- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄10084 > AD7634BCPZRL (Analog Devices Inc)IC ADC 18BIT DIFF BIPO 48-LFCSP PDF資料下載
參數(shù)資料
| 型號： | AD7634BCPZRL |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 14/32頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC ADC 18BIT DIFF BIPO 48-LFCSP |
| 標(biāo)準(zhǔn)包裝： | 2,500 |
| 系列： | PulSAR® |
| 位數(shù)： | 18 |
| 采樣率（每秒）： | 670k |
| 數(shù)據(jù)接口： | 串行，并聯(lián) |
| 轉(zhuǎn)換器數(shù)目： | 1 |
| 功率耗散（最大）： | 225mW |
| 電壓電源： | 模擬和數(shù)字 |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 48-VFQFN 裸露焊盤，CSP |
| 供應(yīng)商設(shè)備封裝： | 48-LFCSP-VQ（7x7） |
| 包裝： | 帶卷 (TR) |
| 輸入數(shù)目和類型： | 1 個(gè)差分，單極；1 個(gè)差分，雙極 |
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頁當(dāng)前第14頁第15頁第16頁第17頁第18頁第19頁第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
Data Sheet
AD7634
Rev. B | Page 21 of 32
DRIVER AMPLIFIER CHOICE
Although the AD7634 is easy to drive, the driver amplifier must
meet the following requirements:
For multichannel, multiplexed applications, the driver ampli-
fier and the AD7634 analog input circuit must be able to
settle for a full-scale step of the capacitor array at a 18-bit
level (0.0004%). For the amplifier, settling at 0.1% to 0.01%
is more commonly specified. This differs significantly from
the settling time at a 18-bit level and should be verified
prior to driver selection. The AD8021 op amp combines ultra-
low noise and high gain bandwidth and meets this settling
time requirement even when used with gains of up to 13.
The noise generated by the driver amplifier needs to be
kept as low as possible to preserve the SNR and transition
noise performance of the AD7634. The noise coming from
the driver is filtered by the external 1-pole low-pass filter,
as shown in Figure 27. The SNR degradation due to the
amplifier is
2
3
2
3
2
)
(
2
)
(
2
log
20
N
dB
N
dB
NADC
LOSS
Ne
f
Ne
f
V
SNR
where:
VNADC is the noise of the ADC, which is:
20
10
2
SNR
INp-p
NADC
V
f–3dB is the cutoff frequency of the input filter (3.9 MHz).
N is the noise factor of the amplifier (+1 in buffer
configuration).
eN+ and eN are the equivalent input voltage noise densities
of the op amps connected to IN+ and IN, in nV/√Hz.
This approximation can be utilized when the resistances
used around the amplifiers are small. If larger resistances are
used, their noise contributions should also be root-sum
squared.
The driver needs to have a THD performance suitable to
that of the AD7634. Figure 15 shows the THD vs. frequency
that the driver should exceed.
The AD8021 meets these requirements and is appropriate for
almost all applications. The AD8021 needs a 10 pF external
compensation capacitor that should have good linearity as an
NPO ceramic or mica type. Moreover, the use of a noninverting
+1 gain arrangement is recommended and helps to obtain the
best signal-to-noise ratio.
The AD8022 can also be used when a dual version is needed
and a gain of 1 is present. The AD829 is an alternative in appli-
cations where high frequency (above 100 kHz) performance is not
required. In applications with a gain of 1, an 82 pF compensation
capacitor is required. The AD8610 is an option when low bias
current is needed in low frequency applications.
Because the AD7634 uses a large geometry, high voltage input
switch, the best linearity performance is obtained when using
the amplifier at its maximum full power bandwidth. Gaining
the amplifier to make use of the more dynamic range of the
ADC results in increased linearity errors. For applications
requiring more resolution, the use of an additional amplifier
with gain should precede a unity follower driving the AD7634.
See Table 9 for a list of recommended op amps.
Table 9. Recommended Driver Amplifiers
Amplifier
Typical Application
±15 V supplies, very low noise, low frequency
±12 V supplies, very low noise, high frequency
±12 V supplies, very low noise, high
frequency, dual
±12 V supplies, low noise, high frequency,
single-ended-to-differential driver
±13 V supplies, low bias current, low
frequency, single/dual
Single-to-Differential Driver
For single-ended sources, a single-to-differential driver, such
as the ADA4922-1, can be used because the AD7634 needs to
be driven differentially. The 1-pole filter using R = 15 Ω and
C = 2.7 nF provides a corner frequency of 3.9 MHz.
06
406-
052
ANALOG
INPUT
IN+
IN–
AD7634
REF
10F
15
100nF
2.7nF
U2
R1
R2
ADA4922-1
OUT+
VCC
VEE
OUT–
IN
REF
RF
RG
Figure 31. Single-to-Differential Driver Using the ADA4922-1
For unipolar 5 V and 10 V input ranges, the internal (or
external) reference source can be used to level shift U2 for
the correct input span. If using an external reference, the
values for R1/R2 can be lowered to reduce resistive Johnson
noise (1.29E 10 × √R). For the bipolar ±5 V and ±10 V input
ranges, the reference connection is not required because the
common-mode voltage is 0 V. See Table 10 for R1/R2 for the
different input ranges.
Table 10. R1/R2 Configuration
Input Range
R1
R2
Common-Mode Voltage
5 V
2.5 kΩ
2.5 V
10 V
2.5 kΩ
Open
5 V
±5 V, ±10 V
100 Ω
0 V
This circuit can also be made discretely, and thus more flexible,
using any of the recommended low noise amplifiers in Table 9.
Again, to preserve the SNR of the converter, the resistors, RF
and RG, should be kept low.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| D38999/26WD15PC | CONN PLUG 15POS STRAIGHT W/PINS |
| IDT72V235L15TF8 | IC FIFO SYNC 2048X18 15NS 64QFP |
| AD774BJNZ | IC ADC 12BIT W/BUFF REF 28DIP |
| VE-2N1-IW-F3 | CONVERTER MOD DC/DC 12V 100W |
| IDT72245LB25TF8 | IC FIFO 1024X18 SYNC 25NS 64QFP |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD7634BSTZ | 功能描述:IC ADC 18BIT DIFF BIPO 48-LQFP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:PulSAR® 標(biāo)準(zhǔn)包裝:1 系列:- 位數(shù):14 采樣率（每秒）:83k 數(shù)據(jù)接口:串行，并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應(yīng)商設(shè)備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個(gè)單端，雙極 |
| AD7634BSTZRL | 功能描述:IC ADC 18BIT DIFF BIPO 48-LQFP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:PulSAR® 標(biāo)準(zhǔn)包裝:1 系列:- 位數(shù):14 采樣率（每秒）:83k 數(shù)據(jù)接口:串行，并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應(yīng)商設(shè)備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個(gè)單端，雙極 |
| AD7641 | 制造商:AD 制造商全稱:Analog Devices 功能描述:16-Bit, 750 kSPS, Unipolar/Bipolar Programmable Input PulSAR ADC |
| AD7641ACP | 制造商:Analog Devices 功能描述:ADC SGL SAR 2MSPS 18BIT PARALLEL/SERL 48LFCSP - Trays |
| AD7641ACPRL | 制造商:Analog Devices 功能描述:ADC SGL SAR 2MSPS 18BIT PARALLEL/SERL 48LFCSP - Tape and Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。