參數(shù)資料
型號(hào)： LTC1966
廠商： Linear Technology Corporation
英文描述： Precision Micropower, SIGMA RMS-to-DC Converter
中文描述： 精密微，適馬有效值- DC轉(zhuǎn)換器
文件頁(yè)數(shù)： 10/32頁(yè)
文件大小： 444K
代理商： LTC1966
10
LTC1966
sn1966 1966fas
The last two entries of Table 1 are chopped sine waves as
is commonly created with thyristors such as SCRs and
Triacs. Figure 2a shows a typical circuit and Figure 2b
shows the resulting load voltage, switch voltage and load
currents. The power delivered to the load depends on the
firing angle, as well as any parasitic losses such as switch
“ON” voltage drop. Real circuit waveforms will also typi-
cally have significant ringing at the switching transition,
dependent on exact circuit parasitics. For the purposes of
this data sheet, “SCR Waveforms” refers to the ideal
chopped sine wave, though the LTC1966 will do faithful
RMS-to-DC conversion with real SCR waveforms as well.
The case shown is for
Θ
= 90
°
, which corresponds to 50%
of available power being delivered to the load. As noted in
Table 1, when
Θ
= 114
°
, only 25% of the available power
is being delivered to the load and the power drops quickly
as
Θ
approaches 180
°
.
With an average rectification scheme and the typical
calibration to compensate for errors with sine waves, the
RMS level of an input sine wave is properly reported; it is
only with a non-sinusoidal waveform that errors occur.
Because of this calibration, and the output reading in
V
RMS
, the term True-RMS got coined to denote the use of
an actual RMS-to-DC converter as opposed to a calibrated
average rectifier.
APPLICATIOU
RMS-TO-DC CONVERSION
W
U
U
Definition of RMS
RMS amplitude is the consistent, fair and standard way to
measure and compare dynamic signals of all shapes and
sizes. Simply stated, the RMS amplitude is the heating
potential of a dynamic waveform. A 1V
RMS
AC waveform
will generate the same heat in a resistive load as will 1V DC.
+
R
1V DC
R
1966 F01
SAME
HEAT
1V AC
RMS
R
1V (AC + DC) RMS
Figure 1
Mathematically, RMS is the “Root of the Mean of the
Square:”
V
V
RMS
=
2
Alternatives to RMS
Other ways to quantify dynamic waveforms include peak
detection and average rectification. In both cases, an
average (DC) value results, but the value is only accurate
at the one chosen waveform type for which it is calibrated,
typically sine waves. The errors with average rectification
are shown in Table 1. Peak detection is worse in all cases
and is rarely used.
Table 1. Errors with Average Rectification vs True RMS
AVERAGE
RECTIFIED
(V)
1.000
0.900
0.866
0.637
WAVEFORM
Square Wave
Sine Wave
Triangle Wave
SCR at 1/2 Power,
Θ
= 90
°
SCR at 1/4 Power,
Θ
= 114
°
V
RMS
1.000
1.000
1.000
1.000
ERROR*
11%
*Calibrate for 0% Error
–3.8%
–29.3%
1.000
0.536
–40.4%
CONTROL
V
LOAD
AC
MAINS
V
LINE
–
V
THY
1966 F02a
+
+
+
–
–
I
LOAD
V
LINE
Θ
V
LOAD
V
THY
I
LOAD
1966 F02b
Figure 2a
Figure 2b
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC1966CMS8 功能描述:IC PREC RMS/DC CONV MCRPWR 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
LTC1966CMS8#PBF 功能描述:IC PREC RMS/DC CONV MCRPWR 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
LTC1966CMS8#TR 功能描述:IC PREC RMS/DC CONV MCRPWR 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
LTC1966CMS8#TRPBF 功能描述:IC PREC RMS/DC CONV MCRPWR 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
LTC1966CMS8PBF 制造商:Linear Technology 功能描述:RMS-to-DC Converter Prec. uPower MSOP8
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