MAX3905 MAXIM [Maxim Integrated Products], MAX3905 Datasheet - Page 9

• Manufacturer Part Number: MAX3905
• Description: 150Mbps Automotive VCSEL Driver
• Manufacturer: MAXIM [Maxim Integrated Products]

programmed by the LOW1 and LOW2 inputs. Connect
LOW1 or LOW2 to ground to set the bit high, and leave
open to set the bit low. Do not connect LOW1 or LOW2
to V
The typical low current at T
where, LOW[1, 2] = 1 when bonded to ground; LOW[1, 2]
= 0 when left open.
The temperature coefficient of the bias current is pro-
grammed by the TC1, TC2, and TC3 inputs. Connect
TC1, TC2, or TC3 to ground to set the bit high, and
leave open to set the bit low. Do not connect TC1, TC2,
or TC3 to V
The typical temperature coefficient of the bias current
can be calculated by:
where, TC[1, 2, 3] = 1 when bonded to ground; TC[1, 2,
3] = 0 when left open.
A temperature sensor is incorporated into the MAX3905
to aid in evaluation of thermal performance. The
TEMPSENS voltage is proportional to the die junction
temperature (approximately -1.39mV per °C). The tem-
perature of the die can be estimated as:
The OUT pad connects directly to the VCSEL cathode.
The OUT pad must be connected to the VCSEL anode
or to V
OUT pad is 0.9V.
I
LOW
CC
T C
.
CC
( )
TC
°
≈ [1.8 + (0.37 x LOW1) + (0.73 x LOW2)]mA
. The minimum instantaneous voltage on the
LOW
CC
≈
.
597
≈ [16 + (5 x TC1) + (11 x TC2) +
Junction-Temperature Sensing
°
_______________________________________________________________________________________
C V
(16 x TC3)]µA/°C
-
TEMPSENS
J
= DT
150Mbps Automotive VCSEL Driver
0
(
can be calculated by:
mV x
)
Output Driver
0 72
.
1
mV
°
C
For more information and design assistance, refer to
Maxim Design Note HFDN-32.0: Output Current
Calculator for the MAX3905.
Load inductance on OUT and OUT should be matched
within 1.5nH to minimize both jitter and supply noise
generation.
For high-current density and reliable operation, the
MAX3905 uses gold metalization. For best results, use
gold-wire ball-bonding techniques. Exercise caution
when wedge bonding. Die size is 1.52mm x 1.52mm
(60 mils x 60 mils), and die thickness is 300µm
(12 mils). The bond-pad passivation opening is 93µm x
93µm and bond-pad metal thickness is 1.2µm. Refer to
Maxim Application Note HFAN-08.0.1: Understanding
Bonding Coordinates and Physical Die Size for addi-
tional information on bondpad coordinates. Do not
attempt to bond to the laser trim target.
Using the MAX3905 VCSEL driver alone does not
ensure that a transmitter design is compliant with
IEC 825. The entire transmitter circuit and component
selections must be considered. Determine the level of
fault tolerance required by each application, and rec-
ognize that Maxim products are not designed or autho-
rized for use as components in systems intended for
surgical implant into the body, for applications intended
to support or sustain life, or for any other application
where the failure of a Maxim product could create a sit-
uation where personal injury or death may occur.
Applications Information
Additional Design Assistance
Laser Safety and IEC 825
Layout Considerations
Wire Bonding
9