2003 Jun 03
38
Philips Semiconductors
Preliminary specification
High speed advanced analog DVD signal
processor and laser supply
TZA1035HL
11 APPLICATION INFORMATION
11.1
Signal relationships
Simplified relationships between signals are described in
this section. In the simplification, all built-in options for
DVD-ROM are omitted. The variables A
1
to A
3
, A
LFC
and
A
LFR
, are the linear equivalents of bits G
1
to G
3
, G
LFC
and
G
LFR
.
11.1.1
D
ATA PATH
Pins RFP and RFN carry the RF data signals in opposite
phases with respect to each other. This allows an ADC
with a balanced or differential input to be used in the
decoder. Depending on the DC input ranges of the ADC,
in many cases the connection between TZA1035HL and
the decoder can be a DC pin to pin connection. The
common mode DC level of pins RFP and RFN can be
chosen independently by means of input pin RFREF.
If bit RFSUM = 0
V
RFP
= V
RFREF
+ 0.5
×
A
3
×
A
2
×
A
1
×
(V
I
V
RFOFFS
)
V
RFN
= V
RFREF
0.5
×
A
3
×
A
2
×
A
1
×
(V
I
V
RFOFFS
)
V
RFDIF
= A
3
×
A
2
×
A
1
×
(V
I
V
RFOFFS
).
If bit RFSUM = 1
V
RFP
= V
RFREF
+ 0.5
×
A
RFSUM
×
A
3
×
(V
RFSUMP
V
RFSU
MN
V
RFOFFSS
)
V
RFN
= V
RFREF
0.5
×
A
RFSUM
×
A
3
×
(V
RFSUMP
V
RFSU
MN
V
RFOFFSS
)
V
RFDIF
= A
RFSUM
×
A
3
(V
RFSUMP
V
RFSUMN
V
RFOFFSS
).
Where:
A
1
, A
2
, A
3
and A
RFSUM
are programmed gain values
V
I
= averageinputvoltageatpins A to D,withrespectto
the voltage at pin OPUREF
V
RFOFFS
is the programmed RF
OFFS
DAC voltage
(register 4 and register 5)
V
RFREF
is the input voltage at pin RFREF.
Correct settings for V
RFREF
and V
RFOFFS
are required to
keep both V
RFP
and V
RFN
at the DC voltage levels
specified for the TZA1035HL and the decoder.
11.1.2
S
ERVO PATH
The current through output pins OA to OD represents the
low-pass filtered input voltage of each individual pick-up
segment. The gain from input to output can be
programmed to adapt to different disc types or pick-ups
(offset cancellation is omitted for simplicity):
(in DVD push-pull mode)
(in DVD push-pull mode)
or:
(in CD three-beam push-pull mode)
(in CD three-beam push-pull mode)
or
(in DPD mode)
(in DPD mode)
Where:
A
LFC
and A
LFR
are the programmable gains in central
and radial paths
Gain should be programmed such that maximum signal
levels fit into the range of the servo processor ADC
V
I(A)
; V
I(B)
; V
I(C)
and V
I(D)
are defined as input voltages
at pins A to D with respect to pin OPUREF
I
DC
is a DC current that keeps I
S1
and I
S2
unipolar
I
FS
is the sensitivity to relative phase difference.
Phase difference =
;
180
°
<
φ
< + 180
°
.
I
Ox
V
-----14 k
A
×
=
I
S1
V
---------------------------------------A
V
30 k
(
LFR
=
I
S2
V
-----------------------------------------A
V
30 k
(
LFR
=
I
S1
V
-----------------------------
A
×
15 k
=
I
S2
V
-----------------------------
A
×
15 k
=
I
S1
I
DC
I
FS
phase difference
×
+
=
I
S2
I
DC
I
FS
–
phase difference
×
=
t
T
p
-----
360
]
--------- degrees
=