894– 3

Equivalent Schematic Diagram

FIGURE 4

5

TL/H/7894– 4