DESCRIPTION
s
Up to 1.25Gb/s operation
s
75mA peak drive current
s
Separate modulation control
s
Separate master reset for laser safety
s
Differential inputs for data and clock
s
75K
input pulldown resistor
s
Single power supply
s
Available in 16-pin SOIC package
The SY100EL1001 is a high speed current source for
driving a semiconductor laser diode in optical transmission
applications. The output current modulation is DC
voltage controlled. The integrated circuit contains the
following functional blocks:
Input Line Receiver
D Flip-Flop
Bias Control Circuitry
Output Current Switch
A logic HIGH level at the data input results in the
modulation current flowing through the OUT pin on the
next rising edge of the clock. A logic HIGH level at the
master reset input will disable the modulation current.
The device incorporates complementary open collector
outputs with a capability of driving peak current of 75
mA.
The laser driver current is adjustable by selection of
R
SET
. The resistor R
EXT
must be placed between OUT
and V
CC
to dissipate the worst case power. R
SER
is
recommended to fix laser diode matching issues.
The SY100EL1001 utilizes the high performance
bipolar ASSET technology.
FEATURES
LASER DIODE DRIVER
WITH INPUT D FLIP-FLOP
PIN CONFIGURATION
PRELIMINARY
SY100EL1001
Rev.: E
Amendment: /0
Issue Date:
August, 1998
BLOCK DIAGRAM
CLK, CLK
D, D
MR
V
CC
R
EXT
OUT
V
BB
R
SET
V
EE
R
SER
to Laser Diode
BIAS
Control
MC
Modulation Control
D Flip-Flop
OUT
NC
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
CLK
CLK
R
SET
V
CCO
D
D
MR
V
CC
NC
MC
OUT
OUT
V
BB
NC
V
EE
Top View
SOIC
Z16-2
1
2
PRELIMINARY
SY100EL1001
Micrel
D
D
CLK
CLK
MR
OUT
OUT
L
H
Z
ZZ
L
H
L
H
L
Z
ZZ
L
L
H
X
X
X
X
H
H
L
NOTE:
1. L = LOW, H = HIGH, Z = LOW-to-HIGH transition,
ZZ = HIGH-to-LOW transition, X = don't care.
Pin
Function
V
CC
, V
CCO
Most positive power supply pins separation helps
to isolate sensitive circuitry from noise
generating function. +5V for PECL operation
or ground for ECL operation.
V
EE
Most negative power supply input. Ground
for PECL operation or -5V for ECL operation.
V
BB
This pin provides a reference voltage for use
in single ended applications or when the
input signal is AC coupled into the device.
D,D
These differential ECL/PECL 100K
compatible inputs receive NRZ data.
CLK, CLK
These differential clock inputs
MR
This ECL/PECL 100K compatible input resets
the Laser Driver Logic - modulation current
transitions to zero when asserted high.
OUT, OUT
Open collector outputs from the modulation
buffer drive these differential current outputs.
MC
An external voltage sets the main value of
modulation current I
O
.
R
SET
An external resistor sets the source current
for modulation I
mod
.
NC
These pins are not connected.
Symbol
Rating
Value
Unit
V
CC
Power Supply Voltage (V
CC
= 0V)
0 to -7.0
V
V
IN
Input Voltage (V
CC
= 0V)
0 to -6.0
V
I
O
Output Current
75
mA
T
A
Operating Temperature Range
-40 to +85
C
P
tot
Power Dissipation
500
mW
ABSOLUTE MAXIMUM RATINGS
(1)
NOTE:
1. Permanent device damage may occur if ABSOLUTE MAXIMUM RATINGS are exceeded. This is a stress rating only and functional operation is not implied
at conditions other than those detailed in the operational sections of this data sheet. Exposure to ABSOLUTE MAXIMUM RATlNG conditions for extended
periods may affect device reliability.
PIN NAMES
TRUTH TABLE
(1)
Symbol
Rating
Value
Unit
V
EE
Power Supply Voltage
-4.75 to -5.25
V
R
SET
Resistor to Adjust Current
10 to 100
R
EXT
Resistor to Dissipate Power
10 to 50
R
SER
Laser Diode Serial Resistor
0 to 50
OPERATIONING CONDITIONS
(1)
NOTE:
1. The voltage drop across R
EXT
and R
SER
should not be greater than 2V.
5
PRELIMINARY
SY100EL1001
Micrel
APPLICATION EXAMPLE
NOTES:
1.
Split 100K ECL terminations are 82
and 130
to V
CC
and V
EE
respectively.
2.
Recommended power supply bypass capacitors are 0.1
F with optional 10
F Tantalum in parallel.
3.
High frequency design techniques are required for board layout. A double sided or multilayer board is recommended in conjunc
tion with a low
impedance ground plane and properly terminated transmission lines for all signal paths.
4.
V
BB
voltage pin may be used as reference for single ended input applications.
V
CC
R
SET
V
EE
V
CCO
D
50
COAX
50
COAX
R
EXT
R
SET
SY100EL1001
V
EE
V
EE
OUT
R
SER
LASER MODULE
INPUTS
50
COAX
LASER BIAS / APC CONTROL
470k
0.1F
0.1F
1k
1k
10k
1k
B
750
47k
47k
4.7k
47k
10k
A
CLK
CLK
OUT
0.02F
V
EE
V
CC
V
CC
V
CC
IC
1
= IC
2
= LM324
V
EE
=
5.0V
V
CC
= 0V
IC
2
+
IC
1
+
0.1H
50
COAX
MR
D
50
COAX
V
CC
V
CC
0.1F
130
82
V
CC
500
24
10
MC
V
CC
V
EE
10k
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