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參數(shù)資料
| 型號(hào)： | LTC1966MPMS8#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 模擬專用變換器 |
| 英文描述： | RMS TO DC CONVERTER, PDSO8 |
| 封裝： | LEAD FREE, PLASTIC, MSOP-8 |
| 文件頁數(shù)： | 5/38頁 |
| 文件大?。?/td> | 387K |
| 代理商： | LTC1966MPMS8#TRPBF |
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LTC1966
13
1966fb
applicaTions inForMaTion
DESIGN COOKBOOK
The LTC1966 RMS-to-DC converter makes it easy to
implement a rather quirky function. For many applications
all that will be needed is a single capacitor for averaging,
appropriate selection of the I/O connections and power
supply bypassing. Of course, the LTC1966 also requires
power. A wide variety of power supply configurations are
shown in the Typical Applications section towards the end
of this data sheet.
Capacitor Value Selection
The RMS or root-mean-squared value of a signal, the root
of the mean of the square, cannot be computed without
some averaging to obtain the mean function. The LTC1966
true RMS-to-DC converter utilizes a single capacitor on
the output to do the low frequency averaging required for
RMS-to-DC conversion. To give an accurate measure of a
dynamic waveform, the averaging must take place over a
sufficiently long interval to average, rather than track, the
lowest frequency signals of interest. For a single averag-
ing capacitor, the accuracy at low frequencies is depicted
in Figure 6.
Figure 6 depicts the so-called DC error that results at a
given combination of input frequency and filter capacitor
values1. It is appropriate for most applications, in which
the output is fed to a circuit with an inherently band lim-
ited frequency response, such as a dual slope/integrating
A/D converter, a
S A/D converter or even a mechanical
analog meter.
Figure 6. DC Error vs Input Frequency
Figure 7. Output Ripple Exceeds DC Error
However, if the output is examined on an oscilloscope
with a very low frequency input, the incomplete averag-
ing will be seen, and this ripple will be larger than the
error depicted in Figure 6. Such an output is depicted in
Figure7. The ripple is at twice the frequency of the input
because of the computation of the square of the input.
The typical values shown, 5% peak ripple with 0.05% DC
error, occur with CAVE = 1F and fINPUT = 10Hz.
If the application calls for the output of the LTC1966 to feed
asamplingorNyquistA/Dconverter(orothercircuitrythat
will not average out this double frequency ripple) a larger
averaging capacitor can be used. This trade-off is depicted
in Figure 8. The peak ripple error can also be reduced by
additional lowpass filtering after the LTC1966, but the
simplest solution is to use a larger averaging capacitor.
1This frequency dependent error is in addition to the static errors that affect all readings and are
therefore easy to trim or calibrate out. The Error Analyses section to follow discusses the effect
of static error terms.
C = 4.7F
INPUT FREQUENCY (Hz)
1
–2.0
DC
ERROR
(%)
–1.6
–1.2
–0.8
–0.4
10
20
50
60
100
1966 F06
0
–1.8
–1.4
–1.0
–0.6
–0.2
C = 10F
C = 2.2F
C = 1.0F
C = 0.47F
C = 0.22F
C = 0.1F
TIME
OUTPUT
1966 F07
DC
ERROR
(0.05%)
IDEAL
OUTPUT
DC
AVERAGE
OF ACTUAL
OUTPUT
PEAK
RIPPLE
(5%)
ACTUAL OUTPUT
WITH RIPPLE
f = 2 × fINPUT
PEAK
ERROR =
DC ERROR +
PEAK RIPPLE
(5.05%)
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| LTC1967CMS8 | 功能描述:IC CONVERTER RMS-DC PREC 8MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - RMS 至 DC 轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:46 系列:- 電流 - 電源:1.2mA 電源電壓:±18 V，36 V 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:16-SOIC W 包裝:管件 |
| LTC1967CMS8#PBF | 功能描述:IC CONVERTER RMS-DC PREC 8MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - RMS 至 DC 轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:46 系列:- 電流 - 電源:1.2mA 電源電壓:±18 V，36 V 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:16-SOIC W 包裝:管件 |
| LTC1967CMS8#TR | 功能描述:IC CONVERTER RMS-DC PREC 8MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - RMS 至 DC 轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:46 系列:- 電流 - 電源:1.2mA 電源電壓:±18 V，36 V 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:16-SOIC W 包裝:管件 |
| LTC1967CMS8#TRPBF | 功能描述:IC CONVERTER RMS-DC PREC 8MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - RMS 至 DC 轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:46 系列:- 電流 - 電源:1.2mA 電源電壓:±18 V，36 V 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:16-SOIC W 包裝:管件 |
| LTC1967CMS8PBF | 制造商:Linear Technology 功能描述:RMS-DC converter, LTC1967 40kHz MSOP |
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