- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄1899 > ADN2850BCPZ25-RL7 (Analog Devices Inc)IC DGTL RHEO DL 25K 9BIT16LFCSP PDF資料下載
參數(shù)資料
| 型號(hào)： | ADN2850BCPZ25-RL7 |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 15/28頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC DGTL RHEO DL 25K 9BIT16LFCSP |
| 產(chǎn)品變化通告： | Metal Edit Change 03/Feb/2012 |
| 標(biāo)準(zhǔn)包裝： | 1,500 |
| 接片： | 1024 |
| 電阻（歐姆）： | 25k |
| 電路數(shù)： | 2 |
| 溫度系數(shù)： | 標(biāo)準(zhǔn)值 35 ppm/°C |
| 存儲(chǔ)器類型： | 非易失 |
| 接口： | 4 線 SPI（芯片選擇） |
| 電源電壓： | 3 V ~ 5.5 V，±2.25 V ~ 2.75 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 16-VQFN 裸露焊盤，CSP |
| 供應(yīng)商設(shè)備封裝： | 16-LFCSP |
| 包裝： | 帶卷 (TR) |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁當(dāng)前第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁
ADN2850
Data Sheet
Rev. E | Page 22 of 28
At the resonant frequency, fO, the overall phase shift is zero, and
the positive feedback causes the circuit to oscillate. With R = R
',
C = C
', and R2 = R2A /(R2B + RDIODE), the oscillation frequency is
RC
O
1
=
ω
or
RC
fO
π
=
2
1
(13)
where R is equal to RWA such that :
W
NOM
WB
R
D
R
+
×
=
_
1024
)
(
(14)
At resonance, setting R2/R1 = 2 balances the bridge. In practice,
R2/R1 should be set slightly larger than 2 to ensure that the
oscillation can start. On the other hand, the alternate turn-on
of the diodes, D1 and D2, ensures that R2/R1 is smaller than 2,
momentarily stabilizing the oscillation.
When the frequency is set, the oscillation amplitude can be
turned by R2B because
D
O
V
I
V
+
=
R2B
3
2
(15)
VO, ID, and VD are interdependent variables. With proper
selection of R2B, an equilibrium is reached such that VO
converges. R2B can be in series with a discrete resistor to
increase the amplitude, but the total resistance cannot be too
large to saturate the output.
In Figure 35 and Figure 36, the frequency tuning requires that
both RDACs be adjusted concurrently to the same settings.
Because the two channels might be adjusted one at a time, an
intermediate state occurs that might not be acceptable for some
applications. Of course, the increment/decrement instructions
(Instruction 5, Instruction 7, Instruction 13, and Instruction 15)
can all be used. Different devices can also be used in daisy-chain
mode so that parts can be programmed to the same settings
simultaneously.
OPTICAL TRANSMITTER CALIBRATION WITH
ADN2841
The ADN2850, together with the multirate 2.7 Gbps laser diode
driver, ADN2841, forms an optical supervisory system in which
the dual digital resistor can be used to set the laser average optical
power and extinction ratio (see Figure 37). The ADN2850 is
particularly suited for the optical parameter settings because of
its high resolution and superior temperature coefficient
characteristics.
CS
CLK
SDI
W1
B1
EEMEM
ADN2841
PSET
ERSET
IMODP
IBIAS
IMPD
D
A
T
A
P
D
A
T
A
N
C
L
K
P
C
L
K
N
CLKN
CLKP
DATAP
DATAN
W2
B2
EEMEM
CONTROL
ADN2850
VCC
RDAC1
RDAC2
0
2
6
0
-0
5
7
Figure 37. Optical Supervisory System
The ADN2841 is a 2.7 Gbps laser diode driver that uses a
unique control algorithm to manage the average power and
extinction ratio of the laser after its initial factory calibration.
The ADN2841 stabilizes the data transmission of the laser by
continuously monitoring its optical power and correcting the
variations caused by temperature and the degradation of the
laser over time. In the ADN2841, the IMPD monitors the laser
diode current. Through its dual-loop power and extinction
ratio control calibrated by the dual RDACs of the ADN2850, the
internal driver controls the bias current, IBIAS, and consequently
the average power. It also regulates the modulation current,
IMODP, by changing the modulation current linearly with slope
efficiency. Therefore, any changes in the laser threshold current or
slope efficiency are compensated for. As a result, the optical
supervisory system minimizes the laser characterization efforts
and, therefore, enables designers to apply comparable lasers
from multiple sources.
INCOMING OPTICAL POWER MONITORING
The ADN2850 comes with a pair of matched diode connected
PNPs, Q1 and Q2, that can be used to configure an incoming
optical power monitoring function. With a reference current
source, an instrumentation amplifier, this feature can be used to
monitor the optical power by knowing the dc average photodiode
current from the following relationships:
1
ln
S
C
T
BE
I
V
=
(16)
2
ln
S
C
T
BE
I
V
=
(17)
Knowing IC1 = α1 × IPD, IC2 = α2 x IREF, and Q1-Q2 are matched,
therefore α and IS are matched. Combining Equation 16 and
Equation 17 theoretically yields:
PD
REF
T
I
V
ln
1
2
=
(18)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADN2860ACPZ250-RL7 | IC POT DGTL 3CH 250K 24-LFCSP |
| ADN4600ACPZ | IC CROSSPOINT SWITCH 8X8 64LFCSP |
| ADN4604ASVZ-RL | IC CROSSPOINT SWIT 16X16 100TQFP |
| ADN4605ABPZ | IC CROSSPOINT SWITCH 352BGA |
| ADN4661BRZ-REEL7 | IC DRIVER DIFF LVDS 1CH 8SOIC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADN2850BRU25 | 制造商:Analog Devices 功能描述: |
| adn2850bru25-rl7 | 制造商:Analog Devices 功能描述: |
| ADN2850BRUZ25 | 制造商:Analog Devices 功能描述:DUAL 9-BIT SPI DIG. POT - Rail/Tube 制造商:Analog Devices 功能描述:Dual 10-B Progable Non-Volatile Resistor |
| ADN2850BRUZ25-RL7 | 制造商:Analog Devices 功能描述: |
| ADN2855ACPZ | 功能描述:IC CLK DATA REC GPON 200MHZ 制造商:analog devices inc. 系列:- 包裝:托盤 零件狀態(tài):有效 PLL:是 主要用途:GPON，BPON，GEPON 輸入:CML 輸出:LVDS 電路數(shù):1 比率 - 輸入:輸出:1:1 差分 - 輸入:輸出:是/是 頻率 - 最大值:200MHz 電壓 - 電源:3 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:32-VFQFN 裸露焊盤，CSP 供應(yīng)商器件封裝:32-LFCSP-VQ（5x5） 標(biāo)準(zhǔn)包裝:1 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。