19-3181; Rev 0; 2/04
3.2Gbps SFP Transimpedance
Amplifiers with RSSI
General Description
Features
The MAX3724/MAX3725 transimpedance amplifiers pro-
vide a compact, low-power solution for communication
up to 3.2Gbps. They feature 325nA input-referred noise
at 2.1GHz bandwidth (BW) with 0.6pF input capaci-
♦ Wider Bandwidth than MAX3744/MAX3745
♦ RSSI Implementation in 4-Pin TO-46 Header
(MAX3724 and MAX3748A)
tance. The parts also have >2mA
AC input overload.
P-P
♦ 8ps
Deterministic Jitter for <100µA
Input
P-P
P-P
Both parts operate from a single +3.3V supply and con-
sume 93mW. The MAX3724/MAX3725 are in a compact
30-mil x 50-mil die and require no external compensa-
tion capacitor. A space-saving filter connection is pro-
vided for positive bias to the photodiode through an
Current
♦ 325nA
Input-Referred Noise at 2.1GHz
RMS
Bandwidth
♦ 28mA Supply Current at +3.3V
♦ 2.5GHz Small-Signal Bandwidth
on-chip 580Ω resistor to V . These features allow
CC
easy assembly into a low-cost TO-46 or TO-56 header
with a photodiode.
♦ 2.0mA
AC Overload
P-P
The MAX3724 and MAX3748A receiver chip set pro-
vides an RSSI output using a Maxim-proprietary* inter-
face technique. The MAX3724 preamplifier, MAX3748A
postamplifier, and the DS1858/DS1859 SFP controller
meet all the SFF-8472 digital diagnostic requirements.
♦ Die Size: 30 mils x 50 mils (Identical to the
MAX3744/MAX3745)
Applications
Ordering Information
Up to 3.2Gbps SFF/SFP Optical Receivers
PART
MAX3724E/D
MAX3725E/D
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
Dice**
Optimized for Small-Form-Factor Pluggable (SFP)
Optical Receivers
Dice**
**Dice are designed to operate with junction temperatures of
*Patent pending.
-40°C to +110°C but are tested and guaranteed only at T
+25°C.
=
A
Typical Application Circuit
SFP OPTICAL RECEIVER
V
CC
400pF
V
CC
400pF
0.1
0.1
µ
µ
F
F
HOST
BOARD
V
CC
OUT+
OUT-
IN+
IN-
OUT+
FILTER
MAX3724
OUT-
MAX3748A
V
= 3.3V
CC
IN
GND
4.7kΩ
TO
RSSI
DISABLE
LOS
4-PIN TO CAN
10kΩ
3.3k
Ω
MOD-DEF1
MOD-DEF2
DS1858/
DS1859
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.