MAX3656ETG+T Maxim Integrated Products, MAX3656ETG+T Datasheet - Page 12

• Manufacturer Part Number: MAX3656ETG+T
• Description: IC LASR DRVR 2.5GBPS 3.6V 24TQFN
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Driver (Fiber Optic)r

Specifications of MAX3656ETG+T

• Data Rate: 2.5Gbps
• Number Of Channels: 1
• Voltage - Supply: 3 V ~ 3.6 V
• Current - Supply: 40mA
• Current - Modulation: 85mA
• Current - Bias: 70mA
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 24-TQFN Exposed Pad
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MAX3656ETG+T; MAX3656ETG+TTR

155Mbps to 2.5Gbps Burst-Mode
Laser Driver
Select a communication-grade laser for the proper data
rate. Assume the laser output average power is P
0dBm, the operating temperature is -40°C to +85°C
and the laser diode has the following characteristics:
wavelength: λ = 1.3µm, threshold current: I
at +25°C, threshold temperature coefficient: β
1.3%/°C, laser-to-monitor transfer: ρ
(ρ
and laser slope efficiency: η = 0.05mW/mA at +25°C.
The desired monitor diode current is estimated by I
P
Typical Operating Characteristics shows R
Figure 4. Connecting to PECL Outputs
12
AVG
MON
______________________________________________________________________________________
✕
= ρ
ρ
MON
Z
Z
Z
Z
O
O
O
O
MONITORDIODE
= 50Ω
= 50Ω
= 50Ω
= 50Ω
= 200µA. The I
V
V
CC
CC
130Ω
82Ω
130Ω
82Ω
x L
Determining R
MD
V
V
CC
CC
Design Example
LASER-TO-MONITORDIODE)
130Ω
82Ω
130Ω
82Ω
vs. R
IN+
IN-
BEN+
BEN-
APCSET
Select Laser
MON
APCSET
MAX3656
TH
graph in the
= 0.2A/W
APCSET
= 22mA
at 12kΩ.
AVG
MD
TH
=
=
=
,
,
Assuming r
the peak-to-peak optical power P
The required modulation current is 1.64(mW)/0.05(mW/mA)
= 32.8mA. The I
Operating Characteristics shows R
Determine the maximum threshold current (I
T
50mA, the maximum bias current should be:
In this example, I
vs. R
eristics shows R
Figure 6. Single-Ended Biasing for Burst Enable
Figure 5. Connecting to CML Outputs
A
= +85°C and end of life. Assuming (I
V
V
V
CMBEN
CMBEN
CMBEN
BIASMAX
+ (100mV to 800mV)
- (100mV to 800mV)
Z
Z
Z
Z
e
O
O
O
O
= 50Ω
= 50Ω
= 50Ω
= 50Ω
= 10 and an average power of 0dBm (1mW),
graph in the Typical Operating Charact-
V
BIASMAX
MOD
CMBEN
I
BIASMAX
100Ω
100Ω
BIASMAX
= +2.0V
vs. R
3.3V
at 8kΩ.
Determining R
MODSET
Determining R
= I
R
R
1
2
IN+
IN-
BEN+
BEN-
= 1.65kΩ
= 2.54kΩ
TH(MAX)
= 50mA. The I
P-P
MODSET
MAX3656
graph in the Typical
= 1.64mW (Table 1).
at 9kΩ.
IN+
IN-
BEN+
BEN-
MAX3656
TH(MAX)
TH(MAX)
BIASMAX
MODSET
BIASMAX
) at
) =