MAX3738ETG+ Maxim Integrated Products, MAX3738ETG+ Datasheet - Page 13

• Manufacturer Part Number: MAX3738ETG+
• Description: IC LASER DRIVER 4.25GBPS 24TQFN
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Driver (Fiber Optic)r

Specifications of MAX3738ETG+

• Data Rate: 4.25Gbps
• Number Of Channels: 1
• Voltage - Supply: 2.97 V ~ 3.63 V
• Current - Supply: 47mA
• Current - Modulation: 85mA
• Current - Bias: 100mA
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 24-TQFN Exposed Pad
• Mounting Type: Surface Mount
• Operating Supply Voltage: 3.3 V
• Supply Current: 47 mA
• Maximum Operating Temperature: + 85 C
• Maximum Power Dissipation: 1805 mW
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The minimum voltage at the OUT+ and OUT- pins
is 0.7V.
For:
V
R
R
For compliance:
For applications requiring modulation current greater
than 60mA, headroom is insufficient from proper opera-
tion of the laser driver if the laser is DC-coupled. To
avoid this problem, the MAX3738’s modulation output
can be AC-coupled to the cathode of a laser diode. An
external pullup inductor is necessary to DC-bias the
modulation output at V
laser forward voltage from the output circuitry and allows
the output at OUT+ to swing above and below the sup-
ply voltage (V
modulation current can be programmed up to 85mA.
Refer to Application Note 274: HFAN-02.0: Interfacing
Figure 6. Simplified Input Structure
IN+
DIODE
L
D
IN-
0.11pF
0.11pF
= Diode bias point resistance (5Ω typ)
= Series matching resistor (20Ω typ)
V
OUT+
= Diode bias point voltage (1.2V typ)
PACKAGE
Current Compliance (I
Current Compliance (I
155Mbps to 4.25Gbps SFF/SFP Laser Driver
= V
0.7nH
0.7nH
I
CC
BIAS
CC
). When AC-coupled, the MAX3738
______________________________________________________________________________________
- V
x R
MAX3738
DIODE
CC
V
V
L
CC
CC
≥ 0.7V
. Such a configuration isolates
5kΩ
5kΩ
- I
16kΩ
24kΩ
MOD
x (R
V
CC
MOD
MOD
D
DC-Coupled
AC-Coupled
+ R
> 60mA),
≤ ≤ 60mA),
L
with Extinction Ratio Control
) -
Maxim Laser Drivers with Laser Diodes for more informa-
tion on AC-coupling laser drivers to laser diodes.
For compliance:
The APC loop filter capacitor (C
to balance the requirements for fast turn-on and mini-
mal interaction with low frequencies in the data pattern.
The low-frequency cutoff is:
High-frequency noise can be filtered with an additional
cap, C
The MAX3738 is designed so turn-on time is faster than
1ms for most laser gain values (η x ρ
smaller value of C
balance between turn-on time and low-frequency cutoff
may be needed at low data rates for some values of
laser gain.
Figures 6 and 7 show simplified input and output cir-
cuits for the MAX3738 laser driver. If dice are used,
replace package parasitic elements with bondwire par-
asitic elements.
Figure 7. Simplified Output Structure
V
C
MD
OUT+
APC
, from the MD pin to ground.
(µF) ≅ 68 / (f
= V
CC
APC
- I
C
MD
MOD
3dB
reduces turn-on time. Careful
≅ C
V
CC
/ 2 x (R
(kHz) x (η x ρ
APC
APC
/ 4
Interface Models
D
Determine C
+ R
) must be selected
MON
MAX3738
0.7nH
0.7nH
PACKAGE
L
) ≥ 0.75V
MON
). Choosing a
)
1.1
0.11pF
0.11pF
)
OUT-
OUT+
APC
13