Sony CXB1549Q Datasheet

CXB1549Q

Laser Diode Driver

Description

The CXB1549Q is a high-speed monolithic Laser
Diode Driver/Current Switch with ECL/PECL input
level. Open collector outputs are provided at the
output pins (Q, QBX) and have the capacity of driving
modulation current of 50mAp-p at a max. data rate of

1.25Gbps (Min.). Along with the modulation current
generator there is the laser diode bias generator
which has capacity of sourcing up to 60mA (Bias).
The laser diode current can be controlled by either a
voltage or current into the bias adjust pin (BiasAdj) and
the bias set pin (SBias), depending on how these
pins are configured. Control of the diode bias current
is achieved through the APC (Automatic Power
Control) circuitry. In order to avoid having a large
current go through the laser diode, this IC also
provides an Activity detector and Power on Reset
functions for Laser Safety. The Activity detector
circuit detects data edge transitions and if no data
transition occur after a certain time period, then both
the modulation and bias current are shutdown.

The Power on Reset circuit holds the modulation
and bias current off for a set period of time while the
system power is applied. Additionally, this IC has an
internal Duty Cycle correction circuit that can control
the falling edge of the input pulse up to a maximum
of 0.2ns (Min.).

Features

• Maximum data rate (NRZ): 1.25Gbps

• Power on Reset function

• Alarm and Shutdown function

• Signal Duty cycle correction

• Automatic Power Control (APC) for bias current

• Activity detector function for laser safety

• Power indicate function

• Differential PECL inputs or AC coupled inputs

Application

• Gbit-ethernet: 1.25Gb/s

• SONET/SDH: 622Mb/s

• Fibre channel: 532Mb/s, 1.062Gb/s

Absolute Maximum Ratings

• Supply voltage Vcc – VEE –0.3 to +6.0 V

• Input voltage VIN VEE to Vcc V

• Differential input voltage

| VD – VDB | 0 to 2.5 V

• Bias output current 0 to 80 mA

• Modulation output current 0 to 70 mA

• SBias input/output current 0 to 5 mA

• Input bias control current

Iset (Ibiasadj) 0 to 5 mA

• Input bias control voltage
Vset (Vbiasadj) 0 to 3 V

• Storage temperature
Tstg –65 to +150 °C

Recommended Operating Conditions

• DC power supply voltage

Vcc – VEE 3.14 to 3.46 V

• Operating ambient temperature
Ta –40 to +85 °C

Structure

Bipolar silicon monolithic IC

– 1 –

E98313B92-PS

Sony reserves the right to change products and specifications without prior notice. This information does not convey any license by
any implication or otherwise under any patents or other right. Application circuits shown, if any, are typical examples illustrating the
operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits.

40 pin QFP (Plastic)

– 2 –

CXB1549Q

Block Diagram and Pin Assignment

VBB
Generator

VREF

Power on
Reset

Reference
Generator

Bias
Circuit

DRV Cont

In_ALM

35

36

37

34

29 24

RS

28

RSB

27

Tset

26

Indicate

25

VBB

VCC2

D

DB

V

EE2

Q

V

EE5

Bias

SBias

V

CC4

23 22 21

20 ADCDis

16 CompB

15

CompA

19 TM

18 NC

17 Timer

14

DrvAdj

38

V

EE3

CapZ

V

CC3

V

REF

TEST_PIN

SDNB

SDN

LDAlm

39

APCOut

40RsetPD

31

32

33

30

LDAlmB

7

QBX

8

VEE19VEE1

10

DrvMon

11

V

EE1

12

V

CC1

13

6541

VEE4

2

BiasAdj

3

Duty Cycle
Cont

– 3 –

CXB1549Q

Pin Description

Pad

No.

1 VCC4 3.3

Positive power supply
pin for APC circuit.

2 VEE4 0

Negative power supply
pin for APC circuit.

6 VEE5 0

Negative power supply
pin for Bias circuit.

7 Q 1.3 to 3.3

6mA to
30mA

∗1

6mA to
50mA

∗2

8

QBX

1.3 to 3.3

6mA to
30mA

∗1

6mA to
50mA

∗2

Laser modulation
current output pin.
Open collector output.

9, 10 VEE1 0

Negative power supply
pin for Driver circuit.

11 VCC1 3.3

Positive power supply
pin for Driver circuit.

12 VEE1 0

Negative power supply
pin for Driver circuit.

13

DrvMon

0µA

to

600µA

Sets Laser modulation
current (IQ) monitor pin.
IQ is monitored by
connecting a resistor
(Rmon) to this pin.

14

DrvAdj

0µA

to

600µA

Sets Laser modulation
current pin (IQ).
IQ is controlled by
connecting a resistor
(Rdrv) to this pin.
Refer to Fig.2.

3 BiasAdj

1.5 to 0

Sets Laser bias current
pin.

4 SBias

0mA

to

2.5mA

Sets Laser bias current
or monitor pin.

5 Bias

0mA

to

60mA

Laser bias current
output pin.
Open collector output.

Symbol

Typical voltage [V]

DC AC

Equivalent circuit Description

3

VCC

VEE

10pF

240

30

8

4 5

VEE

7 8

Current
Source

VCC

VEE

1.3k

150

150

Rdrv

Rmon

13

14

∗1

Ta = –40 to 0°C

∗2

Ta = 0 to +85°C

Complementary current
output pin.
Q and QBX are
not symmetrical output.
Use Q output for Laser
modulation.

– 4 –

CXB1549Q

Pad

No.

15 CompA

Modulation current
driver compensation pin.
Normally, connects
180pF Capacitor across
CompA and CompB
pins.

16 CompB

Capacitor port pin for
activity detector
(IN_ALM) operation.
This pin set the period
of inactive time for
activity detector.
Inactive time is
controlled by connecting
a capacitor to this pin.
Refer to Fig.6.

17 Timer

No Connect pin.18 NC

Chip temperature
monitor pin.

19 TM 1.5

This pin control the
activity detector Circuit.
High (connected to Vcc
or open): an activity
detector is disable.
Low (connected to VEE):
an activity detector is
enable.

20 ADCDis

VEE

to

VCC

(open)

Negative power supply
pin for Data input circuit.

21

VEE2 0

Symbol

Typical voltage [V]

DC

AC

Equivalent circuit Description

VCC

VEE

30pF

180pF

10k

15
16

VCC

2.1k

VEE

17

10pF

200µA

Ctimer

25µA

2.4k

2.4k

VEE

19 21

VCC

VEE

3.8k3.8k

15µA

35k
35k
35k
35k

20

– 5 –

CXB1549Q

Pad

No.

22

DB 1.6 to 2.4

23

D 1.6 to 2.4

24 VCC2 3.3

25 VBB 2

26 Indicate 0.7 to 1.7

Differential PECL data
inputs pins.
These two inputs are
internally biased by
10kΩ to VBB.

Positive power supply
pin for Data input circuit.

Reference bias voltage.
(Option)

The analog voltage high
impedance output pin
which indicate of whether
the optical power of
Laser diode is operated
normal
or not. The power output
range has following
relationship.
High Light Indication;

Vo ≥ 1.7V

Nominal Operation;

Vo = 1.2V

Low Light Indication;

Vo ≤ 0.7V

Symbol

Typical voltage [V]

DC AC

Equivalent circuit Description

24

22 25

21

300

200

200

10k

10k

300

600µA

23

600µA

400

26

100k

V

CC

VEE

14k

50µA

35µA 35µA

27 Tset

Selector for output duty
cycle control pin.
This pin controls the
trailing edge of the input
high pulse. Variable
delay limit of that is from
0 to 0.2ns. Duty cycle is
controlled by connected
a resistor value between
Vcc and this pin.
Refer to Fig.1.

VCC

VEE

Rset

27

2.4k2.4k
20pF

70µA

140220

28 RSB 0.5

29 RS 2.5

Window comparator
top/bottom threshold
voltage pin for
LD_ALARM.
The alarm (fail)
threshold assert voltage
can be set by the
external resistor.
Default voltages are
RS equal to 2.5V and
RSB equal to 0.5V.

29

28

VCC

VEE

100µA

2.5k

20k

5k

– 6 –

CXB1549Q

Pad

No.

30

LDAlmB 0.2 to 3

31

LDAlm 0.2 to 3

32

SDN 0 to 3.3

33

SDNB 0 to 3.3

34

VREF 1.7

Complementary open
collector TTL outputs.
Asserted when the fault
is detected in the Laser
monitor diode circuit.

Complementary TTL
inputs pin to disable
output current.
(shutdown input)
When left open = "High"

Temperature
compensated reference
voltage pin for APC.

1.7V (Constant for VEE
reference)

Symbol

Typical voltage [V]

DC AC

Equivalent circuit Description

VCC

VEE

4.7k

4.7k

31

30

VCC

VEE

5k

5k

5k

5k

300

300

60µA

60µA

32
33

300300

1.9mA

VCC

VEE

200

34

2.4k

9.1k

35

TEST_
PIN

OPEN

Do not connect.

36

VCC3 3.3

Positive power supply
pin for Signal Detect
circuit.