MAX3850EGJ Maxim Integrated Products, MAX3850EGJ Datasheet - Page 11

• Manufacturer Part Number: MAX3850EGJ
• Description: Laser Driver
• Manufacturer: Maxim Integrated Products

Assuming r
then according to Table 1, the peak-to-peak optical
power P
is 1.81(mW) / 0.05(mW/mA) = 36.2mA. The I
R
shows R
Determine the maximum threshold current (I
T
50mA, the maximum bias current should be:
In this example, I
R
Characteristics shows R
Table 2. Bondpad Locations
*Index pad. Orient the die with this pad in the lower-left corner.
A
MODSET
BIASMAX
= +85°C and end of life. Assuming (I
PAD
*12
10
11
13
14
15
16
17
18
19
20
21
22
23
24
1
2
3
4
5
6
7
8
9
P-P
MODSET
graph in the Typical Operating Characteristics
e
= 1.81mW. The required modulation current
= 20, and average power of 0dBm (1mW),
graph
at 5.5kΩ.
MODMON
BIASMON
I
ENABLE
APCFILT
DATA+
BIASMAX
BIASMAX
LATCH
______________________________________________________________________________________
NAME
DATA-
2.7Gbps, +3.3V DC-Coupled Laser Driver
GND2
GND1
GND1
GND1
GND1
GND1
GND4
GND4
CLK+
V
V
V
CLK-
V
V
FAIL
N.C.
CC1
CC1
CC1
CC1
CC4
in
BIASMAX
the
= I
= 50mA. The I
Determine R
Determine R
TH(MAX)
at 5kΩ.
Typical
1091
1213
1334
1456
1577
205
351
484
605
727
848
970
46
46
46
46
46
46
46
46
46
46
46
46
X
COORDINATES
BIASMAX
BIASMAX
TH(MAX)
Operating
TH(MAX)
MODSET
MOD
1523
1334
1213
1091
970
848
727
605
484
362
241
46
46
46
46
46
46
46
46
46
46
46
46
46
Y
) at
) =
vs.
vs.
For applications requiring modulation current greater
than 60mA, headroom is insufficient for proper opera-
tion of the laser driver if the laser is DC-coupled.
To avoid this problem, the MAX3850’s modulation out-
put 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 supply voltage (V
Note HFAN 2.0 Interfacing Maxim’s Laser Drivers to
Laser Diodes for more information on AC-coupling laser
drivers to laser diodes.
PAD
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Modulation Currents Exceeding 60mA
BIASMAX
MODSET
APCSET
NAME
OUT+
GND4
GND3
GND3
CAPC
GND3
GND3
GND2
OUT-
V
V
V
V
BIAS
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
MD
CC4
CC4
CC3
CC2
CC)
CC
. Such a configuration isolates
. Refer to Maxim Application
1709
1861
1861
1861
1861
1861
1861
1861
1861
1861
1861
1709
1577
1456
1334
1213
1091
970
848
727
605
484
351
205
X
COORDINATES
1102
1223
1356
1523
1523
1523
1523
1523
1523
1523
1523
1523
1523
1523
1523
1523
241
373
494
616
737
859
980
46
Y
11