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参数资料
| 型号： | AD8436JCPZ-WP |
| 厂商： | Analog Devices Inc |
| 文件页数： | 13/24页 |
| 文件大小： | 0K |
| 描述： | IC CONV TRUE RMS-DC LP 20LFCSP |
| 产品培训模块： | Introduction to Analog RMS-to-DC Technology: Converters and Applications |
| 标准包装： | 64 |
| 电流 - 电源： | 325µA |
| 电源电压： | ±2.4 V ~ 18 V，4.8 V ~ 36 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-WFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 20-LFCSP-WQ（4x4） |
| 包装： | 托盘 - 晶粒 |
Data Sheet
For simplicity, Figure 29 shows ripple vs. frequency for four
combinations of CAVG and CLPF
AD8436
Basic Core Connections
Many applications require only a single external capacitor for
1
0.1
0.01
0.001
AC INPUT = 300mV rms
CAVG = 1μF, CLPF = 0.33μF
CAVG = 1μF, CLPF = 3.3μF
CAVG = 10μF, CLPF = 0.33μF
CAVG = 10μF, CLPF = 3.3μF
averaging. A 10 μF capacitor is more than adequate for acceptable
rms errors at line frequencies and below.
The signal source sees the input 8 kΩ voltage-to-current conversion
resistor at Pin RMS; thus, the ideal source impedance is a
voltage source (0 Ω source impedance). If a non-zero signal source
impedance cannot be avoided, be sure to account for any series
connected voltage drop.
An input coupling capacitor must be used to realize the near-zero
output offset voltage feature of the AD8436 . Select a coupling
4.7μF
0.0001
10 100 1k
INPUT FREQUENCY (Hz)
Figure 29. Residual Ripple Voltage for Various Filter Configurations
capacitors on transition and settling times using a 10-cycle,
50 Hz, 1 second period burst signal input to demonstrate time-
domain behavior. In this instance, the averaging capacitor value
was 10 μF, yielding a ripple value of 6 mV rms. A postconversion
capacitor (CLPF) of 0.68 μF reduced the ripple to 1 mV rms. An
averaging capacitor value of 82 μF reduced the ripple to 1 mV
capacitor value that is appropriate for the lowest expected
operating frequency of interest. As a rule of thumb, the input
coupling capacitor can be the same as or half the value of the
averaging capacitor because the time constants are similar. For
a 10 μF averaging capacitor, a 4.7 μF or 10 μF tantalum capacitor
+5V
CAVG
+*
10μF
19 17
CAVG VCC
OR 10μF
but extended the transition time (and cost) significantly.
+*
2
RMS
AD8436
OUT 9
IGND
VEE
OGND
INPUT
50Hz 10 CYCLE BURST
11
10
8
400mv/DIV
–5V
*FOR POLARIZED CAPACITOR STYLES.
CAVG = 10μF FOR BOTH PLOTS,
BUT RED PLOT HAS NO LOW-PASS FILTER,
GREEN PLOT HAS CLPF = 0.68μF
10mV/DIV
CAVG = 82μF
TIME (100ms/DIV)
Figure 31. Basic Applications Circuit
Using a Capacitor for High Crest Factor Applications
The AD8436 contains a unique feature to reduce large crest
factor errors. Crest factor is often overlooked when considering
the requirements of rms-to-dc converters, but it is very
important when working with signals with spikes or high peaks.
The crest factor is defined as the ratio of peak voltage to rms.
See Table 5 for crest factors for some common waveforms.
Figure 30. Effects of Various Filter Options on Transition Times
CAVG Capacitor Styles
CAVG
+*
10μF
+5V
CCF
When selecting a capacitor style for CAVG there are certain
tradeoffs.
19
18
0.1μF
17
For general usage, such as most DMM or power measurement
4.7μF
OR 10μF
CAVG
CCF
VCC
applications where input amplitudes are typically greater than
+*
2
RMS
AD8436
OUT 9
1 mV, surface mount tantalums are the best overall choice for
space, performance, and economy.
IGND
11
VEE
10
OGND
8
For input amplitudes less than around a millivolt, low dc leakage
capacitors, such as film or X8L MLCs, maintain rms conversion
accuracy. Metalized polyester or similar film styles are best, as
long as the temperature range is appropriate. X8L grade MLCs are
rated for high temperatures (125°C or 150°C), but are available only
up to 10 μF. Never use electrolytic capacitors, or X7R or lower grade
ceramics.
–5V
*FOR POLARIZED CAPACITOR STYLES.
Figure 32. Connection for Additional Crest Factor Performance
Crest factor performance is mostly applicable for unexpected
waveforms such as switching transients in switchmode power
supplies. In such applications, most of the energy is in these
peaks and can be destructive to the circuitry involved, although
the average ac value can be quite low.
Rev. B | Page 13 of 24
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD843A | 制造商:AD 制造商全称:Analog Devices 功能描述:34 MHz, CBFET Fast Settling Op Amp |
| AD843AQ | 功能描述:IC OPAMP GP 34MHZ 50MA 8CDIP RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:2,500 系列:Excalibur™ 放大器类型:J-FET 电路数:1 输出类型:- 转换速率:45 V/µs 增益带宽积:10MHz -3db带宽:- 电流 - 输入偏压:20pA 电压 - 输入偏移:490µV 电流 - 电源:1.7mA 电流 - 输出 / 通道:48mA 电压 - 电源，单路/双路(±):4.5 V ~ 38 V，±2.25 V ~ 19 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SOIC 包装:带卷 (TR) |
| AD843B | 制造商:AD 制造商全称:Analog Devices 功能描述:34 MHz, CBFET Fast Settling Op Amp |
| AD843BH | 制造商:Analog Devices 功能描述:OP Amp Single GP 制造商:Rochester Electronics LLC 功能描述:FAST SETTLING H.S. OP AMP - Bulk |
| AD843BHZ | 制造商:Analog Devices 功能描述:OP Amp Single GP 制造商:Analog Devices 功能描述:OP AMP SGL GP 18V 12PIN TO-8 - Rail/Tube |
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