VITESSE
SEMICONDUCTOR CORPORATION
G52203-0, Rev 3.0
Page 1
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Features
Applications
General Description
The VSC7923 is a single 5V supply, 2.4 Gb/s laser diode driver with direct access to the laser modulation and
bias FET’s. Laser bias and modulation currents are set by external components allowing precision monitoring
and setting of the current levels. Data inputs accept ECL levels. Data density outputs are provided to allow the
user to adjust the laser bias in high unbalanced data applications.
VSC7923 Block Diagram
• Rise Times Less Than 100ps
• High Speed Operation (Up to 2.4Gb/s NRZ Data)
• Single-Ended or Differential Input Operation
• Single Power Supply
• Direct Access to Modulation and Bias FETs
• Data Density Monitors
• SONET/SDH at 622Mb/s, 1.244Gb/s,
2.488Gb/s, 3.125Gb/s
• Full-Speed Fibre Channel (1.062Gb/s)
DIN
VREF
MK
NMK
IBIAS
NIOUT
IOUT
VIP
VIB
MIP
MIB
IMOD
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Page 2
G52203-0, Rev 3.0
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Table 1: Signal Pin Reference
Table 2: Absolute Maximum Ratings
Table 3: Recommended Operating Conditions
NOTES: (1) Lower limit of specification is ambient temperature and upper limit is case temperature. (2) See section “Calculation of the
Maximum Case Temperature” for detailed maximum temperature calculations.
Table 4: ECL Input and Outputs
Signal
Type
Level
# Pins
Description
DIN
In
ECL
1
Data Input
MK, NMK
Out
ECL
2
Data Density Differential Outputs
NIOUT
Out
1
Laser Modulation Current Output (Complementary)
IOUT
Out
1
Laser Modulation Current Output (To Laser Cathode))
VSS
Pwr
Pwr
5
Negative Voltage Rail
GND
Pwr
Pwr
9
Positive Voltage Rail
VIP
In
DC
1
Modulation Gate Node
MIP
In
DC
1
Modulation Source Node
VIB
In
DC
1
Bias Gate Node
MIB
In
DC
1
Bias Source Node
VREF
In
DC
1
Data Input Reference
Total Pins
24
Symbol
Rating
Limit
V
SS
Negative Power Supply Voltage
V
CC
to -6.0V
T
J
Maximum Junction Temperature
-55°C to + 125°C
T
STG
Storage Temperature
-65°C to +150°C
Symbol
Parameter
Min
Typ
Max
Units
Conditions
GND
Positive Voltage Rail
—
0
—
V
VSS
Negative Voltage Rail
-5.5
-5.2
-4.9
V
T
Cl
Operational Temperature
(1)
-40
—
85
(2)
°C
Power dissipation = 1.25W
T
J
Junction Temperature
—
—
125
°C
Symbol
Parameter
Min
Typ
Max
Units
Conditions
V
IN
Input Voltage Swing
300
—
800
mV
Peak-to-peak, V
REF
= -2.0V
V
OH
ECL Output High Voltage
-1200
—
—
mV
50
Ω
to -2.0V
V
OL
ECL Output Low Voltage
—
—
-1600
mV
50
Ω
to -2.0V
VITESSE
SEMICONDUCTOR CORPORATION
G52203-0, Rev 3.0
Page 3
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Table 5: Power Dissipation
Table 6: Laser Driver DC Electrical Specifications
Table 7: Laser Driver AC Electrical Specifications
Table 8: Package Thermal Specifications
Symbol
Parameter
Min
Typ
Max
Units
Conditions
I
VSS
Power Supply Current (VSS)
—
—
220
mA
V
SS
= -5.5V, I
MOD
= I
BIAS
= 0mA
P
D
Total Power Dissipation
—
—
1210
mW
V
SS
= -5.5V, I
MOD
= I
BIAS
= 0mA,
R
LOAD
= 25
Ω
to GND
P
DMAX
Maximum Power Dissipation
—
—
1815
mW
V
SS
= -5.5V, I
MOD
= 60mA,
I
BIAS
= 50mA, I
OUT
= 0V
Symbol
Parameter
Min
Typ
Max
Units
Conditions
I
BIAS
Programmable Laser Bias Current
2
—
50
mA
—
I
MOD
Programmable Modulation Current
2
—
60
mA
—
V
IB
Laser Bias Control Voltage
—
—
V
SS
+
2.1
V
I
BIAS
= 50mA
V
IP
Laser Modulation Control Voltage
—
—
V
SS
+
2.1
V
I
MOD
= 60mA
V
OCM
Output Voltage Compliance
GND -
2.2V
—
—
V
V
SS
= -5.2V
Symbol
Parameter
Min
Typ
Max
Units
Conditions
t
R
, t
F
Output Rise and Fall Times
—
—
100
ps
25
Ω
load, 20%-80%,
15mA < I
MOD
< 60mA,
I
BIAS
= 20mA
Symbol
Parameter
Min
Typ
Max
Units
Conditions
θ
JCC
Thermal Resistance from Junction-to-Case
—
25
—
°C/W
Ceramic Package
θ
JCMG
Thermal Resistance from Junction-to-Case
—
32
—
°C/W
Metal Glass Package
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Page 4
G52203-0, Rev 3.0
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Calculation of the Maximum Case Temperature
The VSC7923 is designed to operate with a maximum junction temperature of 125°C. The rise from the case to
junction is determined by the power dissipation of the device. The power dissipation is determined by the V
SS
current plus the operating I
MOD
and I
BIAS
currents.
The power of the chip is determined by the following formula:
P
D
=(-VSS * I
SS
) + ((V
IOUT
– V
SS
) * I
MOD
) + ((V
IBIAS
– V
SS
) * I
BIAS
)
For example with:
V
SS
= -5.2V
I
MOD
= 40mA
I
BIAS
= 20mA
V
IBIAS
= -2.0V
V
IOUT
= -2.0V
P
D
= 5.2 * 220mA) + ((5.2 - 2.0) * 40mA) + ((5.2-- 2.0) * 20mA)
PD = 1144mW + 128mW + 64mW = 1.336W
The thermal rise from junction to case is
θ
JC
* P
D
. For the metal glass package,
θ
JC
= 32 °C/W. Thus the ther-
mal rise is:
32°C/W * 1.336W = 42.7°C
The maximum case temperature is:
125°C – 42.7°C = 82.3°C
The absolute maximum power dissipation of the device is at:
V
SS
= -5.5V
I
MOD
= 60mA
I
BIAS
= 50mA
V
IBIAS
= 0V
V
IOUT
= 0V
P
D
= (5.5 * 220mA) + (5.5 * 60mA) + (5.5mA * 50mA)
P
D
= 1.815W
This will net a maximum junction to case thermal rise of: 1.815W * 32°C/W = 58°C
This situation will allow maximum case temperature of: 125°C – 58°C = 67°C
VITESSE
SEMICONDUCTOR CORPORATION
G52203-0, Rev 3.0
Page 5
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Input Termination Schemes
Figure 1: Input Structure
Figure 2: Single Ended AC Coupled
Figure 3: Differential AC Coupled
X
X
+
-
1400
1400
4300
4300
OV (GND)
-5.2V (VSS)
DIN
VREF
• Nominal VREF = -1.3V
• 1400, 4300 Ohm Resistor
on die, nominal values
X
X
SOURCE
50
Ω
50 Ohms
-2V
0.1
µ
F
0.1
µ
F
DIN
VREF
GND
VSS
+
-
GND
GND
GND
X
SOURCE
50
Ω
-2V
0.1
µ
F
DIN
X
50
Ω
-2V
0.1
µ
F
VREF
GND
VSS
+
-
GND
GND
GND
GND
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Page 6
G52203-0, Rev 3.0
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Figure 4: Differential DC Coupled
Figure 5: Single Ended AC Coupled with Offset Adjust
X
SOURCE
50
Ω
-2V
-2V
DIN
X
50
Ω
VREF
GND
VSS
+
-
GND
GND
GND
GND
X
X
SOURCE
50
Ω
.01
µ
F
DIN
VREF
GND
GND
VSS
VSS
+
-
4300
2000
.01
µ
F
GND
GND
GND
GND
VITESSE
SEMICONDUCTOR CORPORATION
G52203-0, Rev 3.0
Page 7
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Figure 6: Control Signals VIP and VIB
Figure 7: Simplified Output Structure
50 mA
60 mA
I (MIB)
I (MIP)
VIP
VIB
1.5V (Typical)
2.1V (Maximum)
1.5V (Typical)
2.1V (Maximum)
Typical Bias Current v.s. Bias Voltage
Typical Modulation Current v.s. Modulation Voltage
X
X
X
X
X
X
NIOUT
IOUT
OUTPUT
DIFF
PAIR
VIB
MIB
MIP
IP
I
MOD
I
BIAS
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Page 8
G52203-0, Rev 3.0
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Figure 8: Pad Assignments for VSC7923 Die
NOTES:
1) Die size = 1620µm x 1620µm
2) Actual die size = 1720µm x 1720µm (after die are cut up)
3) Pad size = 120µm x 120µm
4) Pad pitch = 150µm
5) Space betwen pads = 30µm
PAD 25
PAD 24
PAD 23
PAD 22
PAD 21
PAD 20
PAD 19
PAD 18
VIB
GND0
OUT
OUT
GND0
NOUT
VSS
VSS
PAD 1
PAD 34 PAD 33 PAD 32 PAD 31 PAD 30 PAD 29 PAD 28 PAD 27 PAD 26
VREF
VSS
VSS
VSS
VSS
VIP
MIP
MIP
MIB
PAD 2
PAD 3
PAD 4
PAD 5
PAD 6
PAD 7
PAD 8
DIN
VSS
DIN
GND
GND
GND
VSS
VSS
PAD 9
PAD 10 PAD 11 PAD 12 PAD 13 PAD 14 PAD 15 PAD 16 PAD 17
N/C
N/C
GND
GND
GND
GND
GND
NMARK MARK
120
µ
m
120
150
µ
m
30
µ
m
1720
µ
m
1620
µ
m
1720
µ
m
1620
µ
m
50
µ
m
50
µ
m
50
µ
m
50
µ
m
VITESSE
SEMICONDUCTOR CORPORATION
G52203-0, Rev 3.0
Page 9
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Pin Diagram for 24 Pin Metal-Glass Package
1
2
3
4
5
6
18
17
16
15
14
13
24 23 22 21 20 19
7
8
9 10 11 12
VSS
DIN
GND
GND
GND
VSS
VIB
GND
IOUT
GND
NIOUT
VSS
N/C
GND
GND
GND
MK
MK
VREF
VSS
VSS
VIP
MIP
MIB
Top
View
(LID)
Note:
Package bottom plate is connected to GND within the package.
Package lid is electrically unconnected.
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Page 10
G52203-0, Rev 3.0
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Package Information - 24 Pin Metal-Glass Package
(D) TYP
(E)
±
.002
(A) MAX
Pin 1
(LID)
Top View
(B)
(G)
(F)
(C)
MAX
Package Top
Package Lid
(I)
(H)
Side View
NOTES: Drawing not to scale.
Package #: 101-291-8 Issue #:1
Key
mm
In
A
7.11
0.280
B
6.10
0.240
C
1.02
0.040
D
0.76
0.030
E
0.30
0.012
F
2.08
0.082
G
1.02
0.040
H
9.52
0.375
I
0.13
0.005
Lid #: 101-292-3 Issue #:1
VITESSE
SEMICONDUCTOR CORPORATION
G52203-0, Rev 3.0
Page 11
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Pin Diagram for 24 Pin Ceramic Package
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
24
23
22
21
20
19
VSS
DIN
GND
GND
GND
VSS
VIB
GND
IOUT
GND
NIOUT
VSS
N/C
GND
GND
GND
NMK
MK
VREF
VSS
VSS
VIP
MIP
MIB
Note:
Package bottom plate is connected to GND within the package.
Package lid is electrically unconnected.
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Page 12
G52203-0, Rev 3.0
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Package Information - 24 Pin Ceramic Package
Top View
Side View
NOTES: Drawing not to scale.
Package #: 101-312-0 Issue #:1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
24
23
22
21
20
19
INDEX
A
E
A
D
I
C
G
F
H
J
B
Key
mm
In
A
9.5
0.374
B
7.7
0.303
C
2.0
0.079
D
1.27
0.050
E
0.30
0.012
F
1.7
0.067
G
0.6
0.024
H
11.5
0.453
I
0.125
0.005
J
8.51
0.335
L id #: 101-303-1 Issue #:1
VITESSE
SEMICONDUCTOR CORPORATION
G52203-0, Rev 3.0
Page 13
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Ordering Information
The order number for this product is formed by a combination of the device number, and package style.
Notice
Vitesse Semiconductor Corporation (“Vitesse”) provides this document for informational purposes only. This document contains pre-production
information about Vitesse products in their concept, development and/or testing phase. All information in this document, including descriptions of
features, functions, performance, technical specifications and availability, is subject to change without notice at any time. Nothing contained in this
document shall be construed as extending any warranty or promise, express or implied, that any Vitesse product will be available as described or
will be suitable for or will accomplish any particular task.
Vitesse products are not intended for use in life support appliances, devices or systems. Use of a Vitesse product in such applications without writ-
ten consent is prohibited.
VSC7923
XX
Device Type
2.5Gb/s Laser Diode Driver
Package Style (24 pin)
CA: Metal Glass Package—Straight Leads
KF: Ceramic Package—Straight Leads
KFL: Ceramic Package—Formed Leads
X:
Bare Die
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7923
SONET/SDH 2.5Gb/s Laser Diode Driver
Page 14
G52203-0, Rev 3.0
05/11/01
© VITESSE
SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com