INTEGRATED CIRCUITS
DATA SHEET
TZA1026
Data amplifier and laser supply
circuit for CD audio and video
optical systems (ADALASAuto)
Product specification
File under Integrated Circuits, IC01
1998 Oct 30
Philips Semiconductors
Product specification
Data amplifier and laser supply circuit for CD
audio and video optical systems (ADALASAuto)
FEATURES
•
Suitable for automotive applications
•
Supports a wide range of voltage output mechanisms
•
RF amplifier designed for audio and video applications
with data rates up to a maximum of n = 4 times speed
•
Programmable RF gain for CD-Audio/Video (CD-A/V)
and CD-Read/Write (CD-R/W) discs
•
Adjustable equalizer for n = 1 or n = 2 times speed
•
Fully Automatic Laser Power Control (ALPC) including
stabilization plus a separate laser supply voltage for
power efficiency
•
Adjustable current range of ALPC output
•
Automatic N- or P-substrate monitor diode selection
•
Adjustable laser bandwidth and laser switch-on current
slope using external capacitor
•
Protection circuit to prevent laser damage due to laser
supply voltage dip
•
Optimized interconnection between data amplifier and
Philips’ digital signal processor CD10Auto (SAA7326)
•
Wide supply voltage range
•
Power-down switch to reduce power consumption
during standby
•
Wide temperature range
•
Low power consumption.
GENERAL DESCRIPTION
The TZA1026 is a data amplifier and laser supply circuit for
voltage output mechanisms found in a wide range of audio
and video CD systems. The device contains an RF
amplifier and an automatic laser power control circuit.
The preamplifier forms a versatile, programmable
interface for voltage output CD mechanisms to the Philips’
digital signal processor CD10Auto (SAA7326).
TZA1026
The RF bandwidth allows this device to be used in CD-A/V
and CD-R/W applications with a data rate up to a
maximum of n = 4 times speed. The RF gain can be
adapted for CD-A/V discs or CD-R/W discs by means of
the gain select signal.
The equalizer can be adjusted for n = 1 or n = 2 times
speed with the equalizer/speed select signal. For n = 4
times speed the RF is not equalized.
The TZA1026 can be adapted to a wide range of voltage
output mechanisms by means of external resistors.
The ALPC circuit will maintain control over the laser diode
current. With an on-chip reference voltage generator, a
constant and stabilized output power is ensured
independent of ageing. The ALPC can accommodate
N- or P-substrate monitor diodes.
A separate supply voltage connection for the laser allows
the internal power dissipation to be reduced by connecting
a low voltage supply. The laser output current range can
be optimized to fit the requirements of the laser diode by
means of one external resistor. When a DC-to-DC
converter is used, in combination with the control loop of
the ALPC, the adjustable output current range provides
the possibility to compensate for the extra gain a DC-to-DC
converter introduces in the control loop.
1998 Oct 30
2
Philips Semiconductors
Product specification
Data amplifier and laser supply circuit for CD
audio and video optical systems (ADALASAuto)
QUICK REFERENCE DATA
SYMBOL
Supplies
V
DD
I
DD
V
DD(L)
RF amplifier
t
d(f)(RF)
RF flatness delay
EQSEL = LOW; n = 1
EQSEL = HIGH; n = 2
EQSEL = open-circuit;
n = 4; non equalized
Laser supply circuit
I
o(LASER)(max)
maximum laser output current
V
i(mon)
monitor input voltage
N-substrate monitor diode
P-substrate monitor diode
Temperature range
T
oper
operating temperature
−40
−
−
−
0.150
V
DD
−
0.150
V
DD(L)
−
V
o(LASER)
= 0.55 V 80
−
−
−
−
−
−
−
supply voltage
supply current
laser supply voltage
2.7
−
2.7
−
3
−
PARAMETER
CONDITIONS
MIN.
TYP.
TZA1026
MAX.
UNIT
5.5
−
5.5
V
mA
V
10
5
2.5
ns
ns
ns
−
−
−
mA
V
V
°C
+85
ORDERING INFORMATION
TYPE
NUMBER
TZA1026T
PACKAGE
NAME
SO14
DESCRIPTION
plastic small outline package; 14 leads; body width 3.9 mm
VERSION
SOT108-1
1998 Oct 30
3
Philips Semiconductors
Product specification
Data amplifier and laser supply circuit for CD
audio and video optical systems (ADALASAuto)
BLOCK DIAGRAM
TZA1026
handbook, full pagewidth
VDD
13
VDD
1×
CDRW
11
12
EQSEL
9
DIN
5
4×
10
RFFB
RFEQO
2×
8
250
kHz
CMFB
TZA1026
V/I
MON
4
(1)
1
LD
VGAP
V/I
14
3
VDD
6
GND
2
MBK889
RGADJ
CFIL
PWRON
7
VDD(L)
(1) Band gap reference voltage.
Fig.1 Block diagram.
1998 Oct 30
4
Philips Semiconductors
Product specification
Data amplifier and laser supply circuit for CD
audio and video optical systems (ADALASAuto)
PINNING
SYMBOL
LD
V
DD(L)
CFIL
MON
DIN
GND
PWRON
CMFB
RFFB
RFEQO
CDRW
EQSEL
V
DD
RGADJ
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
DESCRIPTION
current output to laser diode
laser supply voltage
external filter capacitor
laser monitor diode input
central diode input
ground
power-on select input
common mode feedback voltage
input
external RF feedback resistor
RF amplifier output
gain select input for CD-A/V, CD-R/W
equalizer/speed select input
(n = 1, 2 or 4)
supply voltage
external laser supply gain adjust
resistor
TZA1026
The gain of the RF amplifier can be adjusted by the
external input resistors. Fig.3 shows the simplified
schematic which can be used to determine the RF gain.
The signal is AC coupled to the RF amplifier. The formula
to determine the gain is shown below:
Z
tr
(
RF
)
G
RF
= –
n
×
------------------
(1)
R2
where:
G
RF
is the RF amplifier gain
n is the number of input resistors
Z
tr(RF)
is the transimpedance of the amplifier (Ω)
R2 is the value of the input resistors(Ω).
The gain can be increased by a factor 4 by making
pin CDRW HIGH. The value of Z
tr(RF)
is 9.8 kΩ for CD-A/V
(CDRW = LOW) and 38 kΩ for CD-R/W (CDRW = HIGH).
The equalizer/bandwidth section can be switched between
n = 1, n = 2 (inclusive the corresponding equalizer) or
n = 4 (inclusive the required bandwidth limitation) times
speed.
The DC output level of the amplifier can be set by applying
a DC voltage on the common mode feedback pin CMFB.
Since the input signal is AC-coupled the RF output voltage
will swing (symmetrically) around this DC level.
The coupling of the TZA1026 to the signal processor
(SAA7326) can be either AC or DC. When an AC-coupling
is chosen (see Fig.8) the minimum supply voltage can be
applied. When a DC-coupling is chosen (see Fig.9) a
minimum supply voltage of 2.8 V is required.
handbook, halfpage
LD 1
VDD(L) 2
CFIL 3
MON 4
DIN 5
GND 6
PWRON 7
MBK890
14 RGADJ
13 VDD
12 EQSEL
TZA1026
11 CDRW
10 RFEQO
9
RFFB
8 CMFB
Fig.2 Pin configuration.
handbook, halfpage
Vin
R2(1)
R2(2)
C2
10 kΩ
Vin
RFEQO
FUNCTIONAL DESCRIPTION
The TZA1026 consists of two sections, the RF amplifier
and the automatic laser power control circuit.
RF amplifier
The RF amplifier consists of a current input amplifier, an
equalizer/bandwidth section and a transimpedance output
amplifier with an external feedback resistor of 10 kΩ (fixed
value).
1998 Oct 30
5
Vin
R2(n)
CDRW
MGL530
Fig.3 Simplified schematic.
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