参数资料
| 型号： | ADL5304ACPZ-RL |
| 厂商： | Analog Devices Inc |
| 文件页数： | 14/32页 |
| 文件大小： | 0K |
| 描述： | IC AMP LOG CONV 32LFCSP |
| 标准包装： | 5,000 |
| 类型： | 对数转换器 |
| 应用： | 光纤 |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-VFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 32-LFCSP-VQ（5x5） |
| 包装： | 带卷 (TR) |
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Data Sheet
ADL5304
Rev. 0 | Page 21 of 32
Capacitor, C1D, effectively reduces the bandwidth of the
denominator input stage. A few picofarads of capacitance
(<5 pF) reduce the bandwidth significantly for currents below
approximately 1 μA, though whereas 1 nF to 10 nF are normally
enough to reduce the bandwidth up to the maximum 10 mA of
input current. When measurement speed is of primary importance,
it is better to add filtering after the FET amp outputs, in which
case, C2D, RD, and C3D are the best locations. The resistor in this
case should not be much larger than 1 kΩ because there is a
bias current that is approximately 35 μA that flows from the
temperature compensation block into each of the VDEN and
VNUM pins. Inserting a resistor, as shown in Figure 48, lifts up
the voltages at the INNM and/or INDN pins and potentially causes
headroom problems in the temperature compensation block.
When IDEN is used as the reference, as is normally done, then it
is recommended that C1D is zero, C2D is a 0.1 μF ceramic
decoupling capacitor, RD is a short, and C3D is not placed.
Adding a capacitor, CFB, adds additional filtering at the buffer
output. This capacitor also helps to optimize the pulse response
by placing a zero across the feedback resistor (2.5 kΩ in the
default configuration). A good value to start with is 22 pF, this
introduces a zero at 2.9 MHz that can improve the pulse responses
for input currents above approximately 100 μA.
Photodiode Bias
The ADL5304 provides for adaptive photodiode bias. A monitoring
transistor, Q3, connected in parallel with Q1 (see Figure 49),
samples 1/10th the input current, INUM. This sampled current is
multiplied by a factor of 11 to give an effective output current at
the IMON pin of 1.1 times INUM. Because the photodiode produces
INUM, the additional current has to flow in an external resistor,
RMNTR, equal to 10 × RS, where RS is the value of the internal
parasitic series resistance of the photodiode. This ensures that
the actual junction of the photodiode is biased as close as
possible to 0 V to minimize dark current. Capacitor, CMON,
provides potential filtering and dynamic currents during fast
transients. The value for best bias response depends on the
photodiode used and should be determined experimentally.
Nominally, CMON = 0.
If the adaptive bias is not used, the IMON pin must be connected
to ground. It is easy to provide a 0.5 V reverse bias across the
diode by using the 2VLT reference and connecting it to the
cathode. Because the ADL5304 forces the voltage at INUM very
close to 1.500 V, the trimmed 2.000 V ensures a precise 0.5 V
reverse bias for the PD.
09
459
-058
MONITOR AND
PD BIAS
(1.1× INUM)
2
3
4
5
6
8
7
30
VSM2
VSM1
RMNTR
32
VSM3
VSM4
IREF
IDEN
INUM
100nA
Q2
Q1
Q3
1.5V
9
VDEN
VNUM
IMON
SHIELD
PD
CMON
FROM 1.5V VREF
Figure 49. Adaptive Photodiode Bias
One example of dual-supply operation is shown in Figure 50, where
the 2.000 V (the 2VLT pin) reference ensures a precisely controlled,
reverse bias across the PD. The user can use other reverse bias
voltages but needs to provide them separately. Note that when the
VSMx pins are grounded, the DCBI and INPS pins must also be
grounded.
09
45
9-
1
50
MONITOR AND
PD BIAS
(1.1× INUM)
2
3
4
5
6
8
7
30
VSM2
VSM1
32
VSM3
VSM4
IREF
IDEN
INUM
100nA
Q2
Q1
Q3
9
VDEN
VNUM
IMON
SHIELD
PD
FROM 2.0V
VREF
Figure 50. PD Bias with VSUM at Ground and Using 2.000 V
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| ADL5304-EVALZ | 功能描述:BOARD EVAL FOR ADL5304A RoHS:是 类别:编程器，开发系统 >> 评估演示板和套件 系列:* 标准包装:1 系列:- 主要目的:电信，线路接口单元（LIU） 嵌入式:- 已用 IC / 零件:IDT82V2081 主要属性:T1/J1/E1 LIU 次要属性:- 已供物品:板，电源，线缆，CD 其它名称:82EBV2081 |
| ADL5305ACP-REEL | 制造商:Analog Devices 功能描述:LOGARITHMIC CONVERTER - Tape and Reel |
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| ADL5306ACP-R2 | 功能描述:IC CONVERT LOGARITH 60DB 16LFCSP RoHS:否 类别:集成电路 (IC) >> 线性 - 放大器 - 专用 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:60 系列:- 类型:可变增益放大器 应用:CATV 安装类型:表面贴装 封装/外壳:20-WQFN 裸露焊盘 供应商设备封装:20-TQFN-EP（5x5） 包装:托盘 |
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