- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄10084 > AD7634BSTZRL (Analog Devices Inc)IC ADC 18BIT DIFF BIPO 48-LQFP PDF資料下載
參數(shù)資料
| 型號： | AD7634BSTZRL |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 15/32頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC ADC 18BIT DIFF BIPO 48-LQFP |
| 標(biāo)準(zhǔn)包裝： | 2,000 |
| 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-LQFP |
| 供應(yīng)商設(shè)備封裝： | 48-LQFP（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頁第14頁當(dāng)前第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
AD7634
Data Sheet
Rev. B | Page 22 of 32
VOLTAGE REFERENCE INPUT/OUTPUT
The AD7634 allows the choice of either a very low temperature
drift internal voltage reference, an external reference, or an
external buffered reference.
The internal reference of the AD7634 provides excellent perform-
ance and can be used in almost all applications. However, the
linearity performance is guaranteed only with an external reference.
Internal Reference (REF = 5 V) (PDREF = Low,
PDBUF = Low)
To use the internal reference, the PDREF and PDBUF inputs
must be low. This enables the on-chip, band gap reference, buffer,
and TEMP sensor, resulting in a 5.00 V reference on the REF pin.
The internal reference is temperature-compensated to 5.000 V
± 35 mV. The reference is trimmed to provide a typical drift of
3 ppm/°C. This typical drift characteristic is shown in Figure 19.
External 2.5 V Reference and Internal Buffer (REF = 5 V)
(PDREF = High, PDBUF = Low)
To use an external reference with the internal buffer, PDREF
should be high and PDBUF should be low. This powers down
the internal reference and allows the 2.5 V reference to be applied
to REFBUFIN producing 5 V on the REF pin. The internal ref-
erence buffer is useful in multiconverter applications because
a buffer is typically required in these applications to avoid
reference coupling amongst the different converters.
External 5 V Reference (PDREF = High, PDBUF = High)
To use an external reference directly on the REF pin, PDREF
and PDBUF should both be high. PDREF and PDBUF power
down the internal reference and the internal reference buffer,
respectively. For improved drift performance, an external refer-
ence, such as the ADR445 or ADR435, is recommended.
Reference Decoupling
Whether using an internal or external reference, the AD7634
voltage reference input (REF) has a dynamic input impedance;
therefore, it should be driven by a low impedance source with
efficient decoupling between the REF and REFGND inputs. This
decoupling depends on the choice of the voltage reference but
usually consists of a low ESR capacitor connected to REF and
REFGND with minimum parasitic inductance. A 22 μF (X5R,
1206 size) ceramic chip capacitor (or 47 μF low ESR tantalum
capacitor) is appropriate when using either the internal refer-
ence or the ADR445/ADR435 external reference.
The placement of the reference decoupling is also important to
the performance of the AD7634. The decoupling capacitor should
be mounted on the same side as the ADC right at the REF pin
with a thick PCB trace. The REFGND should also connect to
the reference decoupling capacitor with the shortest distance
and to the analog ground plane with several vias.
For applications that use multiple AD7634 or other PulSAR
devices, it is more effective to use the internal reference buffer
to buffer the external 2.5 V reference voltage.
The voltage reference temperature coefficient (TC) directly
impacts full scale; therefore, in applications where full-scale
accuracy matters, care must be taken with the TC. For instance,
a ±4 ppm/°C TC of the reference changes full scale by ±1 LSB/°C.
Temperature Sensor
The TEMP pin measures the temperature of the AD7634. To
improve the calibration accuracy over the temperature range, the
output of the TEMP pin is applied to one of the inputs of the
analog switch (such as ADG779), and the ADC itself is used to
measure its own temperature. This configuration is shown
in Figure 32.
ADG779
CC
ANALOG INPUT
AD7634
IN+
TEMPERATURE
SENSOR
TEMP
06
40
6-
03
0
Figure 32. Use of the Temperature Sensor
POWER SUPPLIES
The AD7634 uses five sets of power supply pins:
AVDD: analog 5 V core supply
VCC: analog high voltage positive supply
VEE: high voltage negative supply
DVDD: digital 5 V core supply
OVDD: digital input/output interface supply
Core Supplies
The AVDD and DVDD supply the AD7634 analog and digital
cores, respectively. Sufficient decoupling of these supplies is
required consisting of at least a 10 μF capacitor and a 100 nF
capacitor on each supply. The 100 nF capacitors should be
placed as close as possible to the AD7634. To reduce the number
of supplies needed, the DVDD can be supplied through a simple
RC filter from the analog supply, as shown in Figure 27.
High Voltage Supplies
The high voltage bipolar supplies, VCC and VEE, are required
and must be at least 2 V larger than the maximum input voltage.
For example, if using the ±10 V range, the supplies should be
±12 V minimum. This allows for 40 V p-p fully differential
input (±10 V on each input IN+ and IN). Sufficient decoup-
ling of these supplies is also required consisting of at least a
10 μF capacitor and a 100 nF capacitor on each supply. For
unipolar operation, the VEE supply can be grounded with
some slight THD performance degradation.
Digital Output Supply
The OVDD supplies the digital outputs and allows direct interface
with any logic working between 2.3 V and 5.25 V. OVDD should
be set to the same level as the system interface. Sufficient decoup-
ling is required consisting of at least a 10 μF capacitor and a 100 nF
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| VE-2N1-IW-F4 | CONVERTER MOD DC/DC 12V 100W |
| IDT72V245L20TF8 | IC FIFO SYNC 4096X18 20NS 64QFP |
| AD7634BCPZRL | IC ADC 18BIT DIFF BIPO 48-LFCSP |
| D38999/26WD15PC | CONN PLUG 15POS STRAIGHT W/PINS |
| IDT72V235L15TF8 | IC FIFO SYNC 2048X18 15NS 64QFP |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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 |
| AD7641AST | 制造商:Analog Devices 功能描述:ADC SGL SAR 2MSPS 18BIT PARALLEL/SERL 48LQFP - Bulk |
| AD7641ASTRL | 制造商:Analog Devices 功能描述:ADC SGL SAR 2MSPS 18BIT PARALLEL/SERL 48LQFP - Tape and Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。