TDA4470-MFLG3Y - Atmel Corporation

Features

•

5V Supply Voltage

•

Active Carrier Generation by FPLL (Frequency-Phase-Locked Loop) Principle for True

Synchronous Demodulation

•

VCO Circuit Operates at Picture Carrier Frequency, the VCO frequency

is Switchable for L’-mode

•

Alignment-free AFC without External Reference Circuit, Polarity of the

AFC Curve is Switchable

•

VIF-AGC for Negatively Modulated Signals (Peak Synchronous

Detection) and for Positive Modulation (Peak White/Black Level

Detector)

•

Tuner AGC with Adjustable Take-over Point

•

Alignment-free Quasi Parallel Sound (QPS) Mixer for FM/NICAM Sound IF Signals

•

Intercarrier Output Signal is Gain Controlled (Necessary for Digital Sound Processing)

•

Complete Alignment-free AM Demodulator with Gain Controlled AF Output

•

Separate SIF-AGC with Average Detection

•

Two Independent SIF Inputs

•

Parallel Operation of the AM Demodulator and QPS Mixer (for NICAM-L Stereo Sound)

•

Pb-free Package, which is Compliant with Requirements of RoHS

Benefits

•

Linear Video Demodulation

•

Good Pulse Response

•

Excellent Intermodulation Figures

1. Description

The TDA4470 is an integrated bipolar circuit for multistandard video/sound IF

(VIF/SIF) signal processing in TV/VCR and multimedia applications. The circuit pro-

cesses all TV video IF signals with negative modulation (e.g., B/G standard), and the

FM/NICAM sound IF signals.

Multistandard

Video-IF and

Quasi Parallel

Sound

Processing IC

TDA4470

Rev. 4803C–TVVCR–10/05

4803C–TVVCR–10/05

TDA4470

Figure 1-1. Block Diagram

AGC

(VIF)

Tuner

AGC

(SIF)

Tuner

SIF 2

SIF 1

VCO

phase shift

AFC

Standard

Supply

L' switch

VCO

Loop

filter

Offset

comp.

(optional)

FPLL 0°

90°

VIF amp

VIF

AGC

Take-over

point

SIF input

switch

AGC

4, 9,16

13 Standard

switch

23 V

Ref

Intercarrier

(FM/NICAM)

FM det.

AM det.

SIF amp

25 AF

(AM)

AFC

Video

Video det.

Control

19 AFC

switch

4803C–TVVCR–10/05

TDA4470

2. Circuit Description

2.1 Vision IF Amplifier

The video IF signal (VIF) is fed through a SAW filter to the differential input (pins 6-7) of the VIF

amplifier. This amplifier consists of three AC-coupled amplifier stages. Each differential amplifier

is gain controlled by the automatic gain control (VIF-AGC). The output signal of the VIF amplifier

is applied to the FPLL carrier generation and the video demodulator.

2.2 Tuner-and VIF-AGC

At pin 8, the VIF-AGC charges/discharges the AGC capacitor to generate a control voltage for

setting the gain of the VIF amplifier and tuner in order to keep the video output signal at a con-

stant level. Therefore, the synchronous level of the demodulated video signal is the criterion for

a fast charge/discharge of the AGC capacitor. For positive modulation (e.g., L standard) the

peak white level of the video signal controls the charge current. In order to reduce the reaction

time for positive modulation, where a large time constant is needed, an additional black level

detector controls the discharge current in the event of decreasing VIF input signal. The control

voltage (AGC voltage at pin 8) is transferred to an internal control signal, and is fed to the tuner

AGC to generate the tuner AGC current at pin 11 (open collector output). The take-over point of

the tuner AGC can be adjusted at pin 10 by a potentiometer or an external DC voltage (from an

interface circuit or microprocessor).

2.3 FPLL, VCO and AFC

The FPLL (Frequency-Phase-Locked Loop) circuit consists of a frequency and phase detector to

generate the control voltage for the VCO tuning. In locked mode, the VCO is controlled by the

phase detector, in unlocked mode, the frequency detector is superimposed. The VCO operates

with an external resonance circuit (L and C in parallel) and is controlled by internal varicaps. The

VCO control voltage is also converted to a current and represents the AFC output signal at pin

22. At the AFC switch (pin 19) three operating conditions of the AFC are possible: the AFC curve

“rising” or “falling” and AFC “off”.

A practicable VCO alignment of the external coil is the adjustment to zero AFC output current at

pin 22. At the center frequency, the AFC output current is equal to zero. Furthermore, at pin 14,

the VCO center frequency can be switched to set it to the required L’ value (L’ standard).

The optional potentiometer at pin 26 allows an offset compensation of the VCO phase for

improved sound quality (fine adjustment). Without a potentiometer (open circuit at pin 26), this

offset compensation is not active.

The oscillator signal passes a phase shifter and supplies the in-phase signal (0°) and the

quadrature signal (90°) of the generated picture carrier.

4803C–TVVCR–10/05

TDA4470

2.4 Video Demodulation and Amplifier

The video IF signal, which is applied from the gain-controlled IF amplifier, is multiplied with the

in-phase component of the VCO signal. The video demodulator is designed for low distortion

and large bandwidth. The demodulator output signal passes an integrated low-pass filter for

attenuation of the residual vision carrier and is fed to the video amplifier. The video amplifier is

realized by an operational amplifier with internal feedback and 8 MHz bandwidth (–3 dB). A stan-

dard dependent DC level shift in this stage delivers the same synchronous level for positive and

negative modulation. An additional noise clipping is provided. The video signal is fed to the

VIF-AGC and to the video output buffer. This amplifier with a gain of 6 dB offers easy adoption of

the sound trap. For a nominal video IF modulation, the video output signal at pin 12 is 2 VPP.

2.5 Sound IF Amplifier and SIF-AGC

The SIF amplifier is nearly identical with the 3-stage VIF amplifier, except that the first amplifier

stage exists twice and is switchable by a control voltage at pin 3. Therefore, it is possible to

switch between two different SAW filters with minimal external expense. Both SIF inputs fea-

tures excellent cross-talk attenuation and an input impedance which is independent from the

switching condition.

The SIF-AGC is related to the average level of the AM or FM carrier and controls the SIF ampli-

fier to provide a constant SIF signal to the AM demodulator and QPS mixer.

2.6 AM Demodulator

The alignment-free AM demodulator is realized by a synchronous detector. The modulated SIF

signal from the SIF amplifier output is multiplied in phase with the limited SIF signal (AM is

removed). The AF signal of the demodulator output is fed to the output amplifier and to the

SIF-AGC. For all TV standards with negative video modulation (e.g., B/G standard), the AF out-

put signal (pin 25) is switched off by the standard switch.

2.7 Quasi Parallel Sound (QPS) Mixer

The QPS mixer is realized by a multiplier. The SIF signal (FM or NICAM carrier) is converted to

the intercarrier frequency by the regenerated picture carrier (quadrature signal) which is pro-

vided from the VCO. The intercarrier signal is fed via an output amplifier to pin 24.

2.8 Standard Switch

To have equal polarity of the video output signal the polarity can be switched in the demodula-

tion stage in accordance with the TV standard. Additionally a standard dependent DC level shift

in the video amplifier delivers the same sync. level. In parallel to this, the correct VIF-AGC is

selected for positively or negatively modulated VIF signals. In the case of negative modulation

(e.g., B/G standard) the AM output signal is switched off. For positive modulation (L standard)

the AM demodulator and QPS mixer is active. This condition allows a parallel operation of the

AM sound signal and the NICAM-L stereo sound.

2.9 L’ Switch

With a control voltage at pin 14 the VCO frequency can be switched in order to set required L’

value (L’ standard). Also a fine adjustment of the L’-VCO center frequency is possible via a

potentiometer. The L' switch is only active for positively modulated video IF-signals (standard

switch in L mode).

4803C–TVVCR–10/05

TDA4470

2.10 AFC Switch

The AFC output signal at pin 22 can be controlled by a switching voltage at pin 19. It is possible

to select an AFC output signal with a rising- or falling AFC curve and to switch off the AFC.

2.11 VCR Mode

For VCR mode in a TV set (external video source selected), it is recommended to switch off the

IF circuit. With an external switching voltage at pin 6 or 7, the IF amplifiers are switched off and

all signal output levels at pins 12, 24, and 25 are according to the internal DC voltage.

2.12 Internal Voltage Stabilizer

The internal bandgap reference ensures constant performance independent of supply voltage

and temperature.

4803C–TVVCR–10/05

TDA4470

3. Pin Configuration

Figure 3-1. Pinning SO28/SSO28

VI,SIF1

GND

CAGC

VSW

VI,VIF

CAGC

GND

RTOP

ITUN

VO,VID

VSW

VI,SIF2

RCOMP

VO,AM

VO,FM

VAFC

VVCO

VSW

CREF

GND

CBL

VI,SIF1

VI,VIF

VVCO

VI,SIF2

4803C–TVVCR–10/05

TDA4470

Table 3-1. Pin Description

Pin Symbol Function

1, 2 VI,SF1 SIF1 input (symmetrical)

3 VSW Input selector switch

4, 9, 16 GND Ground

5 CAGC SIF-AGC (time constant)

6, 7 VI,VIF VIF input (symmetrical)

8 CAGC VIF-AGC (time constant)

10 RTOP Take-over point, tuner AGC

11 ITUN Tuner AGC output current

12 VO,VID Video output

13 VSW Standard switch

14 VSW L’ switch

15 CBL Black level capacitor

17 CREF Internal reference voltage

18 LF Loop filter

19 VSW AFC switch

20, 21 VVCO VCO circuit

22 VAFC AFC output

23 VS Supply voltage

24 VO,FM Intercarrier output

25 VO,AM AF output - AM sound

26 RCOMP Offset compensation

27, 28 VI,SIF2 SIF 2 input (symmetrical)

4803C–TVVCR–10/05

TDA4470

4. Absolute Maximum Ratings

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating

only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this

specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Reference point pin 4 (9, 16), unless otherwise specified

Parameters Symbol Value Unit

Supply voltage, pin 23

SO28 and SSO28 package VS6.0 V

Supply current, pin 23 IS93 mA

Power dissipation

SO28 and SSO28 package P 560 mW

Output currents, pins 12, 24 and 25 IOUT 5mA

External voltages

Pins 1, 2, 5 to 8, 10, 12, 18 and 24 to 28

Pins 15, 20 and 21

Pin 11

Pins 3, 13, 19 and 22

Vext

+4.5

+3.5

+13.5

Junction temperature Tj+125 °C

Storage temperature Tstg –25 to +125 °C

Electrostatic handling(1), all pins VESD ±300 V

Note: 1. Equivalent to discharging a 200 pF capacitor through a 0Ω resistor.

5. Thermal Resistance

Parameters Symbol Value Unit

Junction ambient, when soldered to PCB

SO28 package

SSO28 package

RthJA

130

K/W

6. Operating Range

Parameters Symbol Value Unit

Supply voltage range, pin 23

SO28 and SSO28 package VS4.5 to 6.0 V

Ambient temperature Tamb –10 to +85 °C

4803C–TVVCR–10/05

TDA4470

7. Electrical Characteristics

VS = +5V, Tamb = +25°C; reference point pin 4 (9, 16), unless otherwise specified.

Parameters Test Conditions Pin Symbol Min. Typ. Max. Unit

DC-supply 23

Supply voltage, SO28, SSO28 VS4.5 5.0 5.5 V

Supply current IS85 93 mA

VIF-input 6-7

Input sensitivity (RMS value) For FPLL locked VIN 80 120 µVRMS

Input impedance (1) RIN 1.2 kΩ

Input capacitance (1) CIN 2pF

VIF-AGC 8 and 15

IF gain control range GV60 65 dB

AGC capacitor 8 CAGC 2.2 µF

Black level capacitor 15 CBL 100 nF

Switching voltage: VCR mode (2) VSW 4.0 V

Switching current: VCR mode (2) ISW 50 µA

Tuner-AGC 10 and 11(3)

Available tuner-AGC current Itun 124mA

Allowable output voltage V11 0.3 13.5 V

IF slip - tuner AGC Current ITUN: 10% to 90% ∆GIF 810dB

IF input signal for minimum

take-over point RTOP = 10 kΩ (VTOP = 4.5V) VIN 4mV

IF input signal for maximum

take-over point RTOP = 0, (VTOP = 0.8V) VIN 40 mV

Variation of the take-over point

by temperature ∆Tamb = 55°C

VIF-AGC: GV = 46 dB ∆VIN 23dB

Notes: 1. This parameter is given as an application information and has not been tested during production.

2. In VCR mode, the VIF- and SIF path is switched off.

3. The adjustment of the turn over point (delayed tuner AGC) with the external resistor RTOP or external voltage VTOP is

possible.

4. Resonance circuit of VCO (fo = 38.9 MHz): CVCO = 8.2 - 10 pF,

Coil LVCO with unloaded Q-factor Qo ≥ 60 for an oscillator voltage ≥ 100 mVRMS at pin 20 - 21

(e.g., TOKO® coil 7 KM, 292 XNS - 4051Z).

5. The oscillator drift is related to the picture carrier frequency, given that the external LC circuit is temperature-compensated.

6. α (1.07) = 20 log (4.43 MHz component/1.07 MHz component); α (1.07) value related to black-white signal

input signal conditions: picture carrier = 0 dB, colour carrier = –6 dB, sound carrier = –24 dB.

7. Without external control at pin 13 the IC automatically operates in mode 1:

⇒ negatively modulated video-IF signals and FM/NICAM sound signals.

8. Without a control voltage at pin 19 the falling AFC curve is automatically selected.

9. With an open circuit at pin 14 the L’ switch is not active.

10. Picture carrier PC = 38.9 MHz; sound carrier SC1 = 33.4 MHz, SC2 = 33.16 MHz;

PC/SC1 =13 dB; PC/SC2 = 20 dB; PC unmodulated (equivalent to synchronous peak level).

11. Sound carrier SC = 32.4 MHz, modulated with fmod = 1 kHz, m = 54%; VIN =10 mV

12. Without a control voltage at pin 3 the SIF input 1 is automatically selected.

4803C–TVVCR–10/05

TDA4470

FPLL and VCO

18, 20,

21 and 26(4)

Maximum oscillator frequency For carrier generation fVCO 70 MHz

Vision carrier capture range fVCO = 38.9 MHz,

CVCO = 8.2 pF ∆fcap ±1.5 ±2 MHz

Oscillator drift (free running) as

function of temperature

(5)

∆Tamb = 55°C,

Cvco = 8.2 pF,

fvco = 38.9 MHz

∆f/∆t–0.3 %

Video Output 12

Output current

- source

- sink ±I12 2

Output resistance (1) Rout 100 Ω

Video output signal Peak-to-peak value VO,VID 1.8 2.0 2.2 Vpp

Difference of the video signals Between B/G and L ∆VO,VID 10 %

Synchronous level VSYNC 1.2 V

Zero carrier level for negative

modulation, ultra white level

V13 = VS

V8 = 3V VDC 3.4 V

Zero carrier level for positive

modulation, ultra black level

V13 = 0

V8 = 3V VDC 1.15 V

Supply voltage influence on the

ultra white and ultra black level ∆V/V1%/V

Video bandwidth (–3 dB) RL ≥ 1 kΩ, CL ≤ 50 pF B 6 8 MHz

Video frequency response over

the AGC range ∆B2.0dB

Differential gain error ∆G25%

7. Electrical Characteristics (Continued)