MAX3736ETE+T Maxim Integrated Products, MAX3736ETE+T Datasheet - Page 8

• Manufacturer Part Number: MAX3736ETE+T
• Description: IC LSR DRVR 3.2GBPS 3.63V 16TQFN
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Driver (Fiber Optic)r

Specifications of MAX3736ETE+T

• Data Rate: 3.2Gbps
• Number Of Channels: 1
• Voltage - Supply: 2.97 V ~ 3.63 V
• Current - Supply: 22mA
• Current - Modulation: 85mA
• Current - Bias: 100mA
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 16-TQFN Exposed Pad
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The output stage is composed of a high-speed differ-
ential pair and a programmable modulation current
source. The MAX3736 is optimized for driving a 15Ω
load; the minimum instantaneous voltage required at
OUT+ is 0.6V. Modulation current swings up to 60mA
are possible.
To interface with the laser diode, a damping resistor (R
is required for impedance matching. The combined
resistance of the series damping resistor and the equiva-
lent series resistance of the laser diode should equal
15Ω. To reduce optical output aberrations and duty-
cycle distortion caused by laser diode parasitic induc-
tance, an RC shunt network might be necessary. Refer to
Application Note 274: HFAN-02.0: Interfacing Maxim
Laser Drivers with Laser Diodes for more information.
At high data rates, e.g., 2.5Gbps, any capacitive load at
the cathode of a laser diode degrades optical output per-
formance. Because the BIAS output is directly connected
to the laser cathode, minimize the parasitic capacitance
associated with the pin by using an inductor to isolate the
BIAS pin parasitics from the laser cathode.
In the absence of input data, the modulation current
switches to OUT-, squelching the transceiver output.
The DIS pin disables the modulation and bias current.
The typical enable time is 2µs for bias current and 1µs
for modulation current. The typical disable time is 200ns
for bias current and 250µs for modulation current. The
DIS pin has a 7.4kΩ internal pullup resistor.
There are three methods for setting the modulation cur-
rent on the MAX3736 laser driver. The current can be
set by using a current DAC, a voltage DAC in series with
a resistor, or by using a resistor connected to GND.
To program the laser modulation current using a cur-
rent DAC, attach the DAC to the MODSET pin and set
the current using the following equation:
3.2Gbps, Low-Power, Compact,
SFP Laser Driver
8
_______________________________________________________________________________________
Programming the Modulation Current
High-Speed Modulation Driver
I
MOD
=
I
MODSET
Design Procedure
× 85
Disable
D
)
To program the laser modulation current using a volt-
age DAC, attach the DAC to the MODSET pin through a
series resistor, R
following equation:
To program the laser modulation current using a resis-
tor, place the resistor from MODSET to ground. I
current can be calculated by the following equation:
There are three methods for setting the bias current on
the MAX3736 laser driver. The current can be set by
using a current DAC, a voltage DAC in series with a
resistor, or by using a resistor connected to GND.
To program the laser bias current using a current DAC,
attach the DAC to the BIASSET pin and set the current
using the following equation:
To program the laser bias current using a voltage DAC,
attach the DAC to the BIASSET pin through a series
resistor, R
ing equation:
To program the laser bias current using a resistor,
place the resistor from BIASSET to ground. I
rent can be calculated by the following equation:
SERIES
I
I
MOD
BIAS
I
Programming the Bias Current
, and set the current using the follow-
MOD
SERIES
I
BIAS
I
BIAS
=
=
=
1 2
=
1 2
=
, and set the current using the
.
R
.
R
R
R
I
MODSET
BIASET
V V
V V
SERIES
SERIES
BIASET
1 2
1 2
−
.
−
.
V
V
DAC
DAC
× 85
×
×
×
85
×
85
85
85
BIAS
MOD
cur-