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參數(shù)資料
| 型號： | MAX3762EEP |
| 廠商： | Maxim Integrated Products |
| 文件頁數(shù)： | 10/12頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC AMP LIMITING 622MBPS 20-QSOP |
| 產(chǎn)品培訓模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標準包裝： | 50 |
| 類型： | 限幅放大器 |
| 應用： | 光纖學網(wǎng)絡 |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 20-SSOP（0.154"，3.90mm 寬） |
| 供應商設備封裝： | 20-QSOP |
| 包裝： | 管件 |
Loss-of-Signal Indicator
The MAX3761/MAX3762 includes a loss-of-signal moni-
tor with a programmable assert threshold and a hys-
teresis comparator. Internally, one comparator input is
tied to the RSSI output signal and the other is tied to the
threshold-voltage (VTH) pin, which provides a threshold
for the LOS indication. An op amp referenced to an
internal bandgap voltage (1.18V) is supplied for pro-
gramming a supply-independent threshold voltage.
Only two external resistors are needed to program the
LOS assert level. VTH is programmable from 1.18V to
2.4V, providing adequate coverage of the RSSI output’s
useful range. The op amp runs on very low supply cur-
rent and provides an accurate, temperature-stable
threshold, but can source only 20μA of current. For
proper operation, resistor R1 (see the
Typical
Operating Circuit) should have a value
≥ 100kΩ. The
input bias current at INV is < 50nA.
To ensure chatter-free LOS operation, the internal LOS
comparator contains approximately 90mV of hysteresis.
The RSSI signal output has a slope of 25mV/dB.
Therefore, the overall circuit hysteresis is approximately
3.6dB[90mV / (25mV/dB)]. The LOS assert threshold is
45mV below VTH, while the LOS deassert threshold is
45mV above VTH.
Output Buffers
The DISABLE pin can be used to disable the data-
output buffer. When DISABLE is high, the differential
output signal at OUT+ and OUT- is approximately zero.
In the disabled state, the common-mode voltage of
each output is approximately VCC - 0.8V. Connecting
DISABLE to LOS+ implements a squelch function. When
using the squelch function, the output signal is disabled
whenever the input signal is too small to be reliably
detected (as determined by the voltage at VTH). Use of
the disable function is recommended at all times.
The data outputs (OUT+ and OUT-) are implemented
with emitter followers that have output impedance of
approximately 2
Ω. The MAX3762’s PECL LOS outputs
also are implemented with emitter followers that have
output impedance of approximately 2
Ω.
The MAX3761 TTL LOS output buffers are open-collec-
tor transistors with 6k
Ω internal pull-up resistors.
__________________Design Procedure
Supply Voltage
The MAX3761/MAX3762 can be operated with a single
+5V or -5V power supply.
Programming the LOS Assert Level
First determine the receiver system’s sensitivity in dBm
either by estimating or from prototyping results.
Estimate the total gain of the preamplifier and photodi-
ode, then use Figure 3 to select resistor R2, placing the
LOS assert 3dB to 4dB below the receiver sensitivity.
Alternatively, use the
Typical Operating Characteristics
to select the VTH value needed for LOS assert, then
program VTH with the following relation:
VTH = 1.18(1 + R2 / R1)
Select R1
≥ 100kΩ.
MAX3761/MAX3762
Low-Power, 622Mbps Limiting Amplifiers
with Chatter-Free Power Detect for LANs
_______________________________________________________________________________________
7
VASSERT (min)
VASSERT
VDEASSERT (max)
VDEASSERT
VTH
1.2V
45mV
25mV/dB
45mV
INPUT SIGNAL AMPLITUDE
RSSI
VOLTAGE
3.6dB
typical
Figure 2. Loss-of-Signal Definitions
0
-38
-36
-28
-22
10
60
70
MAX3761/2-03
INPUT SIGNAL (dBm)
VALUE
OF
R2
(k
Ω
)
-32
-34
-26
-30
-24
40
20
80
50
30
GAIN = 2000
GAIN = 6000
R1 = 100k
Ω
GAIN = 4000
Figure 3. Using TIA Gain and Photodiode Responsivity to
Select LOS Programming Resistor
GAIN IS PHOTODIODE RESPONSIVITY x TRANSIMPEDANCE GAIN.
EXTINCTION RATIO OF 10 IS ASSUMED.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX3762EEP+ | 功能描述:限幅放大器 622Mbps w/Chatter Free Power Detect RoHS:否 制造商:Micrel 輸入電壓范圍（最大值）:3.6 V 工作電源電壓:3.3 V 電源電流:40 mA 工作溫度范圍:- 40 C to + 85 C 封裝 / 箱體:MSOP-10 封裝:Tube |
| MAX3762EEP+T | 功能描述:限幅放大器 622Mbps w/Chatter Free Power Detect RoHS:否 制造商:Micrel 輸入電壓范圍（最大值）:3.6 V 工作電源電壓:3.3 V 電源電流:40 mA 工作溫度范圍:- 40 C to + 85 C 封裝 / 箱體:MSOP-10 封裝:Tube |
| MAX3762EEP-T | 功能描述:限幅放大器 622Mbps w/Chatter Free Power Detect RoHS:否 制造商:Micrel 輸入電壓范圍（最大值）:3.6 V 工作電源電壓:3.3 V 電源電流:40 mA 工作溫度范圍:- 40 C to + 85 C 封裝 / 箱體:MSOP-10 封裝:Tube |
| MAX3762EVKIT-SO | 功能描述:限幅放大器 Evaluation Kit for the MAX3762 RoHS:否 制造商:Micrel 輸入電壓范圍（最大值）:3.6 V 工作電源電壓:3.3 V 電源電流:40 mA 工作溫度范圍:- 40 C to + 85 C 封裝 / 箱體:MSOP-10 封裝:Tube |
| MAX3765CUB | 功能描述:特殊用途放大器 RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
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