Philips TEA6100 Datasheet

INTEGRATED CIRCUITS

DATA SH EET

TEA6100

FM/IF system and
microcomputer-based tuning
interface

Product specification
File under Integrated Circuits, IC01

August 1987

Philips Semiconductors Product specification

FM/IF system and microcomputer-based
tuning interface

GENERAL DESCRIPTION

The TEA6100 is a FM/IF system circuit intended for
microcomputer controlled radio receivers. The circuit
includes highly sensitive analogue circuitry. The digital
circuitry, including an I2C bus, controls the analogue
circuitry and the AM/FM tuning and stop information for the
microcomputer.

Features

• 4-stage symmetrical IF limiting amplifier

• Software selectable AM or FM input

• Symmetrical quadrature demodulator

• Single-ended LF output stage

• D.C. output level determined by the input signal

• Semi-adjustable AM and FM level voltage

• Multi-path detector/rectifier/amplifier circuitry

• 3-bit level information and 3-bit multi-path information

TEA6100

• Signal dependent 'soft' muting circuit; externally
adjustable

• Reference voltage output (FM mode only)

• 8-bit AM/FM frequency counter with selectable counter

resolution

• Possibility to measure the AM IF frequency at 460 kHz
(250 Hz resolution) and 10,7 MHz (500 Hz resolution)

• Reference frequency can be directly connected to the
reference frequency output of a frequency synthesizer
(TSA6057, 40 kHz) .

PACKAGE OUTLINE

20-lead DIL; plastic (SOT146); SOT146-1; 1996 August 13.

August 1987 2

Philips Semiconductors Product specification

FM/IF system and microcomputer-based

TEA6100

tuning interface

QUICK REFERENCE DATA

PARAMETER CONDITIONS SYMBOL MIN. TYP. MAX. UNIT

P1

P1

, V

+ I

P2

P2

Supply voltage V
Supply current I
FM/IF sensitivity −3 dB before

limiting V

i

Signal plus noise ∆f = 75 kHz;

to noise ratio VI= 10 mV (S + N)/N − 85 − dB

Audio output voltage

after limiting ∆f = 22,5 kHz V

AM suppression V

= 600 µV

IFM

o

to 600 mV;
m = 0,3 AMS − 60 − dB

Frequency counter

sensitivity
AM pin 19,

f = 10,7 MHz V
f = 460 kHz V

i(AM)
i(AM)

FM pin 18,

f = 10,7 MHz V

i(FM)

Resolution of the reference

frequency counter frequency of

40 kHz;

AM IF = 460 kHz f

IF = 10,7 MHz f

FM f

(AM) − 250 − Hz

s

(AM) − 500 − Hz

s

(FM) − 6,4 − kHz

s

− 8,5 − V

− 35 − mA

− 15 −µV

− 200 − mV

− 45 −µV

− 20 −µV

− 45 −µV

August 1987 3

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August 1987 4

Philips Semiconductors Product specification

FM/IF system and microcomputer-based

tuning interface

Fig.1 Block diagram.

TEA6100

Philips Semiconductors Product specification

FM/IF system and microcomputer-based
tuning interface

PINNING

1V

P1

2 MUTE IN mute input
3 LA OUT level amplifier output
4 RT/A IN rectifier/amplifier input
5 RT/A OUT rectifier/amplifier output
6F

ref

7 DGND digital ground
8V

P2

9 SCL serial clock line; I
10 SDA serial data line; I
11 LF OUT audio output signal
12 Q-DET phase shift for quadrature

13 Q-DET phase shift for quadrature

14 LADJ level amplifier adjustment
15 V

ref

16 FB DEC decoupled feedback
17 FB DEC decoupled feedback
18 INPUT 1 FM/AM IF input
19 INPUT 2 AM/FM IF input
20 AGND analogue ground

analogue supply voltage

reference frequency input

digital supply voltage

2

C bus

2

C bus

detector

detector

reference voltage

TEA6100

Fig.2 Pinning diagram.

FUNCTIONAL DESCRIPTION (see Figs 1 and 16) The IF amplifier consists of four balanced limiting amplifier stages, two separate inputs (AM and FM) and one output.

Software programming (see Table 2; Figs 4 and 5) allows the input signals (AM/FM) to be inserted on either input (pin
18 or 19). The output drives the frequency counter and via the mute stage, drives the quadrature detector. The output of
the quadrature detector is applied to an audio stage (which has a single-ended output). The AM/FM level amplifier, which
is driven by 5 IF level detectors, generates a signal dependent d.c. voltage. The level output voltage is used internally to
control the mute stage and, if required, the signal can be used externally to control the stereo channel separation and
frequency response of a stereo decoder. The signal is also feed to the analogue-to-digital converter (ADC). Due to the
front-end spread in the amplification, the level voltage is made adjustable (LADJ, pin 14). The level voltage amplifier
controls the mute stage and this insures the −3 dB limiting point remains constant, independent of the front-end spread.
AM and FM mode have different front-end circuitry, therefore LADJ must be adjustable for both inputs.

The output voltage of the level amplifier is dependent upon the field strength of the input signal. The multi-path of the FM
signal exists in the AM modulation of the input signal. The following method is used to determine the level information
and the amount of multi-path (as a DC voltage):

• the IF level detector detects the multi-path and feds the signal, via the level amplifiers, to the external bandpass filter
(pin 3) and ADC1

• the signal is then fed to an internal rectifier

• the rectified signal is then fed to an amplifier, so at pin 5 the DC level information is externally available and internally

used by ADC2

In the FM mode, the DC information concerning the multi-path is available at pin 5 and the level information is available
at pin 3.

August 1987 5

Philips Semiconductors Product specification

FM/IF system and microcomputer-based

TEA6100

tuning interface

In the AM mode, the level information at pin 3 cannot be directly used owing to AM modulation on the output signal of
the level amplifier. This signal requires filtering, which is achieved by the following method:

• the multiplexer is switched to a position which causes the signal to be applied to the attenuator

• after attenuation the signal is fed to an amplifier (the resultant gain of attenuator and amplifier is unity), after

amplification the signal is filtered by an internal resistor and external capacitor

• after filtering the signal is applied to ADC2 and is externally available

In AM mode pin 5 contains the level information.
The voltages on pin 3 and 5 are converted into two 3-bit digital words by the ADC, which can then be read out by the

I2C bus. The meaning of the 3- bit words is shown in Table 1.

Table 1 3-bit words

WORD

FM AM

1 multipath level without modulation
2 level level with modulation

The FM modulated signal is converted into an audio signal by the symmetrical quadrature detector. The main advantage
of such a detector is that it requires few external components.

POSITION

An FM signal requires good AM suppression, and as a result, the IF amplifiers must act as limiters. To achieve good
suppression on small input signals the IF amplifiers must have a high gain and thus a high sensitivity. High sensitivity is
an undesirable property when used in car radio applications, this problem is solved by having an externally adjustable
mute stage to control the overall sensitivity of the device.

The IF mute stage is controlled by the level amplifier (soft muting) and is only active in FM mode. If the input falls below
a predetermined level, the mute stage becomes active. To avoid the 'ON/OFF' effect of the audio signal due to
fluctuations of the input signal, the mute stage is activated rapidly but de-activated slowly. The mute stage is de-activated
slowly, via a current source and an external capacitor at pin 2, to avoid aggressive behaviour of the audio signal. It is
possible to adjust the '−3 dB limiting point' of the audio output via the level voltage due to the level signal being externally
adjustable. If hard muting is required then pin 2 must be switched to ground.

The 8-bit counter allows accurate stop information to be obtained, because exact tuning is achieved when the measured
frequency is equal to the centre frequency of the IF filter.

To measure the input frequency, the number of pulses which occur in a defined time must be counted. This defined time
is refered to as 'window'. A wide window indicates a long measuring time and therefore a high accuracy. The counter
resolution is defined as Hertz per count. Due to the TEA6100 having to measure the IF frequencies of AM and FM, the
counter resolution must be adjustable (different channel spacing). The counter resolution depends on the setting of
dividers 1 (N1), divider 2 (N2) and the reference frequency (F
software (see section PROGRAMMING INFORMATION). In Table 3 the window and counter resolution has been
calculated for a reference frequency of 40 kHz. The accuracy is controlled by bit 7 of the input word. Although the
resolution is the same for bit 7 = logic 0 and bit 7 = logic 1, the width of the window doubles when bit 7 = logic 1.

• bit 7 = 0, accuracy = ± counter resolution

• bit 7 = 1, accuracy = ± 1⁄2 counter resolution

). The divider ratios of N1 and N2 are controlled by

ref

August 1987 6

Philips Semiconductors Product specification

FM/IF system and microcomputer-based

TEA6100

tuning interface

Communication between TEA6100 and the microcomputer is via a two wire bidirectional I2C bus. The power supply lines
are fully isolated to avoid cross talk between the digital and analogue parts of the circuit.

Fig.3 Input data format waveforms.

Table 2 Input bits

BIT FUNCTION LOGIC 0 LOGIC 1 SEE Fig.5 AND 6

1 reference frequency 32 kHz 40 kHz A
2 IF mode AM FM B
3 IF input pin 19 pin 18 C
4 counter input 460 kHz 10,7 MHz D
5 counter mode AM FM E
6 resolution divide by 8 divide by 1 F
7 accuracy LOW HIGH G
8 test mode OFF ON H

August 1987 7

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August 1987 8

Philips Semiconductors Product specification

FM/IF system and microcomputer-based

tuning interface

Fig.4 Output data format waveforms.

TEA6100

Philips Semiconductors Product specification

FM/IF system and microcomputer-based
tuning interface

TEA6100

Fig.5 Switch positions, analogue part (switches drawn in logic 0 state).

August 1987 9