MAX3262CAG ,1Gbps, high-speed limiting amplifier with catter-free loss-of-signal detection.Applications AMAX3262C/D 0°C to +100°C (T ) Dice*J1062Mbps Fibre Channel*Dice are designed to opera ..
MAX3263CAG ,Single +5V / Fully Integrated / 155Mbps Laser Diode DriverMAX326319-0432; Rev 1b; 4/98Single +5V, Fully Integrated,155Mbps Laser Diode Driver________________
MAX3263CAG+ ,Single +5V / Fully Integrated / 155Mbps Laser Diode DriverFeaturesThe MAX3263 is a complete, easy-to-program, single♦ Rise Times Less than 1ns+5V-powered, 15 ..
MAX3264CUE ,3.0V to 5.5V / 1.25Gbps/2.5Gbps Limiting AmplifiersFeaturesThe 1.25Gbps MAX3264/MAX3268 and the 2.5Gbps +3.0V to +5.5V Supply VoltageMAX3265/MAX3269 ..
MAX3265 ,+3.0V to +5.5V, 1.25Gbps/2.5Gbps Limiting AmplifiersFeaturesThe 1.25Gbps MAX3264/MAX3268/MAX3768 and the ♦ +3.0V to +5.5V Supply Voltage2.5Gbps MAX3265 ..
MAX3265CUB ,3.0V to 5.5V / 1.25Gbps/2.5Gbps Limiting AmplifiersMAX3264/MAX3265/MAX3268/MAX326919-1523; Rev 1; 1/003.0V to 5.5V, 1.25Gbps/2.5Gbps Limiting Amplifie ..
MAX691CWE ,Microprocessor Supervisory Circuits19-02 18; He V 2; 4/95
MAX691CWE ,Microprocessor Supervisory CircuitsELECTRICAL CHARACTERISTICS
(Vcc = full operating range, VBATT = 2.8V, T, = 25°C, unless otherwis ..
MAX691CWE ,Microprocessor Supervisory Circuits19-02 18; He V 2; 4/95
MAX691CWE ,Microprocessor Supervisory CircuitsELECTRICAL CHARACTERISTICS
(Vcc = full operating range, VBATT = 2.8V, T, = 25°C, unless otherwis ..
MAX691CWE ,Microprocessor Supervisory CircuitsFeatures
. Precision Voltage Monitor
4.65V in MAX690, MAX691, MAX694 and MAX695
4.40V in MAX69 ..
MAX691CWE+ ,Microprocessor Supervisory CircuitsElectrical CharacteristicsV = full operating range, V = 2.8V, T = +25°C, unless otherwise noted.)CC ..
MAX3262CAG
1Gbps, high-speed limiting amplifier with catter-free loss-of-signal detection.
________________General DescriptionThe MAX3262 limiting amplifier with its high gain and
wide bandwidth is ideal for use as a post amplifier in
fiber-optic receivers with data rates up to 1Gbps. The
amplifier’s gain can be adjusted between 33dB and
48dB. At maximum gain, signals as small as 6mVp-p
can be amplified to drive devices with PECL inputs.
The MAX3262 has complementary loss-of-signal out-
puts for interfacing with open-fiber-control (OFC) cir-
cuitry. These outputs can be programmed to assert
with input levels between 9mVp-p and 48mVp-p. LOS
hysteresis for any programmed level is nominally
3.0dB, preserving a balance between noise immunity
and dynamic range.
________________________Applications1062Mbps Fibre Channel
622Mbps SONET
____________________________Features900MHz Bandwidth48dB Maximum Gain Chatter-Free LOSProgrammable LOS ThresholdSingle +5V Power SupplyFully Differential Architecture
_______________Ordering Information
MAX3262
1Gbps, High-Speed Limiting Amplifier with
Chatter-Free Loss-of-Signal Detection
____________________________________________________Typical Operating Circuit19-0324; Rev 2; 12/97
Pin Configuration appears at end of data sheet.*Dice are designed to operate over this range but are tested and
guaranteed only at TA= +25°C.
MAX3262
1Gbps, High-Speed Limiting Amplifier with
Chatter-Free Loss-of-Signal Detection
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS(VCC= +5V, RLOAD= 50Ωto VCC- 2V (equivalent), TA= 0°C to +70°C. Typical values are at VCC= 5V and TA= +25°C.)
AC ELECTRICAL CHARACTERISTICS(VCC= +5V, RLOAD= 50Ωto 3V, AC parameters are not tested, TA= +25°C, unless otherwise noted.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Note 1:Input is a 200MHz square wave, tR< 300ps, 8mVp-p.
Note 2:Input is a 200MHz square wave, tR< 300ps, 1.8Vp-p.
Note 3:Input-referred noise = RMS output noise/low-frequency gain.
Power Supply, VCC- VEE......................................................6.0V
Input Voltage, DIN+, DIN-.....................................................6.0V
CZN, CZP, ENB, VLOS, DIV2, LOS+, LOS-.....-0.3V, VCC+ 0.3V
DOUT+, DOUT- (with 50Ωload).......................2.5V, VCC+ 0.3V
Continuous Power Dissipation (TA= +70°C)
SSOP (derate 10mW/°C above +70°C)....................500mW°C
Junction Operating Temperature......................-55°C to +150°C
Storage Temperature Range.............................-55°C to +175°C
Processing Temperature (Die).........................................+400°C
MAX3262
1Gbps, High-Speed Limiting Amplifier with
Chatter-Free Loss-of-Signal Detection
__________________________________________Typical Operating Characteristics(VCC= 5V, TA = +25°C, unless otherwise noted.)
MAX3262
1Gbps, High-Speed Limiting Amplifier with
Chatter-Free Loss-of-Signal Detection
_______________________________________________________________Pin Description
_______________Detailed DescriptionThe MAX3262 is an integrated limiting amplifier intend-
ed for high-frequency fiber-optic applications. The cir-
cuit connects to typical transimpedance amplifiers
found within a fiber-optic link. The linear signal output
from a transimpedance amplifier can contain significant
amounts of noise, and may vary in amplitude over time.
The MAX3262 limiting amplifier quantizes the signal,
and outputs a voltage-limited waveform over a 48dB
input dynamic range.
The MAX3262 provides an offset correction function
that effectively reduces the offset voltage to negligible
levels. In communications systems using NRZ data with
a 50% duty cycle, pulse-width distortion present in the
signal or generated by the transimpedance amplifier
appears as input offset and is partially removed by the
offset correction function. An external capacitor is
required between CZP and CZN to compensate the off-
set correction loop, determining the lower 3dB point.
Loss-of-Signal FunctionThe MAX3262 incorporates a chatter-free loss-of-signal
function, which is used to detect that the input signal
has dropped below the level necessary for acceptable
bit error rate performance, or to indicate an open-fiber
condition. The loss-of-signal function is implemented
with a rectifying peak detector, which samples the sig-
nal entering the output stage. The output from the peak
detector is compared against an internally generated
threshold, and is used to assert the LOS+ and LOS-
outputs.
The loss-of-signal threshold is adjusted by varying the
amplifier gain. The MAX3262 is configurable for gains
between 33dB and 48dB, allowing LOS thresholds
between 9mVp-p and 48mVp-p. Figure 2 shows the
LOS threshold as a function of the DIV2 and VLOSpins.
The DIV2 pin provides a coarse adjustment of 6dB of
gain, while the VLOSpin provides a fine gain adjust-
ment between 0dB and 11dB.
MAX3262
1Gbps, High-Speed Limiting Amplifier with
Chatter-Free Loss-of-Signal DetectionFigure 1. Functional Diagram
MAX3262Level-detect hysteresis and a 200ns internal delay
ensure chatter-free LOS outputs when the input signal
level is close to the LOS threshold. The hysteresis for
any programmed loss-of-signal level is nominally 2.5dB.
The LOS+ and LOS- outputs are open-collector,
Schottky-clamped transistors, that require pull-up resis-
tors for proper operation (Figure 3). The loss-of-signal
time constant is set externally with the appropriate pull-up
resistor and shunt load capacitance.
The ENBpin allows the user to disable the output sig-
nal without removing the input signal.
Wire Bonding DieFor reliable operation, the MAX3262 has gold metaliza-
tion. Connections to the die should be made with gold
wire only, using ball bonding techniques. Wedge bond-
ing is not recommended. Bond pad size is 4 mils.
__________________Design Procedure
Determining Capacitor ValuesThe MAX3262 inputs must be AC coupled to allow prop-
er operation of the offset correction function. Figure 4
shows the circuit’s input stage. The circuit’s lower -3dB
point is determined by the input coupling capacitors. The
lower -3dB frequency is 1 / [(2π)(1500Ω)(CIN)] Hz.
CINshould be large enough to not affect the signal
quality, but small enough to not affect the LOS assert
time. When an open-fiber condition occurs, the input
coupling capacitors must discharge below the LOS
threshold level before the LOS can assert. The worst-
case discharge time would occur with the maximum
input signal and the minimum LOS threshold. In this
case, the input capacitor must discharge from 0.9V to
4.5mV. The time required for this to occur is:
t = (1500)(CIN) In(VMAX/ VTHRESH) seconds
Example: If the MAX3262 is configured for 6mV sensi-
tivity, CIN= 100pF results in a lower -3dB frequency of
1MHz, and a maximum LOS delay of about 1µs.
The offset correction capacitor (CAZ) must be greater
than 100nF to ensure stable operation. This capacitor is
in series with an internal 40kΩof resistance. The -3dB
point of the offset zeroing circuit is:
1 / [(2π)(CAZ)(40kΩ)] Hz
For CAZ= 180nF, the bandwidth of the offset correction
circuit is 22Hz. Maxim’s proprietary offset-correction
architecture decouples the input coupling time constant
from the offset correction time constant. This ensures
there is no interaction between these two networks, elimi-
nating an additional source of chatter on LOS.
1Gbps, High-Speed Limiting Amplifier with
Chatter-Free Loss-of-Signal DetectionFigure 2. MAX3262 Sensitivity vs. VLOSSetting
Figure 3. Setting the LOS Time Constant
