参数资料
| 型号： | DS1874T+ |
| 厂商： | Maxim Integrated |
| 文件页数： | 14/88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
BIAS and MODULATION Control
During Power-Up
The DS1874 has two internal registers, MODULATION
and BIAS, that represent the values written to the
MAX3798/MAX3799’s modulation DAC and bias DAC
through the 3-wire interface. On power-up, the DS1874
sets the MODULATION and BIAS registers to 0. When
V CC is above POA, the DS1874 initializes the MAX3798/
MAX3799. After a temperature conversion is completed
and if the VCC LO alarm is enabled, an additional V CC
conversion above the customer-defined VCC LO alarm
level is required before the MAX3798/MAX3799 MODU-
LATION register is updated with the value determined
by the temperature conversion and the modulation LUT.
When the MODULATION register is set, the BIAS regis-
ter is set to a value equal to ISTEP (see Figure 2). The
startup algorithm checks if this bias current causes a
feedback voltage above the APC set point, and if not, it
continues increasing the BIAS register by ISTEP until the
APC set point is exceeded. When the APC set point is
exceeded, the device begins a binary search to quickly
reach the bias current corresponding to the proper
power level. After the binary search is completed, the
APC integrator is enabled and single LSB steps are
used to tightly control the average power.
The TXP HI, TXP LO, HBAL, and BIAS MAX QT alarms
are masked until the binary search is completed.
However, the BIAS MAX alarm is monitored during this
time to prevent the BIAS register from exceeding
IBIASMAX. During the bias current initialization, the
BIAS register is not allowed to exceed IBIASMAX. If this
occurs during the ISTEP sequence, then the binary
search routine is enabled. If IBIASMAX is exceeded
during the binary search, the next smaller step is acti-
vated. ISTEP or binary increments that would cause the
BIAS register to exceed IBIASMAX are not taken.
Masking the alarms until the completion of the binary
search prevents false positive alarms during startup.
ISTEP is programmed by the customer using Table
02h, Register BBh. During the first steps, the MAX3798/
MAX3799 ’s bias DAC is directly written using
SET_IBIAS (3-wire address 09h). ISTEP should be pro-
grammed to the maximum safe increase that is allow-
able during startup. If this value is programmed too
low, the DS1874 still operates, but it could take signifi-
cantly longer for the algorithm to converge and hence
to control the average power.
If a fault is detected, and TXD is toggled to reenable
the outputs, the DS1874 powers up following a similar
sequence to an initial power-up. The only difference is
that the DS1874 already has determined the present
temperature, so the t INIT time is not required for the
DS1874 to recall the APC and MOD set points from
EEPROM.
V CC
V POA
t INIT
MODULATION REGISTER
t SEARCH
4x ISTEP
BIAS REGISTER
3x ISTEP
2x ISTEP
ISTEP
BINARY SEARCH
APC INTEGRATOR ON
BIAS SAMPLE
1
2
3
4
5
6
7
8
9
10
11
12
13
Figure 2. Power-Up Timing
14
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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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