Features
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Current-controlled Output Current Source with 5 Input Channels
2 Selectable Outputs for Grounded Laser Diodes
Output Current per Channel up to 200 mA
Total Output Current up to 250 mA
Rise Time 1.0 ns/Fall Time 1.1 ns
On-chip RF Oscillator
Control of 2 Different Frequencies and Swings by Use of 4 External Resistors
Oscillator Frequency Range from 200 MHz to 600 MHz
Oscillator Swing to 100 mA
Single 5-V Power Supply
Common Enable/Disable Input
TTL/CMOS Control Signals
Small SSO24 Package and QFN28 Package
5-Channel Laser
Driver with RF
Oscillator and
2 Outputs
T0800
Applications
•
Combo Drives (DVD + CD-RW)
•
DVD-RAM with CD-RW Capability
•
DVD-RW with CD-RW Capability
1. Description
The T0800 is a laser diode driver for the operation of two different, grounded laser
diodes for DVD-RAM (650 nm) and CD-RW (780 nm). It includes five channels for five
different optical power levels which are controlled by a separate IC. The read channel
generates a continuous output level. The channels 2 to 5 are provided as write chan-
nels with very fast switching speeds. When a
low
signal is applied to the NE pins, write
current pulses are enabled. All channels are summed together and switched to one of
the two outputs IOUTA or IOUTB by the select input SELA. Each channel can contrib-
ute up to 200 mA to the total output current of up to 250 mA. A total gain of 100 is
provided between each reference current input and the selected output. Although the
reference inputs are current inputs, voltage control is possible by using external resis-
tors. An on-chip RF oscillator reduces laser mode hopping noise during read mode.
Frequency and swing can be set independently for the two selectable outputs with two
pairs of resistors. Oscillation is enabled by a
high
signal at the ENOSC pin. Complete
output current and oscillator switch-off is achieved by a
low
signal at the ENABLE
input.
Rev. 4503D–DVD–02/05
2. Pin Configuration
Figure 2-1.
Pinning SSO24
IR
I2
I3
I4
I5
RFA
RFB
NE2
NE3
NE4
NE5
ENABLE
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
VCC1
VCC2
IOUTA
IOUTA
GND
RSA
RSB
IOUTB
IOUTB
SELA
ENOSC
VCC2
Table 2-1.
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16/17
18
19
20
21/22
23
24
Pin Description: SSO24
Symbol
IR
I2
I3
I4
I5
RFA
RFB
NE2
NE3
NE4
NE5
ENABLE
VCC2
ENOSC
SELA
IOUTB
RSB
RSA
GND
IOUTA
VCC2
VCC1
Type
Analog
Analog
Analog
Analog
Analog
Analog
Analog
Digital
Digital
Digital
Digital
Digital
Supply
Digital
Digital
Analog
Analog
Analog
Supply
Analog
Supply
Supply
Function
Input current, bias voltage approximately GND
Input current, bias voltage approximately GND
Input current, bias voltage approximately GND
Input current, bias voltage approximately GND
Input current, bias voltage approximately GND
External resistor to GND sets frequency of oscillator A
External resistor to GND sets frequency of oscillator B
Digital control of channel 2 (low active)
Digital control of channel 3 (low active)
Digital control of channel 4 (low active)
Digital control of channel 5 (low active)
Enables output current (high active)
+5 V power supply for IOUT
Enables RF oscillator (high active)
High: selects IOUTA, RFA, RSA
Low: selects IOUTB, RFB, RSB
Output current source B for laser diode
External resistor to GND sets swing of oscillator B
External resistor to GND sets swing of oscillator A
Ground
Output current source A for laser diode
+5 V power supply for IOUT
+5 V power supply for circuit
2
T0800
4503D–DVD–02/05
T0800
Figure 2-2.
Pinning
QFN28
I3
I2
IR
NC
VCC1
VCC2
VCC2
I4
I5
RFA
RFB
GND
NE2
NE3
1
2
3
4
5
6
7
28 27 26 25 24 23 22
21
20
19
18
17
16
15
8 9 10 11 12 13 14
NE4
NE5
ENABLE
VCC2
VCC2
ENOSC
SELA
IOUTA
IOUTA
GND
RSA
RSB
IOUTB
IOUTB
Table 2-2.
Pin
1
2
3
4
5
6
7
8
9
10
11, 12
13
14
15
16
17
18
19
20
21
22, 23
24
25
26
27
28
Paddle
Pin Description: QFN28
Symbol
I4
I5
RFA
RFB
GND
NE2
NE3
NE4
NE5
ENABLE
VCC2
ENOSC
SELA
IOUTB
IOUTB
RSB
RSA
GND
IOUTA
IOUTA
VCC2
VCC1
NC
IR
I2
I3
–
Type
Analog
Analog
Analog
Analog
Supply
Digital
Digital
Digital
Digital
Digital
Supply
Digital
Digital
Analog
Analog
Analog
Analog
Supply
Analog
Analog
Supply
Supply
–
Analog
Analog
Analog
–
Function
Input current, bias voltage approximately GND
Input current, bias voltage approximately GND
External resistor to GND sets frequency of oscillator A
External resistor to GND sets frequency of oscillator B
Ground
Digital control of channel 2 (low active)
Digital control of channel 3 (low active)
Digital control of channel 4 (low active)
Digital control of channel 5 (low active)
Enables output current (high active)
+5 V power supply IOUT
Enables RF oscillator (high active)
High: selects IOUTA, RFA, RSA
Low: selects IOUTB, RFB, RSB
Output current source B for laser diode
Output current source B for laser diode
External resistor to GND sets swing of oscillator B
External resistor to GND sets swing of oscillator A
Ground
Output current source A for laser diode
Output current source A for laser diode
+5 V power supply IOUT
+5 V power supply circuit
Not connected
Input current, bias voltage approximately GND
Input current, bias voltage approximately GND
Input current, bias voltage approximately GND
Should be connected with ground
3
4503D–DVD–02/05
Figure 2-3.
Block Diagram
I5
NE5
I4
NE4
I3
NE3
Channel 5
Channel 4
Channel 3
IOUTA
IOUTB
Channel 2
I2
NE2
IR
ENABLE
Read channel
ENOSC
RF oscillator
RFA RFB RSA RSB
SELA
4
T0800
4503D–DVD–02/05
T0800
3. Absolute Maximum Ratings
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating
only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Parameter
Supply voltage
Input voltage at IR, I2, I3, I4, I5
Input voltage at NE2, NE3, NE4, NE5, ENOSC
Output voltage
Power dissipation
Junction temperature
Storage temperature range
Notes: 1. R
thJA
≤
115 K/W, T
amb
= 70°C
2. R
thJA
≤
115 K/W, T
amb
= 25°C
Symbol
V
CC
V
IN1
V
IN2
V
OUT
P
tot
T
J
T
stg
Value
-0.5 to +6.0
-0.5 to +0.5
-0.5 to V
CC
+0.5
-0.5 to V
CC
-1
0.7
(1)
to 1
(2)
150
-65 to +125
Unit
V
V
V
V
W
°C
°C
4. Thermal Resistance
Parameter
Junction ambient
Note:
Symbol
R
thJA
Value
(1)
115 (SSO24)
35 (QFN28)
Unit
K/W
K/W
1. Measured with multi-layer test board (JEDEC standard JESD51-7)
5. Recommended Operating Conditions
Parameter
Supply voltage range
Input current
External resistor to GND to set oscillator
frequency
External resistor to GND to set oscillator swing
Operating temperature range
Symbol
V
CC
I
IR
, I
I2
, I
I3
, I
I4
, I
I5
RFA, RFB
RSA, RSB
T
amb
Value
4.5 to 5.5
< 2.5
>3
> 100
0 to +70
Unit
V
mA
kΩ
Ω
°C
5
4503D–DVD–02/05
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