- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄39420 > LTC2494IUHF (LINEAR TECHNOLOGY CORP) 16-CH 16-BIT DELTA-SIGMA ADC, SERIAL ACCESS, PQCC38 PDF資料下載
參數(shù)資料
| 型號(hào)： | LTC2494IUHF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | ADC |
| 英文描述： | 16-CH 16-BIT DELTA-SIGMA ADC, SERIAL ACCESS, PQCC38 |
| 封裝： | 5 X 7 MM, PLASTIC, MO-220WKHD, QFN-38 |
| 文件頁數(shù)： | 20/36頁 |
| 文件大?。?/td> | 675K |
| 代理商： | LTC2494IUHF |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁當(dāng)前第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁第33頁第34頁第35頁第36頁
LTC2494
2494fa
applicaTions inFormaTion
PRESERVING THE CONVERTER ACCURACY
The LTC2494 is designed to reduce as much as possible
sensitivity to device decoupling, PCB layout, anti-aliasing
circuits, line frequency perturbations, and temperature
sensitivity. In order to achieve maximum performance a
few simple precautions should be observed.
Digital Signal Levels
The LTC2494’s digital interface is easy to use. Its digital
inputs SDI, FO,CS,andSCk(inexternalserialclockmode)
accept standard CMOS logic levels. Internal hysteresis
circuits can tolerate edge transition times as slow as
100s.
The digital input signal range is 0.5V to VCC – 0.5V. During
transitions, the CMOS input circuits draw dynamic cur-
rent. For optimal performance, application of signals to
the serial data interface should be reserved for the sleep
and data output periods.
During the conversion period, overshoot and undershoot
of fast digital signals applied to both the serial digital in-
terface and the external oscillator pin (FO) may degrade
the converter performance. Undershoot and overshoot
occur due to impedance mismatch of the circuit board
trace at the converter pin when the transition time of an
external control signal is less than twice the propagation
delay from the driver to the input pin. For reference, on a
regularFR-4board,thepropagationdelayisapproximately
183ps/inch. In order to prevent overshoot, a driver with
a 1ns transition time must be connected to the converter
through a trace shorter than 2.5 inches. This becomes
difficult when shared control lines are used and multiple
reflections occur.
Parallel termination near the input pin of the LTC2494 will
eliminate this problem, but will increase the driver power
dissipation. A series resistor from 27
Ω to 54Ω (depend-
ing on the trace impedance and connection) placed near
the driver will also eliminate over/under shoot without
additional driver power dissipation.
For many applications, the serial interface pins (SCk, SDI,
CS, FO) remain static during the conversion cycle and
no degradation occurs. On the other hand, if an external
oscillator is used (FO driven externally) it is active during
the conversion cycle. Moreover, the digital filter rejection
is minimal at the clock rate applied to FO. Care must be
taken to ensure external inputs and reference lines do not
cross this signal or run near it. These issues are avoided
when using the internal oscillator.
Driving the Input and Reference
TheinputandreferencepinsoftheLTC2494areconnected
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 simplified equivalent circuit is
shown in Figure 12.
When using the LTC2494’s internal oscillator, the input
capacitor array is switched at 123kHz. The effect of the
charge transfer depends on the circuitry driving the in-
put/reference pins. If the total external RC time constant
is less then 580ns the errors introduced by the sampling
process are negligible since complete settling occurs.
Typically,thereferenceinputsaredrivenfromalowimped-
ance source. In this case, complete settling occurs even
with large external bypass capacitors. The inputs (CH0 to
CH15, COM), on the other hand, are typically driven from
larger source resistances. Source resistances up to 10k
mayinterfacedirectlytotheLTC2494andsettlecompletely;
however, the addition of external capacitors at the input
terminals in order to filter unwanted noise (anti-aliasing)
results in incomplete settling.
TheLTC2494offerstwomethodsofremovingtheseerrors.
The first is automatic differential input current cancella-
tion (Easy Drive) and the second is the insertion of buffer
between the MUXOUT and ADCIN pins, thus isolating the
input switching from the source resistance.
Automatic Differential Input Current Cancellation
In applications where the sensor output impedance is
low (up to 10k
Ω with no external bypass capacitor or up
to 500
Ω with 0.001F bypass), complete settling of the
input occurs. In this case, no errors are introduced and
direct digitization is possible.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC2494CUHF#TR | 16-CH 16-BIT DELTA-SIGMA ADC, SERIAL ACCESS, PQCC38 |
| LTC2495IUHF#TR | 16-CH 16-BIT DELTA-SIGMA ADC, SERIAL ACCESS, PQCC38 |
| LTC2495CUHF#TR | 16-CH 16-BIT DELTA-SIGMA ADC, SERIAL ACCESS, PQCC38 |
| LTC2615IGN#TR | SERIAL INPUT LOADING, 9 us SETTLING TIME, 14-BIT DAC, PDSO16 |
| LTC2620CUFD#PBF | SERIAL INPUT LOADING, 7 us SETTLING TIME, 12-BIT DAC, PQCC20 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC2494IUHF#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)品目錄頁面:892 (CN2011-ZH PDF) 其它名稱:296-25851-6 |
| LTC2494IUHF#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 |
| 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 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。