19-1097; Rev 3; 7/04
Low-Power, 622Mbps Limiting Amplifiers
with Chatter-Free Power Detect for LANs
_______________General Description
____________________________Features
The MAX3761/MAX3762 limiting amplifiers, with 4mV
sensitivity and PECL data outputs, are optimized for
operation in low-cost, 622Mbps, LAN/ATM LAN fiber
optics applications.
ꢀ Chatter-Free Power Detector with Programmable
Loss-of-Signal Outputs
ꢀ 4mV Input Sensitivity (PECL Loss-of-Signal
Interface Logic—MAX3766
An integrated power detector senses the input signal’s
amplitude. A received-signal-strength indicator (RSSI)
gives an analog indication of the power level, while the
complementary loss-of-signal (LOS) outputs indicate if
the input power level exceeds the programmed
threshold level. The LOS threshold can be adjusted to
detect signal amplitudes between 3mVp-p and
100mVp-p, providing a 15dB LOS adjustment in fiber
optic receivers. The LOS outputs have 3.5dB of
hysteresis, which prevents chatter when input signal
levels are small. The MAX3761’s LOS outputs are com-
patible with TTL-logic levels. The MAX3762 has PECL
LOS outputs.
ꢀ PECL Data Outputs
ꢀ Single 5V Power Supply
ꢀ 250ps Output Edge Speed
ꢀ Low 15ps Pulse-Width Distortion
ꢀ TTL Loss-of-Signal Interface Logic—MAX3761
Ordering Information
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 QSOP
Dice*
MAX3761EEP
MAX3761C/D
MAX3762EEP
MAX3762EEP+
MAX3762C/D
DISABLE and LOS can be used to implement a squelch
function, which turns off the data outputs when the
input signal is below the programmed threshold.
20 QSOP
20 QSOP
Dice*
________________________Applications
622Mbps LAN/ATM LAN Receivers
*Dice are designed to operate from -40°C to +85°C, but are
tested and guaranteed only at T = +25°C.
A
+Denotes lead free package.
155Mbps LAN/ATM LAN Receivers
__________________Pin Configuration
_________Typical Operating Circuits
C
TOP VIEW
AZ
+5V
CZP
V
CC
150pF
CZN
EN
FILTER
RSSI
EN
DISABLE
LOS+
1
2
20
19
18
17
16
15
14
13
12
11
10nF
DISABLE
LOS+
RSSI
VCCO
LOS-
3
LOS-
C
100pF
BYPASS
SUPPLY
IN
V
CC
5.6nF
V
OUT-
4
CC
VIN+
MAX3761
MAX3762
VIN+
VIN-
GND
SUB
OUT+
VCCO
OUT+
OUT-
GNDO
VTH
5
50Ω
C
IN
6
5.6nF
MAX3761
50Ω
VIN-
FILTER
INV
GNDO
GND
SUB
7
V
- 2V
CC
8
C
100pF
+V
FILTER
CZP
CZN
VTH
9
CC
INV
10
R1
R2
100kΩ
22kΩ
QSOP
MAX3762 at end of data sheet.
________________________________________________________________ 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.