IN 10kΩ INTERNAL SWITCH NETWORK 10kΩ " />
參數(shù)資料
型號: LTC2487CDE#PBF
廠商: Linear Technology
文件頁數(shù): 15/32頁
文件大?。?/td> 0K
描述: IC ADC 16BIT DELTA SIG 14-DFN
標準包裝: 91
位數(shù): 16
采樣率(每秒): 15
數(shù)據(jù)接口: I²C,串行
轉(zhuǎn)換器數(shù)目: 1
功率耗散(最大): 800µW
電壓電源: 單電源
工作溫度: 0°C ~ 70°C
安裝類型: 表面貼裝
封裝/外殼: 14-WFDFN 裸露焊盤
供應(yīng)商設(shè)備封裝: 14-DFN-EP(4x3)
包裝: 管件
輸入數(shù)目和類型: 4 個單端,雙極;2 個差分,雙極
配用: DC1010A-C-ND - BOARD DELTA SIGMA ADC LTC2487
LTC2487
22
2487fd
Figure 11. Equivalent Analog Input Circuit
IN+
IN
10kΩ
INTERNAL
SWITCH
NETWORK
10kΩ
CEQ
12μF
10kΩ
IIN
REF+
IREF
+
IIN
+
IREF
2487 F11
SWITCHING FREQUENCY
fSW = 123kHz INTERNAL OSCILLATOR
fSW = 0.4 fEOSC EXTERNAL OSCILLATOR
REF
10kΩ
100Ω
INPUT
MULTIPLEXER
100Ω
IIN+
()
AVG
= IIN
()
AVG
=
VIN(CM) VREF(CM)
0.5REQ
IREF+
()
AVG
1.5VREF + VREF(CM) –VIN(CM)
()
0.5 REQ
VIN
2
VREF REQ
where:
VREF =REF
+
REF
VREF(CM) =
REF+ –REF
2
VIN =IN
+ IN ,WHERE IN+ ANDIN ARE THE SELECTEDINPUT CHANNELS
VIN(CM) =
IN+ –IN
2
REQ = 2.71M INTERNAL OSCILLATOR 60Hz MODE
REQ = 2.98M INTERNAL OSCILLATOR 50Hz/60Hz MODE
REQ = 0.83310
12
()/fEOSC EXTERNALOSCILLATOR
Driving the Input and Reference
The input and reference pins of the LTC2487 are connected
directly to a switched capacitor network. Depending on
the relationship between the differential input voltage and
the differential reference voltage, these capacitors are
switched between these four pins. Each time a capacitor
is switched between two of these pins, a small amount
of charge is transferred. A simplied equivalent circuit is
shown in Figure 11.
When using the LTC2487’s internal oscillator, the input
capacitor array is switched at 123kHz. The effect of the
charge transfer depends on the circuitry driving the
input/reference pins. If the total external RC time constant
is less than 580ns the errors introduced by the sampling
process are negligible since complete settling occurs.
Typically, the reference inputs are driven from a low
impedance source. In this case, complete settling occurs
even with large external bypass capacitors. The inputs
(CH0-CH3, COM), on the other hand, are typically driven
from larger source resistances. Source resistances up
to 10k may interface directly to the LTC2487 and settle
completely; however, the addition of external capacitors
at the input terminals in order to lter unwanted noise
(antialiasing) results in incomplete settling.
Automatic Differential Input Current Cancellation
In applications where the sensor output impedance is
low (up to 10kΩ with no external bypass capacitor or up
to 500Ω with 0.001μF bypass), complete settling of the
input occurs. In this case, no errors are introduced and
direct digitization is possible.
APPLICATIONS INFORMATION
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LTC2488CDE#PBF 功能描述:IC ADC 16BIT DELTA SIG 14-DFN RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標準包裝:1 系列:microPOWER™ 位數(shù):8 采樣率(每秒):1M 數(shù)據(jù)接口:串行,SPI? 轉(zhuǎn)換器數(shù)目:1 功率耗散(最大):- 電壓電源:模擬和數(shù)字 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-VQFN 裸露焊盤(4x4) 包裝:Digi-Reel® 輸入數(shù)目和類型:8 個單端,單極 產(chǎn)品目錄頁面:892 (CN2011-ZH PDF) 其它名稱:296-25851-6
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