ADN2848ACPZ-32-RL7 Analog Devices Inc, ADN2848ACPZ-32-RL7 Datasheet - Page 9

IC,Laser Diode/LED Driver,LLCC,32PIN,PLASTIC

ADN2848ACPZ-32-RL7

Manufacturer Part Number
ADN2848ACPZ-32-RL7
Description
IC,Laser Diode/LED Driver,LLCC,32PIN,PLASTIC
Manufacturer
Analog Devices Inc
Type
Laser Diode Driver (Fiber Optic)r
Datasheet

Specifications of ADN2848ACPZ-32-RL7

Data Rate
1.25Gbps
Number Of Channels
1
Voltage - Supply
3 V ~ 3.6 V
Current - Supply
50mA
Current - Modulation
80mA
Current - Bias
100mA
Operating Temperature
-40°C ~ 85°C
Package / Case
32-VFQFN, CSP Exposed Pad
Mounting Type
Surface Mount
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
POWER CONSUMPTION
The ADN2848 die temperature must be kept below 125°C. The
LFCSP_VQ package has an exposed paddle. The exposed
paddle should be connected in such a manner that it is at the
same potential as the ADN2848 ground pins. The θ
package is shown under the Absolute Maximum Ratings. Power
consumption can be calculated using
I
P = V
T
Thus, the maximum combination of I
calculated
where:
I
I
T
T
V
V
V
LASER DIODE INTERFACING
Many laser diodes designed for 1.25 Gbps operation are
packaged with an internal resistor to bring the effective
impedance up to 25 Ω in order to minimize transmission line
effects. In high current applications, the voltage drop across this
resistor, combined with the laser diode forward voltage, makes
direct connection between the laser and the driver impractical
in a 3 V system. AC coupling the driver to the laser diode
removes this headroom constraint.
CC
CCMIN
BIAS
DIE
DIE
AMBIENT
BIAS_PIN
MODP_PIN
MODN_PIN
= I
= I
= T
= die temperature.
CC
= 50 mA, the typical value of I
CCMIN
MOD
= voltage at I
AMBIENT
× I
= ambient temperature.
= average voltage at IMODP pin.
= average voltage at IMODN pin.
= 0.
CC
+ 0.3 I
+ (I
+ θ
BIAS
MOD
JA
× P
BIAS
× V
pin.
BIAS_PIN
) + I
MOD
CC
BIAS
provided on Page 3 with
(V
+ I
MODP_PIN
MOD
must be
+ V
JA
for the
MODN_PIN
Rev. A | Page 9 of 12
)/2
Caution must be used when choosing component values for
ac coupling to ensure that the time constants (L/R and RC, see
Figure 9) are sufficiently long for the data rate and the expected
number of CIDs (consecutive identical digits). Failure to do this
could lead to pattern dependent jitter and vertical eye closure.
For designs with low series resistance, or where external
components become impractical, the ADN2848 supports direct
connection to the laser diode (see Figure 8). In this case, care
must be taken to ensure that the voltage drop across the laser
diode does not violate the minimum compliance voltage on the
IMODP pin.
OPTICAL SUPERVISOR
The PSET and ERSET potentiometers can be replaced with a
dual digital potentiometer, the ADN2850 (see Figure 7). The
ADN2850 provides an accurate digital control for the average
optical power and extinction ratio and ensures excellent
stability over temperature.
Figure 7. Application Using the ADN2850 Dual 10-Bit Digital Potentiometer
with Extremely Low Temperature Coefficient as an Optical Supervisor
CLK
CS
Rx
Tx
SDI
SDO
CLK
CS
ADN2850
V
CC
IDTONE
DATAP
DATAN
DAC1
DAC2
PSET
ERSET
IMPD
V
ADN2848
CC
IMODP
I
BIAS
ADN2848
V
CC

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