TDA1302_1 2 Wed Sep 14 13:30:56 1994
Philips Semiconductors |
Preliminary specification |
|
|
Data amplifier and laser supply circuit for
TDA1302T
CD player and read only optical systems
FEATURES
∙Six input buffer amplifiers with low-pass filtering and with virtually no offset
∙HF data amplifier with a high or low gain mode
∙Two built-in equalizers for single or double-speed mode ensuring high performance in both modes
∙Fully automatic laser control including stabilization and
an ON/OFF switch, plus a separate supply (VDDL) for power reduction
∙Adjustable laser bandwidth and laser switch-on current slope
∙Protection circuit to prevent laser damage due to supply voltage dip
∙Optimized interconnectiion between pick-up detector and digital servo processor (TDA1301T)
∙Wide supply voltage range
∙Wide temperature range
∙Low power consumption.
QUICK REFERENCE DATA
GENERAL DESCRIPTION
The TDA1302T is a data amplifier and laser supply circuit for three-beam pick-up detectors applied in a wide range of mechanisms for Compact Disc and read only optical systems. The device contains 6 amplifiers which amplify and filter the focus and radial diode signals and provides an equalized RF signal suitable for single or double speed mode; the mode can be switched by means of the speed control pin. The device can accommodate astigmatic, single foucault and double foucault detectors and can be applied to all N-sub laser/monitor diode units even though the circuit has been optimized for the Philips CDM12 mechanisms and the digital servo controller TDA1301T. After a single initial adjustment the circuit will maintain control over the laser diode current thus resulting in a constant light output power which is independent of ageing. The IC is mounted in a small-outline package to enable it to be mounted close to the laser pick-up unit on the sledge.
SYMBOL |
PARAMETER |
CONDITIONS |
MIN. |
TYP. |
MAX. |
UNIT |
||
|
|
|
|
|
|
|
|
|
VDD |
supply voltage (pin 18) |
|
3.4 |
− |
5.5 |
V |
||
Diode current amplifiers |
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
|
Gdn |
amplification |
|
|
− |
1.55 |
− |
dB |
|
Ios(d) |
diode output offset current |
|
− |
− |
100 |
nA |
||
B |
3 dB bandwidth |
|
Ii(d) = 1.67 μA |
50 |
− |
− |
kHz |
|
RFE amplifier (built-in equalizer) |
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
|
td(eq) |
equalization delay |
fi = 0.3 MHz |
− |
320 |
− |
ns |
||
td(f) |
flatness delay |
|
double-speed |
− |
5 |
− |
ns |
|
Laser supply |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Io(l) |
output current |
|
VDDL = 3 V |
− |
− |
−100 |
mA |
|
ORDERING INFORMATION |
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
|
TYPE NUMBER |
|
|
|
PACKAGE |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
NAME |
|
DESCRIPTION |
|
|
VERSION |
|
|
|
|
|
|||||
TDA1302T |
SO24 |
plastic small outline package; 24 leads; body width 7.5 mm |
SOT137-1 |
|||||
|
|
|
|
|
|
|
|
|
September 1994 |
2 |
|
|
|
|
|
|
|
|
|
|
TDA1302_1 3 Wed Sep 14 13:30:56 1994
Philips Semiconductors |
Preliminary specification |
|
|
Data amplifier and laser supply circuit for
TDA1302T
CD player and read only optical systems
SCHEMATIC DIAGRAM
|
Schematic diagram for CD player. |
|
Fig.1 |
September 1994 |
3 |
TDA1302_1 4 Wed Sep 14 13:30:56 1994
Philips Semiconductors |
Preliminary specification |
|
|
Data amplifier and laser supply circuit for
TDA1302T
CD player and read only optical systems
BLOCK DIAGRAM
Fig.2 Block diagram.
September 1994 |
4 |
|
|
|
|
|
|
|
|
|
|
TDA1302_1 5 Wed Sep 14 13:30:56 1994
Philips Semiconductors |
Preliminary specification |
|
|
Data amplifier and laser supply circuit for
TDA1302T
CD player and read only optical systems
PINNING |
|
|
|
|
SYMBOL |
PIN |
DESCRIPTION |
|
|
O4 |
1 |
output of diode current amplifier 4 |
|
|
O6 |
2 |
output of diode current amplifier 6 |
|
|
O3 |
3 |
output of diode current amplifier 3 |
|
|
O1 |
4 |
output of diode current amplifier 1 |
|
|
O5 |
5 |
output of diode current amplifier 5 |
|
|
O2 |
6 |
output of diode current amplifier 2 |
|
|
LDON |
7 |
control pin for switching the laser |
|
|
|
|
ON and OFF |
|
|
VDDL |
8 |
laser supply voltage |
|
|
RFE |
9 |
equalized output voltage of sum |
|
|
|
|
signal of amplifiers 1 to 4 |
|
|
RF |
10 |
unequalized output |
|
|
HG |
11 |
control pin for gain switch |
|
|
LS |
12 |
control pin for speed switch |
|
|
CL |
13 |
external capacitor |
|
|
ADJ |
14 |
reference input normally |
|
|
|
|
connected to ground via a resistor |
|
|
GND |
15 |
0 V supply; substrate connection |
|
|
|
|
(ground) |
|
|
LO |
16 |
current output to the laser diode |
|
|
MI |
17 |
laser monitor diode input |
|
|
VDD |
18 |
amplifier supply voltage |
|
|
I2 |
19 |
photo detector input 2 (central) |
|
|
I5 |
20 |
photo detector input 5 (satellite) |
|
|
I1 |
21 |
photo detector input 1 (central) |
|
|
I3 |
22 |
photo detector input 3 (central) |
|
|
I6 |
23 |
photo detector input 6 (satellite) |
Fig.3 Pin configuration. |
|
I4 |
24 |
photo detector input 4 (central) |
||
|
September 1994 |
5 |
|
|
|
|
|
|
|
|
|
|
TDA1302_1 6 Wed Sep 14 13:30:56 1994
Philips Semiconductors |
Preliminary specification |
|
|
Data amplifier and laser supply circuit for
TDA1302T
CD player and read only optical systems
FUNCTIONAL DESCRIPTION
The TDA1302T can be divided into two main sections, the laser control circuit and the photo diode signal filter and amplification section.
Laser control circuit
The main function of the laser control circuit is to control the laser diode current in order to achieve a constant light output power which is based on the current of the monitor diode which is continuously monitored. The circuit is built up into three parts.
The first part is the input stage which compares the monitor diode current with a current which is 10 times the value of the adjustable current. The adjustable current is derived from a bandgap reference source, to be temperature independent, and can be further adjusted by the external resistor RADJ in order to adapt the circuit to the parameters of the laser/monitor diode unit to be used. The difference is fed to the second part.
The second part is the integrator stage which makes use of an external capacitor CL. This capacitor has two different functions.
During switch-on of the laser current, it provides a current slope of typically: dILO/dt 10−6/CL (A/s).
After switch-on it ensures that the bandwidth conforms to the typical formula: fB K × Aext × 90−9/(CL × IMON) (Hz).
where Aext represents the AC gain of an extra loop
amplifier, if applied, and K = dImonitor/dIlaser which is determined by the laser/monitor unit.
IMON is the average current (pin 17) at typical light emission power of the laser diode.
Table 1 Operational modes.
The third part is the power output stage, its input being the integrator output signal. This stage has a separate supply voltage (VDDL) thereby offering the possibility of reduced power consumption by supplying this pin with the minimum voltage necessary.
It also has a laser diode protection circuit which is enabled prior to the output drive transistor becoming saturated due to a large voltage dip on VDDL. Saturation will result in a lower current from the laser diode, which is normally followed immediately by an increment of the voltage from the external capacitor CL, which could cause damage to the laser diode at the end of the voltage dip. The protection circuit prevents an increment of the capacitor voltage and thus offers full protection to the laser diode under these circumstances.
Photo diode signal filter and amplification section
This section has 6 identical current amplifiers. Amplifiers 1 to 4 are designed to amplify the focus photo diode signals. Each amplifier has two outputs, an LF output and an internal RF output. Amplifiers 5 and 6 are used for the radial photo diode currents and have only an LF output. All 6 output signals are low-pass filtered with a corner frequency at 65 kHz. The internal RF output signals are summed together and converted into a voltage by means of a selectable transresistance of 120 kΩ or 240 kΩ. This signal is available directly at pin 10, however, there is also an unfiltered signal available at pin 9. The equalization filter used has 2 different filter curves, one for single-speed mode and one for double-speed mode.
|
|
IF NOT |
|
|
|
MODE(1) |
|
|
|
|
SWITCH |
PIN |
CONNECTED |
|
GAIN |
SPEED |
|
LASER |
|||
|
|
DEFAULT |
|
|
|
|
|
|
|
|
|
|
HIGH |
|
LOW |
SINGLE |
DOUBLE |
ON |
|
OFF |
|
|
|
|
|
|
||||||
|
|
|
|
|
|
|
|
|
|
|
|
HG |
1 |
1 |
|
0 |
X |
X |
X |
|
X |
|
|
|
|
|
|
|
|
|
|
|
Control pin |
LS |
1 |
X |
|
X |
1 |
0 |
X |
|
X |
|
|
|
|
|
|
|
|
|
|
|
|
LDON |
1 |
X |
|
X |
X |
X |
1 |
|
0 |
|
|
|
|
|
|
|
|
|
|
|
Note
1. Where X = don’t care.
September 1994 |
6 |
|
|
|
|
|
|
|
|
|
|
TDA1302_1 7 Wed Sep 14 13:30:56 1994
Philips Semiconductors |
Preliminary specification |
|
|
Data amplifier and laser supply circuit for
TDA1302T
CD player and read only optical systems
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
SYMBOL |
PARAMETER |
MIN. |
MAX. |
UNIT |
|
|
|
|
|
VDD |
supply voltage |
- |
8.0 |
V |
Ptot |
total power dissipation |
- |
300 |
mW |
Tstg |
storage temperature |
-65 |
+150 |
°C |
Tamb |
operating ambient temperature |
-40 |
+85 |
°C |
HANDLING
Classification A: human body model; C = 100 pF; R = 1500 W; V = ± 2000 V.
Charge device model: C = 200 pF; L = 2.5 mH; R = 0 W; V = 250 V.
THERMAL RESISTANCE
SYMBOL |
PARAMETER |
THERMAL RESISTANCE |
|
|
|
Rth j-a |
from junction to ambient in free air |
60 K/W |
QUALITY SPECIFICATION
In accordance with “SNW-FQ-611 part E”. The numbers of the quality specification can be found in the “Quality Reference Handbook”. The handbook can be ordered using the code 9398 510 63011.
CHARACTERISTICS
VDD = 3.4 V; VDDL = 2.5 V; Tamb = 25 °C; RADJ = 48 kW; HG = logic 1; LS = logic 1; with an external LP filter (Rext = 750 W, Cext = 47 pF) at pin 9; unless otherwise specified.
SYMBOL |
PARAMETER |
CONDITIONS |
MIN. |
TYP. |
MAX. |
UNIT |
|
|
|
|
|
|
|
Supply |
|
|
|
|
|
|
|
|
|
|
|
|
|
IDD |
amplifier supply current |
laser OFF |
- |
8 |
- |
mA |
VDD |
amplifier supply voltage |
|
3.4 |
- |
5.5 |
V |
VDDL |
laser control supply voltage |
|
2.5 |
- |
5.5 |
V |
Pdiss |
power dissipation |
laser OFF; VDD = 3.4 V |
- |
27 |
- |
mW |
Diode current amplifiers (1 to 6) |
|
|
|
|
|
|
|
|
|
|
|
|
|
Ii(d) |
diode input current |
note 1 |
- |
- |
10 |
mA |
Neq |
equivalent noise input |
|
- |
1 |
- |
pA/ÖHz |
Vi(d) |
diode input voltage |
Ii(d) = 1.67 mA |
- |
0.9 |
- |
V |
Vo(d) |
diode output voltage |
|
-0.2 |
- |
VDD - 1 |
V |
Gdn |
amplification |
Ii(d) = 1.67 mA; |
1.43 |
1.55 |
1.67 |
dB |
|
|
Vo(dn) = 0 V; note 2 |
|
|
|
|
Ios(d) |
diode output offset current |
Icsin = Itsin = 0; note 3 |
- |
- |
100 |
nA |
Zo(d) |
output impedance |
Idi = 1.67 mA; Vo(dn) = 0 V |
500 |
- |
- |
kW |
B |
3 dB bandwidth |
Ii(d) = 1.67 mA |
50 |
68 |
- |
kHz |
Gmm |
mismatch in amplification |
Idi = 1.67 mA; |
- |
- |
3 |
% |
|
|
Vo(dn) = Vo(dm) |
|
|
|
|
September 1994 |
7 |
|
|
|
|
|
|
|
|
|
|
Loading...