TDA9885_TDA9886_3 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 03 — 16 December 2008 34 of 56
NXP Semiconductors
TDA9885; TDA9886
I
2
C-bus controlled multistandard alignment-free IF-PLL demodulators
[9] Measurements taken with SAW filter M1963M (sound shelf: 20 dB); loop bandwidth BL = 70 kHz. Modulation VSB; sound carrier off;
f
video
> 0.5 MHz.
[10] Measurements taken with SAW filter M1963M (sound shelf: 20 dB); loop bandwidth BL = 70 kHz. Sound carrier on;
f
video
= 10 kHz to 10 MHz.
[11] AC load; C
L
< 20 pF and R
L
>1kΩ. The sound carrier frequencies (depending on TV standard) are attenuated by the integrated sound
carrier traps (see Figure 15 to Figure 20; H (s) is the absolute value of transfer function).
[12] The sound carrier trap can be bypassed by switching the I
2
C-bus. In this way the full composite video spectrum appears at pin CVBS.
The amplitude is 1.1 V (p-p).
[13] If selected by the I
2
C-bus, the VIF-AGC voltage can be monitored at pin OP2, and pin OP1 can be used as input. In this case, both pins
cannot be used for the normal port function.
[14] The response time is valid for a VIF input level range from 200 µVto70mV.
[15] To match the AFC output signal to different tuning systems a current output is provided. The test circuit is given in Figure 12. The AFC
slope (voltage per frequency) can be changed by resistors R1 and R2.
[16] The tolerance of the reference frequency determines the accuracy of the VIF AFC, FM demodulator center frequency and maximum
FM deviation.
[17] The intercarrier output signal at pin SIOMAD can be calculated by the following formula taking into account the internal video signal with
1.1 V (p-p) as a reference: and , where: is the
correction term for RMS value, is the sound-to-picture carrier ratio at pins VIF1 and VIF2 in dB, 6 dB is the correction term
of internal circuitry and ±3 dB is the tolerance of video output and intercarrier output V
o(intc)(rms)
.
[18] For normal operation (with the I
2
C-bus) no DC load at pin SIOMAD is allowed. The second module address (MAD2) will be activated by
the application of a 2.2 kΩ resistor between pin SIOMAD and ground. If this MAD2 is activated, also the power-on set-up state activates
a VIF frequency of 58.75 MHz.
[19] SIF input level is 10 mV (RMS); VIF input level is 10 mV (RMS) unmodulated.
[20] Measured with an FM deviation of 25 kHz and the typical AF output voltage of 500 mV (RMS). The AF output signal can be attenuated
by 6 dB to 250 mV (RMS) via the I
2
C-bus. For handling a frequency deviation of more than 55 kHz, the AF output signal has to be
reduced in order to avoid clipping (THD < 1.5 %).
[21] The lower limit of the audio bandwidth depends on the value of the capacitor at pin AFD. A value of C
AF
= 470 nF leads to
f
AF(−3dB)
≈ 20 Hz and C
AF
= 220 nF leads to f
AF(−3dB)
≈ 40 Hz.
[22] For all S/N measurements the VIF modulator in use has to meet the following specifications:
a) Incidental phase modulation for black-to-white jump less than 0.5 degrees
b) QSS AF performance, measured with the television demodulator AMF2 (audio output, weighted S/N ratio) better than 60 dB (at
deviation 27 kHz) for 6 kHz sine wave black-to-white video modulation
c) Picture-to-sound carrier ratio PC / SC
1
= 13 dB (transmitter)
[23] Calculation of the loop filter parameters can be done approximately using the following formulae:
BL
−3dB
= f
o
(1.55 −ϑ
2
). The formulae are only valid under the following conditions: ϑ≤1 and C
S
>5C
P
, where:
K
O
is the VCO steepness or K
D
is the phase detector steepness R is the loop resistor; C
S
is the series
capacitor; C
P
is the parallel capacitor; f
o
is the natural frequency of the PLL; BL
−3dB
is the loop bandwidth for −3 dB; ϑ is the damping
factor. For examples, see Table 21.
[24] Window width of digital acquisition help ≤ 237.5 kHz.
[25] The PC / SC ratio is calculated as the addition of TV transmitter PC / SC
1
ratio and SAW filter PC / SC
1
ratio. This PC / SC ratio is
necessary to achieve the S/N
W
values as noted. A different PC / SC ratio will change these values.
[26] Measurements taken with SAW filter G1984 (Siemens) for vision and sound IF (sound shelf: 14 dB). Picture-to-sound carrier ratio of
transmitter PC / SC = 13 dB. Input level on pins VIF1 and VIF2 of V
i(SIF)
= 10 mV (RMS) sync level, 27 kHz FM deviation for sound
carrier, f
AF
= 400 Hz. Measurements in accordance with
“ITU-R BS.468-4”
. De-emphasis is 50 µs.
[27] The QSS signal output on pin SIOMAD is analyzed by a test demodulator TDA9820. The S/N ratio of this device is more than 60 dB,
related to a deviation of ±27 kHz, in accordance with
“ITU-R BS.468-4”
.
V
o(intc)(rms)
1.1
1
22
----------
× 10
r
× V= r
1
20
------
V
iSC()
V
iPC()
----------------
dB()6dB 3dB±+
×=
1
22
----------
V
iSC()
V
iPC()
----------------
dB()
o
1
2π
------
K
O
K
D
C
P
----------------
;=
ϑ
1
2R K
O
K
D
C
P
-----------------------------------
;=
rad
V
---------
2π
Hz
V
-------
;
µA
rad
---------
;
