TEA5750 ACTIVE SIDEBAND OPTIMIZATION (ASOplus)
. .. . .. .
ADVANCE DATA
VHS, S-VHS, VIDEO 8, HI-8 VCR APPLICATIONS PICTURE SHARPNESS IMPROVEMENT S/N RATIO IMPROVEMENT WHEN PLAYING BACK AGED TAPES REDUCTION OF THE DISTURBING TEARING EFFECTS SMALL DETAILS ENHANCEMENT ADJUSTMENT FREE 5V POWER SUPPLY
SO14 (Plastic Package)
DESCRIPTION
ORDER CODE : TEA5750
The TEA5750 IC improves the picture sharpness by active correction of the phase of the FM playback signal. It also allows the optimization of the S/N ratio by autoadaptativebandwidthadjustment. For further information please refer to the Application Note AN551. PIN CONNECTIONS
1
14
I REF
HYSTLVL
2
13
GAIN CTRL
OUT1
3
12
ERR-MEM
ERR-DET
4
11
IN1
PHSHIFT
5
10
VDD
GND
6
9
OUT2
IN2
7
8
TO BE CONNECTED TO GND 5750-01.EPS
SOFTSW
February 1993 This is advance information on a new product now in development or undergoing evaluation. Details are subject to change without no tice.
1/14
TEA5750 BLOCK DIAGRAM
I R E F GAIN CTRL ERR-MEM
IN1
VD D
14
11
10
13
12
TO BE CONNECTED OUT2 TO GND 9 8
BIAS INPU T AMP
A1
ERROR DETECTOR
B A2
SOFTSWITCH
2
3
SOFTSW HYSTLVL
OUT1
4
ERR-DET PHSHIFT
FUNCTIONAL DESCRIPTION Located between the head amplifier and the FM demodulator, the TEA5750, which replaces the commonly used FM equalizer, features the two main following functions : – Dynamic compensation of the phase errors induced in the FM playback signal (errors coming from the limited bandwidth of the front end part of the playback channel : tape, heads rotary transformer, head amplifiers). This compensation improves the fall and rise times of the demodulated signal, and therefore improves the picture sharpness. In the particular case of VHS, TEA5750 leads to flat frequency response of the demodulated signal in excess of 3MHz (Figure 1)
lower sideband
7
GND
IN2
Level with Active Phase Shift 4 3 2
Standard
1 0
1MHz
3MHz Freq.
Figure 2 : Demodulated Signal Bandwidth Adjustment versus Input Signal Quality
upper sideband
3.8MHz sync.
Demodulated Signal
-20
2MHz
– Monitoring of the overall quality of the FM playback signal. In doing so, the TEA5750 automatically and continuously adapts the frequency response of the FM playback signal delivered to the FM demodulator in such a way that the S/N ratio is improved. This function is particularly active in case of aged tapes (Figure 2).
0 -10
6
Figure 1b : Frequency Response of the Demodulated Video Signal (VHS case)
Figure 1a : Spectrum of the Playback FM Carrier (VHS case) dBm
5
5750-04.EPS
1
5750-02.EPS
OUT. AMP
(VH S case)
with active phase shift
-30 -40
-70 1.00MHz/div
REF 5.00MHz
5750-03.EPS
without active phase shift -60
FM signal quality
1
2
3
f (MHz)
Important remark : Unlike FM equalizer solution, the active side band optimization (ASO) performed by the TEA5750 does not trade off picture sharpness against noise sensitivity. 2/14
5750-05.EPS
decreasing
-50
TEA5750 ACTIVE PHASE SHIFTING (phase errors compensation)
input frequency decreases.
The amplitude of the signal delivered by the heads changes with the frequency (amplitude decreases when frequency increases). In combination with an external LC filter the TEA5750 transforms this natural amplitude modulation into phase shifting which compensates the delays (or phase errors) induced during the fast frequency deviations.
Black to White Transients (fast increases of the FM carrier frequency) (Figure 4a) In thiscase, the input FM signal changes from large amplitude and long period to small amplitude and short period. Consequently the delay produced by the phaseshifting circuit changes from large values to small values. At the instance of a black to white transient, the phase shifting induces a long period t0 followed by a short periof t1. This results in a faster frequency shift and in shorter rise times at the output of the FM demodulator.
Phase Shift Generation The core of the phase shifting function is given in Figure 3. Under normal conditions, the VPS voltage at the phase shift input reaches the threshold of the level controlled diodes. Then for each half cycle, as long as the diodes conduct, a magnetic flux is stored in the inductance L. At the phase shift input pin, the next zero crossing time is delayed respect to the input signal VIN for a duration θ which is proportional to the energy WL stored in the inductance L. The energy WL increases versus input amplitude and period, consequently θ increases when the
White to Black Transients (fast decreases of the FM carrier frequency) (Figure 4b) In this opposite case, the input FM signal changes from small amplitudes and short periods to large amplitudes and long periods. The corresponding delays will encrease. So during white to black transient, the period t1 will be increased respect to the input periodtH. This results in a faster frequency change and shorter fall times at the output of the FM demodulator.
Figure 3 : Phase Shift Function Core
From Head Amplifier
L
To FM demodulator
C
VIN VP S
VIN
VP S
11
IC
V PS 3
5
t 7
4
i
AMP
θ
u
Flux in L
threshold control
t
3/14
5750-06.EPS
VIN
4/14
5750-07.EPS
t0
t0 1 t1
t1
θ1
tH
1 tH
θ0
a) Black to white transient
t2
θ2
emphasis
t0
1 tH
t1
tH
1 t1
θ0
tH’
b) White to black transient
t2
θ1
emphasis
1 tH’
1 t2
θ2
Phase shift input voltage VPS
Actual FM playback signal (output from heads)
Record amplifier input signal
Original luma signal
TEA5750 Figure 4 : Phase Shift Effect on the FM Playback Signal
TEA5750 PLAYBACK SIGNAL QUALITY MONITORING (see Figure 5) The TEA5750 monitors the average quality of the playback signal by counting the occurrence rate of missing zero crossing. This phenomena can be noticed in the following cases : – weak and noisy playback signal – poor quality tape At each missing zero crossing in the FM signal, the error memory function of the TEA5750 charges the CMEM capacitorwith a fixed amount of charges (typ. 40µA x 800µs). Then the resulting voltage VMEM at Pin 12 proportionnaly encreases with the error rate. Three operating cases can be distinguished
(see Figure 6). – VMEN < 0.8V : Low error rate, the FM playback signal is good quality. No correction is implemented. – 0.8V ≤ VMEN ≤ 1.2V : The FM playback signal is poor quality and the softswitch is graduallyturned on, modifying then the correcting filter characteristics. The demodulated signal bandwidth is reduced in its upper part (≥ 2.5MHz). – 1.2V < VMEM : The FM signal is very poor quality. The softswitch keeps conducting but additionnally the active phase shifting is reduced by encreasing the clamping threshold of the diodes. This induces a further video bandwidth reduction.
Figure 5 : Average Quality Monitoring of the Playback Signal L
C
CORRECTING FILTER
From Head Amplifier
11
To FM Demodulator
SOFT SWITCH 3
5
Errors
1
7
Q
9 t
AMP VMEM ERROR DETECTOR
ERROR MEM
12
t
C MEM
5750-08.EPS
VMEM
Figure 6 : Video Bandwidth Correction versus FM Signal Quality Demodulated Signal
full bandwidth
encreasing VMEM F(MHz)
1st step Softswitch action
2
3 2nd step Diode threshold modulation effect
5750-09.EPS
1
5/14
TEA5750
Symbol VDD Toper Tj
Parameter Power Supply Voltage Operating Temperature Junction Temperature
Value 6 0, +70 +150
Unit V o C o C
Value 160
o
5750-01.TBL
ABSOLUTE MAXIMUM RATINGS
Symbol Rth (j-a)
Parameter Junction-ambient Thermal Resistance
Max.
Unit C/W
5750-02.TBL
THERMAL DATA
RECOMMENDED OPERATING CONDITIONS Parameter
Min. 4.5
Power Supply Voltage Biasing Resistor Hysteresis Adjustment Error Detector Adjustment
Typ. Max. 5 5.5 1kΩ at 1% 10
1.2
Unit V kΩ V
5750-03.TBL
Symbol VDD R1 R7 V4
ELECTRICAL OPERATING CHARACTERISTICS 5V ± 10% and 0oC < Tamb < 70oC unless otherwise specified Symbol IDD VREF
Parameter Supply Current Reference Voltage
Test Conditions
Min. 1.16
Typ. Max. 24 1.23 1.28
Unit mA V
INPUT AMPLIFIER RIN1 ROUT1 CIN1 G1
dG1 BW1 AC1 IIN1PP IOUT1PP
Input Impedance Output Impedance Input Capacitor Current to Voltage Gain
Gain Dispersion Bandwidth (-3dB) Max. Output Voltage Swing Input Current Capability Output Current Capability
28 17 3 Adjusted by external resistor at Pin 13 R 2 = 1kΩ R 2 = 2kΩ R 2 = 3kΩ R 2 = 1kΩ or R2 = 2kΩ or R2 = 3kΩ 0dB at f = 4.3MHz, RLoad = ∞ Linearity < 1% Linearity < 1%
50 30 5
2.1 3.8 5.2 0 12 3 1 1.5
1 15
Ω Ω pF V/mA V/mA V/mA dB MHz VPP mAPP mAPP
OUTPUT AMPLIFIER RIN2 ROUT2 CIN2 G2 BW2 IIN2PP IOUT2PP
Input Impedance Output Impedance Input Capacitor Open Loop Current to Voltage Gain Bandwidth (-3dB) Input Current Capability Linearity < 1% Output Current Capability Linearity < 1%
700 12 1.5 1
13 25 30 60 3 5 1000 1300 15
Ω Ω pF V/mA MHz mAPP mAPP
VTH ILeak ∆Q
6/14
Threshold Voltage Leakage Current at Pin 12 Injected Charge Unit per detected error from Pin 12
0.95
1 32
1.05 200
V nA nC
5750-04.TBL
ERROR MEMORY
TEA5750 ELECTRICAL OPERATING CHARACTERISTICS 5V ± 10% and 0oC < Tamb < 70oC unless otherwise specified Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
3 0.34 0.9 2.0
5
Unit
PHASE SHIFTER IPHSHIFT Current Capability CIPHSHIFT Capacitance at Pin 5 VCLAMP1 Peak-to-peak Clamp Level at Pin 5 VCLAMP2 VCLAMP3
1 V12 < VTH, I5 = 1mAPP V12 = 1.5V, I5 = 500µAPP V12 = 2.5V, I5 = 500µAPP
mAPP pF V V V
ERROR DETECTOR ∆V ILeak1 VE3 VE4
Hysteresis Voltage R2 = 1kΩ Leakage Current at Pin 4 3T Detection Threshold Voltage at Pin 4 (see Note 1) 4T Detection Threshold Voltage at Pin 4 (see Note 2)
20 200 2.7 3.7
mVPP nA V V
VSF1
Voltage at Pin 12
VSF2
Voltage at Pin 12
To get input impedance at Pin 1 lower than 100Ω To get input impedance at Pin 1 higher than 1kΩ
1.6
V
0.8
V
5750-05.TBL
SOFTSW ITCH
Notes : 1. VE3: Voltage to be applied at Pin 4 to detect 3T long duration without zero crossing. 3T : Three times the average duration between zero crossings of the FM signal (ex: 3 x 116ns in case of VHS). 2. Same as note 1, but in case of four times the average duration between zero crossings of the FM signal.
INPUT/OUTPUT EQUIVALENT INTERNAL CIRCUITS Pin No
Name
Equivalent Circuit
Description
V DD 1
Low-pass filter switch, RDS ON value versus V12 (see Figure 7)
SOFTSW 5750-10.EPS
1
VDD
Error detection hysteresis level adjustment REXT (max.) = 10kΩ
HYSTLVL
2 5750-06.TBL
10kΩ
5750-11.EPS
2
7/14
TEA5750 INPUT/OUTPUT EQUIVALENT INTERNAL CIRCUITS (continued) Pin o N
Name
Equivalent Circuit
Description V DD
3
OUT1
Input amplifier output V3(DC) = 2.25V, V3 P-P (AC) (max.) = 3V
8kΩ
5750-12.EPS
3
•
V DD 4
8kΩ
Voltage Reference for error detection threshold 2V ≤ V4 typ. ≤ 4V
ERR-DET
5750-13.EPS
4
VDD
10kΩ
5
6
GND
Phase shifter (see Figure 7)
8/14
Ground
5750-07.TBL
PHSHIFT
5750-14.EPS
5
TEA5750 INPUT/OUTPUT EQUIVALENT INTERNAL CIRCUITS (continued) Pin o N
Name
Equivalent Circuit
10kΩ
7 IN2
Output amplifier input 5750-15.EPS
7
Description
8
To be connected to ground
10kΩ
9
OUT2
10
VDD
Output amplifier output V9(DC) = 2VBE, V9 P-P (AC) (max.) = 0.75V
5750-08.TBL
5750-16.EPS
9
Power Supply
9/14
TEA5750 INPUT/OUTPUT EQUIVALENT INTERNAL CIRCUITS (continued) Pin o N
Name
Equivalent Circuit
Description VDD
11
IN1
Input amplifier input V11(DC) = 2VBE
V DD
5750-17.EPS
11
VDD
12
ERR-MEM
Error rate store
10/14
5750-09.TBL
5750-18.EPS
12
TEA5750 INPUT/OUTPUT EQUIVALENT INTERNAL CIRCUITS (continued) Pin o N
Name
Equivalent Circuit
Description
V DD
13
Input amplifier gain control 1kΩ ≤ R 13 EXT ≤ 3kΩ
CTRLGAIN
13 4kΩ
5750-19.EPS
4kΩ
5kΩ
Current reference R14 EXT = 1.1kΩ, VDC = 1.23V
IREF 10pF
14
5750-10.TBL
10kΩ
5750-20.EPS
14
11/14
TEA5750 Figure 7 : RDS ON versus VERR-MEM on Pin 12 R DS ON (Ω) V 1 min - t min
200
1
V G = V 12 V 1 min - t max
180
R DS ON
t min = 0°C t max = 100°C
160 140 120 100 80
V 1 max - t min
60
V 1 max - t max
40 20 0 0.5
1
1.5
2
2.5
3
3.5
5750-21.EPS
V 12
Figure 8 : Clamp Voltage versus VERR-MEM on Pin 12 V5PP Clamp Level 4
2
< VCLAMP3
1
< VCLAMP2
0.34 V 12 1
12/14
2
3
4
5
5750-22.EPS
3
TEA5750 TYPICAL APPLICATION DIAGRAM Error memory
R3 1MΩ
C1 1 µF
fi lter
Input from H-Amps
Input stage gain control
Input filter R4 330Ω
R2 2kΩ 1%
R1 1.1kΩ 1% 14
V CC
12
11
10n F
100nF
C2 82pF 13
C10
C3
Output to FM demodulator
10
9
8 C4 10nF
BIAS
INPUT AMP A1
L1 120µH
ERROR
Output
DETECTOR
Error detector
Amp Feedback
adjustment SOFT SWITCH
V DD
OUTPUT AMP A2
1
R5 22kΩ
2
3
4
5
6
7
C6
R6 27kΩ
R7 1kΩ
L2 47 µF
C8
L3 47µF
220pF
10nF
ASO plus main filter
bandwidth correction
C9
Permanent correcting
100pF
R9 820 Ω
R10 2.7kΩ 5750-23.EPS
C5 Video
C7 39pF
filter
13/14
TEA5750 PACKAGE MECHANICAL DATA 14 PINS - PLASTIC MICROPACKAGE L
G
s
e3
b1
e
a1
b
A
a2
C
c1
E
D M
8
1
7
Dimensions
Millimeters Typ.
0.1 0.35 0.19
Max. 1.75 0.2 1.6 0.46 0.25
Min.
Inches Typ.
0.004 0.014 0.007
0.5
Max. 0.069 0.008 0.063 0.018 0.010
0.020 o
45 (typ.) 8.55 5.8
8.75 6.2
0.336 0.228
1.27 7.62 3.8 4.6 0.5
0.344 0.244 0.050 0.300
4.0 5.3 1.27 0.68
0.150 0.181 0.020
0.157 0.208 0.050 0.027
o
8 (max.)
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No licence is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. 1994 SGS-THOMSON Microelectronics - All Rights Reserved Purchase of I2C Components of SGS-THOMSON Microelectronics, conveys a license under the Philips I2C Patent. Rights to use these components in a I2C system, is granted provided that the system conforms to the I2C Standard Specifications as defined by Philips. SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. ASOplus is a trademark of NOKIA CONSUMER ELECTRONICS
14/14
SO14.TBL
A a1 a2 b b1 C c1 D E e e3 F G L M S
Min.
PM-SO14.EPS
F
14
