參數(shù)資料
型號(hào)： LTC2494IUHF#TRPBF
廠商： Linear Technology
文件頁(yè)數(shù)： 24/38頁(yè)
文件大?。?/td> 0K
描述： IC ADC 16BIT W/PGA 38-QFN
標(biāo)準(zhǔn)包裝： 2,500
位數(shù)： 16
采樣率（每秒）： 15
數(shù)據(jù)接口： MICROWIRE?，串行，SPI?
轉(zhuǎn)換器數(shù)目： 1
功率耗散（最大）： 480µW
電壓電源： 單電源
工作溫度： -40°C ~ 85°C
安裝類型： 表面貼裝
封裝/外殼： 38-WFQFN 裸露焊盤
供應(yīng)商設(shè)備封裝： 38-QFN（5x7）
包裝： 帶卷 (TR)
輸入數(shù)目和類型： 16 個(gè)單端，雙極；8 個(gè)差分，雙極
配用： DC1011A-C-ND - BOARD DELTA SIGMA ADC LTC2494
LTC2494
0
2494fd
Figure 13. External Buffers Provide High Impedance Inputs and
Amplifier Offsets are Automatically Cancelled.
applications inForMation
difference between VIN(CM) and VREF(CM). For a reference
commonmodevoltageof2.5Vandaninputcommonmode
of 1.5V, the common mode input current is approximately
0.74A (in simultaneous 50Hz/60Hz rejection mode). This
commonmodeinputcurrentdoesnotdegradetheaccuracy
if the source impedances tied to IN+ and IN– are matched.
Mismatches in source impedance lead to a fixed offset
error but do not effect the linearity or full-scale reading.
A 1% mismatch in a 1k source resistance leads to a 74V
shift in offset voltage.
In applications where the common mode input voltage
varies as a function of the input signal level (single-ended
type sensors), the common mode input current varies
proportionally with input voltage. For the case of balanced
inputimpedances,thecommonmodeinputcurrenteffects
are rejected by the large CMRR of the LTC2494, leading
to little degradation in accuracy. Mismatches in source
impedances lead to gain errors proportional to the dif-
ference between the common mode input and common
mode reference. 1% mismatches in 1k source resistances
lead to gain errors on the order of 15ppm. Based on the
stability of the internal sampling capacitors and the ac-
curacy of the internal oscillator, a one-time calibration will
remove this error.
–
+
–
+
1/2 LTC6078
1
2
3
5
6
7
ADC
WITH
EASY DRIVE
INPUTS
INPUT
MUX
MUXOUTP
MUXOUTN
17
2494 F13
LTC2494
ANALOG
INPUTS
SDI
SCK
SDO
CS
1k
0.1F
In addition to the input sampling current, the input ESD
protection diodes have a temperature dependent leakage
current. This current, nominally 1nA (±10nA max) results
in a small offset shift. A 1k source resistance will create a
1V typical and a 10V maximum offset voltage.
Automatic Offset Calibration of External Buffers/
Amplifiers
In addition to the Easy Drive input current cancellation,
the LTC2494 enables an external amplifier to be inserted
between the multiplexer output and the ADC input (see
Figure 13). This is useful in applications where balanced
source impedances are not possible. One pair of external
buffers/amplifiers can be shared between all 17 analog
inputs.TheLTC2494performsaninternaloffsetcalibration
every conversion cycle in order to remove the offset and
drift of the ADC. This calibration is performed through a
combination of front end switching and digital process-
ing. Since the external amplifier is placed between the
multiplexer and the ADC, it is inside this correction loop.
This results in automatic offset correction and offset drift
removal of the external amplifier.
The LTC6078 is an excellent amplifier for this function.
It operates with supply voltages as low as 2.7V and its
noise level is 18nV/√Hz. The Easy Drive input technology
of the LTC2494 enables an RC network to be added directly
to the output of the LTC6078. The capacitor reduces the
magnitude of the current spikes seen at the input to the
ADC and the resistor isolates the capacitor load from the
op-amp output enabling stable operation.
Reference Current
Similar to the analog inputs, the LTC2494 samples the
differential reference pins (REF+ and REF–) transferring
small amounts of charge to and from these pins, thus
producing a dynamic reference current. If incomplete set-
tling occurs (as a function the reference source resistance
andreferencebypasscapacitance)linearityandgainerrors
are introduced.
For relatively small values of external reference capaci-
tance (CREF < 1nF), the voltage on the sampling capacitor
settles for reference impedances of many k
Ω (if CREF =
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LTC2495CUHF 制造商:Linear Technology 功能描述:ADC Single Delta-Sigma 15sps 16-bit Serial 38-Pin QFN EP
LTC2495CUHF#PBF 功能描述:IC ADC 16BIT W/PGA 38-QFN 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(biāo)準(zhǔn)包裝:1,000 系列:- 位數(shù):16 采樣率（每秒）:45k 數(shù)據(jù)接口:串行 轉(zhuǎn)換器數(shù)目:2 功率耗散（最大）:315mW 電壓電源:模擬和數(shù)字 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:28-SOIC W 包裝:帶卷 (TR) 輸入數(shù)目和類型:2 個(gè)單端，單極
LTC2495CUHF#TRPBF 功能描述:IC ADC 16BIT W/PGA 38-QFN 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(biāo)準(zhǔn)包裝:2,500 系列:- 位數(shù):16 采樣率（每秒）:15 數(shù)據(jù)接口:MICROWIRE?，串行，SPI? 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:480µW 電壓電源:單電源 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:38-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:38-QFN（5x7） 包裝:帶卷 (TR) 輸入數(shù)目和類型:16 個(gè)單端，雙極；8 個(gè)差分，雙極 配用:DC1011A-C-ND - BOARD DELTA SIGMA ADC LTC2494
LTC2495IUHF#PBF 功能描述:IC ADC 16BIT W/PGA 38-QFN 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(biāo)準(zhǔn)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(gè)單端，單極 產(chǎn)品目錄頁(yè)面:892 (CN2011-ZH PDF) 其它名稱:296-25851-6
LTC2495IUHF#TRPBF 功能描述:IC ADC 16BIT W/PGA 38-QFN 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(biāo)準(zhǔn)包裝:1,000 系列:- 位數(shù):16 采樣率（每秒）:45k 數(shù)據(jù)接口:串行 轉(zhuǎn)換器數(shù)目:2 功率耗散（最大）:315mW 電壓電源:模擬和數(shù)字 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:28-SOIC W 包裝:帶卷 (TR) 輸入數(shù)目和類型:2 個(gè)單端，單極
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