TDA1072AT_CNV.pdf

INTEGRATED CIRCUITS

DATA SHEET

TDA1072AT

AM receiver circuit

Product speciﬁcation

File under Integrated Circuits, IC01

March 1989

Philips Semiconductors

Product speciﬁcation

AM receiver circuit

TDA1072AT

GENERAL DESCRIPTION

The TDA 1072AT integrated AM receiver circuit performs the active and part of the filtering functions of an AM radio

receiver. It is intended for use in mains-fed home receivers and car radios. The circuit can be used for oscillator

frequencies up to 50 MHz and can handle RF signals up to 500 mV. RF radiation and sensitivity to interference are

minimized by an almost symmetrical design. The voltage-controlled oscillator provides signals with extremely low

distortion and high spectral purity over the whole frequency range even when tuning with variable capacitance diodes.

If required, band switching diodes can easily be applied. Selectivity is obtained using a block filter before the IF amplifier.

Features

Inputs protected against damage by static discharge

Gain-controlled RF stage

Double balanced mixer

Separately buffered, voltage-controlled and temperature-compensated oscillator, designed for simple coils

Gain-controlled IF stage with wide AGC range

Full-wave, balanced envelope detector

Internal generation of AGC voltage with possibility of second-order filtering

Buffered field strength indicator driver with short-circuit protection

AF preamplifier with possibilities for simple AF filtering

Electronic standby switch.

QUICK REFERENCE DATA

PARAMETER

CONDITIONS

SYMBOL

MIN.

TYP.

MAX.

UNIT

Supply voltage range

V P

7.5

Supply current range

I P

RF input voltage for

N/N = 6 dB at m = 30%

V I

1.5

RF input voltage for 3%

total harmonic distortion

(THD) at m = 80%

V I

500

AF output voltage with

V I = 2 mV; f I = 1 MHz;

m = 30% and f m = 400 Hz

V O(AF)

310

AGC range: change of V I

for 1 dB change of V O(AF)

Field strength indicator

voltage at V I = 500 mV;

R L(9) = 2.7 k

V IND

2.8

PACKAGE OUTLINE

16-lead mini-pack; plastic (SO16; SOT109A); SOT109-1; 1996 August 13.

March 1989

Philips Semiconductors

Product speciﬁcation

AM receiver circuit

TDA1072AT

(1) Coil data: TOKO sample no. 7XNS-A7523DY; L1: N1/N2 = 12/32; Q o = 65; Q B = 57.

Filter data: Z F = 700 W at R 3-4 = 3 k W ; Z 1 = 4.8 k W .

Fig.1 Block diagram and test circuit (connections shown in broken lines are not part of the test circuit).

March 1989

Philips Semiconductors

Product speciﬁcation

AM receiver circuit

TDA1072AT

FUNCTIONAL DESCRIPTION

Gain-controlled RF stage and mixer

The differential amplifier in the RF stage employs an AGC negative feedback network to provide a wide dynamic range.

Very good cross-modulation behaviour is achieved by AGC delays at the various signal stages. Large signals are

handled with low distortion and the S/N ratio of small signals is also improved. Low noise working is achieved in the

differential amplifier by using transistors with a low base resistance.

A double balanced mixer provides the IF output to pin 1.

Oscillator

The differential amplifier oscillator is temperature compensated and is suitable for simple coil connection. The oscillator

is voltage-controlled and has little distortion or spurious radiation. It is specially suitable for electronic tuning using

variable capacitance diodes. Band switching diodes can easily be applied using the stabilized voltage V 11-16 . An extra

buffered oscillator output is available for driving a synthesizer. If this is not needed, resistor R L(10) can be omitted.

Gain-controlled IF ampliﬁer

This amplifier comprises two cascaded, variable-gain differential amplifier stages coupled by a band-pass filter. Both

stages are gain-controlled by the AGC negative feedback network.

Detector

The full-wave, balanced envelope detector has very low distortion over a wide dynamic range. The residual IF carrier is

blocked from the signal path by an internal low-pass filter.

AF preampliﬁer

This stage preamplifies the audio frequency output. The amplifier output stage uses an emitter follower with a series

resistor which, together with an external capacitor, provides the required low-pass filtering for AF signals.

AGC ampliﬁer

The AGC amplifier provides a control voltage which is proportional to the carrier amplitude. Second-order filtering of the

AGC voltage achieves signals with very little distortion, even at low audio frequencies. This method of filtering also gives

a fast AGC settling time which is advantageous for electronic search tuning. The AGC settling time can be further

reduced by using capacitors of smaller value in the external filter. The AGC voltage is fed to the RF and IF stages via

suitable AGC delays. The capacitor at pin 7 can be omitted for low-cost applications.

Field strength indicator output

A buffered voltage source provides a high-level field strength output signal which has good linearity for logarithmic input

signals over the whole dynamic range. If field strength information is not needed, R L(9) can be omitted.

Standby switch

This switch is primariIy intended for AM/FM band switching. During standby mode the oscillator, mixer and demodulator

are switched off.

Short-circuit protection

All pins have short-circuit protection to ground.

March 1989

Philips Semiconductors

Product speciﬁcation

AM receiver circuit

TDA1072AT

RATINGS

Limiting values in accordance with the Absolute Maximum Rating System (IEC 134)

PARAMETER

CONDITIONS

SYMBOL

MIN.

MAX.

UNIT

Supply voltage

V P = V 13-16

V 13

Input voltage

pins 14-15

V 14-15

pins 14-16

V 14-16

V P

pins 15-16

V 15-16

V P

pins 14-16

V 14-16

0.6

pins 15-16

V 15-16

- 0.6

Input current

(pins 14 and 15)

I 14-15

200

Total power dissipation (note 1)

P tot

300

Operating ambient temperature range

T amb

- 40

+ 80

° C

Storage temperature range

T stg

+ 150

Junction temperature

T j

+ 125

Note

1. Mounted on epoxiprint.

THERMAL RESISTANCE

From junction to ambient

R th j-a

300 K/W

160 K/W (1)

Note

1. Mounted on epoxiprint.

March 1989

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