参数资料
| 型号： | DS1874T+ |
| 厂商： | Maxim Integrated |
| 文件页数： | 17/88页 |
| 文件大小： | 0K |
| 描述： | IC CTLR SFP+ ANLG LDD 28-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 类型： | 激光二极管控制器 |
| 通道数： | 1 |
| 电源电压： | 2.85 V ~ 3.9 V |
| 电流 - 电源： | 2.5mA |
| 工作温度： | -40°C ~ 95°C |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（5x5） |
| 包装： | 管件 |
| 安装类型： | 表面贴装 |
| 其它名称： | 90-1874T+000 |
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SFP+ Controller with Digital LDD Interface
ONE ROUND-ROBIN ADC CYCLE
TEMP
V CC
MON1
MON2
MON3
MON4
TEMP
t RR
NOTE: IF THE VCC LO ALARM IS ENABLED AT POWER-UP, THE ADC ROUND-ROBIN TIMING CYCLES BETWEEN TEMPERATURE AND V CC ONLY UNTIL V CC
IS ABOVE THE V CC ALARM LOW THRESHOLD.
Figure 5. ADC Round-Robin Timing
range that benefits using right-shifting) and then automat-
ically disables right-shifting (recalling different gain and
V CC
offset settings) when the input signal exceeds the thresh-
MON3P
DS1874
old. Also, to prevent “chattering,” hysteresis prevents
excessive switching between modes in addition to ensur-
100 Ω
MON3N
ADC
ing that continuity is maintained. Dual-range operation is
enabled by default (factory programmed in EEPROM).
However, it can easily be disabled through the RSSI_FC
ROSA
Figure 6. MON3 Differential Input for High-Side RSSI
the measurement is increased by a factor of 8, and
because the result is digitally divided by 8 by right-
shifting, the bit weight of the measurement still meets
the standard’s specification (i.e., SFF-8472).
The right-shift operation on the ADC result is carried out
based on the contents of right-shift control registers (Table
02h, Registers 8Eh–8Fh) in EEPROM. Four analog chan-
nels, MON1–MON4, each have 3 bits allocated to set the
number of right-shifts. Up to seven right-shift operations
are allowed and are executed as a part of every conver-
sion before the results are compared to the high-alarm
and low-alarm levels, or loaded into their corresponding
measurement registers (Lower Memory, Registers
64h–6Bh). This is true during the setup of internal calibra-
tion as well as during subsequent data conversions.
Enhanced RSSI Monitoring (Dual-Range
Functionality)
The DS1874 offers a feature to improve the accuracy
and range of MON3, which is most commonly used for
monitoring RSSI. The accuracy of the RSSI measure-
ments is increased at the small cost of reduced range
(of input signal swing). The DS1874 eliminates this
trade-off by offering “dual range” calibration on the
MON3 channel (see Figure 6). This feature enables
right-shifting (along with its gain and offset settings)
when the input signal is below a set threshold (within the
and RSSI_FF bits, which are described in the Register
Descriptions section. When dual-range operation is dis-
abled, MON3 operates identically to the other MON
channels, although featuring a differential input.
Dual-range functionality consists of two modes of opera-
tion: fine mode and coarse mode. Each mode is calibrat-
ed for a unique transfer function, hence the term, dual
range. Table 5 highlights the registers related to MON3.
Fine mode is equivalent to the other MON channels. Fine
mode is calibrated using the gain, offset, and right-shift-
ing registers at locations shown in Table 5 and is ideal
for relatively small analog input voltages. Coarse mode is
automatically switched to when the input exceeds a
threshold (to be discussed in a subsequent paragraph).
Coarse mode is calibrated using different gain and offset
registers, but lacks right-shifting (since coarse mode is
only used on large input signals). The gain and offset
registers for coarse mode are also shown in Table 5.
Additional information for each of the registers can be
found in the Register Descriptions section.
Dual-range operation is transparent to the end user.
The results of MON3 analog-to-digital conversions are
still stored/reported in the same memory locations
(68h–69h, Lower Memory) regardless of whether the
conversion was performed in fine mode or coarse
mode. The only way to tell which mode generated the
digital result is by reading the RSSIR bit.
When the DS1874 is powered up, analog-to-digital con-
versions begin in a round-robin fashion. Every MON3
timeslice begins with a fine mode analog-to-digital con-
version (using fine mode’s gain, offset, and right-shifting
settings). See the flowchart in Figure 7 for more details.
______________________________________________________________________________________
17
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相关代理商/技术参数 |
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| DS1874T+ | 功能描述:ADC / DAC多通道 SFP+ Controller w/ Dgtl LDD Interface RoHS:否 制造商:Texas Instruments 转换速率: 分辨率:8 bit 接口类型:SPI 电压参考: 电源电压-最大:3.6 V 电源电压-最小:2 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-40 |
| DS1874T+T&R | 制造商:Maxim Integrated Products 功能描述:SFP+ CONTROLLER WITH DIGITAL LDD INTERFACE - Tape and Reel 制造商:Maxim Integrated Products 功能描述:MXMDS1874T+T&R SFP+ CTRLR FOR USE W/MAX3 制造商:Maxim Integrated Products 功能描述:IC CTLR SFP+ ANLG LDD 28-TQFN |
| DS1874T+T&R | 功能描述:ADC / DAC多通道 SFP+ Controller w/ Dgtl LDD Interface RoHS:否 制造商:Texas Instruments 转换速率: 分辨率:8 bit 接口类型:SPI 电压参考: 电源电压-最大:3.6 V 电源电压-最小:2 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-40 |
| DS1874T+TR | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:SFP+ Controller with Digital LDD Interface |
| DS1875 | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:PON Triplexer and SFP Controller |
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