參數(shù)資料
型號(hào)： ADS5270IPFP
英文描述： 8-Channel, 12-Bit, 40MSPS ADC with Serial LVDS Interface
中文描述： 8通道，12位，40MSPS的ADC的串行LVDS接口
文件頁(yè)數(shù)： 14/18頁(yè)
文件大小： 439K
代理商： ADS5270IPFP
"#$%&
SBAS293D JANUARY 2004 REVISED MAY 2004
www.ti.com
14
The sampling circuit consists of a low-pass RC filter at the
input to filter out noise components that might be getting
differentially coupled on the input pins. The inputs are
sampled on two 4pF capacitors. The sampling on the
capacitors is done with respect to an internally generated
common-mode voltage (INCM). The switches connecting
the sampling capacitors to the INCM are opened out first
(before the switches connecting them to the analog
inputs). This ensures that the charge injection arising out
of the switches opening is independent of the input signal
amplitude to a first-order of approximation. SP refers to a
sampling clock whose falling edge comes an instant
before the SAMPLE clock. The falling edge of SP
determines the sampling instant.
15
IN
1.5pF
SP
SP
SP
(defines sampling instant)
INCM
(internally generated voltage)
INCM
4pF
Sample
15
IN+
1.5pF
1.7pF
4pF
Sample
Figure 2. Input Circuitry
INPUT OVER-VOLTAGE RECOVERY
The differential full-scale input peak-to-peak supported by
the ADS5270 is 2V. For a nominal value of V
CM
(1.5V), IN
P
and IN
N
can swing from 1V to 2V. The ADS5270 is
specially designed to handle an over-voltage differential
peak-to-peak voltage of 4V (2.5V and 0.5V swings on IN
P
and IN
N
). If the input common-mode is not considerably off
from V
CM
during overload (less than 300mV), recovery
from an over-voltage input condition is expected to be
within 4 clock cycles. All of the amplifiers in the SHA and
ADC are specially designed for excellent recovery from an
overload signal.
REFERENCE CIRCUIT DESIGN
The digital beam-forming algorithm relies heavily on gain
matching across all receiver channels. A typical system
would have about 12 octal ADCs on the board. In such a
case, it is critical to ensure that the gain is matched,
essentially requiring the reference voltages seen by all the
ADCs to be the same. Matching references within the eight
channels of a chip is done by using a single internal
reference voltage buffer. Trimming the reference voltages
on each chip during production ensures the reference
voltages are well matched across different chips.
All bias currents required for the internal operation of the
device are set using an external resistor to ground at pin
ISET. Using a 56k
resistor on ISET generates an internal
reference current of 20
μ
A. This current is mirrored
internally to generate the bias current for the internal
blocks. Using a larger external resistor at ISET reduces the
reference bias current and thereby scales down the device
operating power. However, it is recommended that the
external resistor be within 10% of the specified value of
56k so that the internal bias margins for the various blocks
are proper.
Buffering the internal bandgap voltage also generates a
voltage called V
CM
, which is set to the midlevel of REF
T
and REF
B
, and is accessible on a pin. The internal buffer
driving V
CM
has a drive of
±
2mA. It is meant as a reference
voltage to derive the input common-mode in case the input
is directly coupled.
When using the internal reference mode, a resistor greater
than 2
should be added between the reference pins
(REF
T
and REF
B
) and the decoupling capacitor, as shown
in Figure 3.
REF
T
REF
B
0.1
μ
F
2.2
μ
F
> 2
> 2
2.2
μ
F
0.1
μ
F
ADS5270
Figure 3. Internal Refernce Mode
The device also supports the use of external reference
voltages. This mode involves forcing REF
T
and REF
B
externally. In this mode, the internal reference buffer is
tri-stated. Since the switching current for the eight ADCs
come from the externally forced references, it is possible
for the performance to be slightly less than when the
internal references are used. It should be noted that in this
mode, V
CM
and ISET continue to be generated from the
internal bandgap voltage, as in the internal reference
mode. It is therefore important to ensure that the
common-mode voltage of the externally forced reference
voltages matches to within 50mV of V
CM
.
CLOCKING
The eight channels on the chip run off a single ADCLK
input. To ensure that the aperture delay and jitter are same
for all the channels, a clock tree network is used to
generate individual sampling clocks to each channel. The
相關(guān)PDF資料
PDF描述
ADS5270IPFPT 8-Channel, 12-Bit, 40MSPS ADC with Serial LVDS Interface
ADS5271 8-Channel, 12-Bit, 50MSPS ADC with Serial LVDS Interface
ADS5271IPFP 8-Channel, 12-Bit, 50MSPS ADC with Serial LVDS Interface
ADS5271IPFPT 8-Channel, 12-Bit, 50MSPS ADC with Serial LVDS Interface
ADS5421 PLUG, PCB, VERTICAL, 20WAY; Connector type:Wire-to-Board; Gender:Plug; Ways, No. of:20; Pitch, lead:1.27mm; Termination method:Solder; Material, contact:Phosphor Bronze; Plating, contact:Gold over Nickel; Rows, No. of:2; Pitch:0.05"; RoHS Compliant: Yes
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ADS5270IPFPG4 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 8-Ch Anlg-to-Dig Converter RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
ADS5270IPFPT 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 8-Ch Anlg-to-Dig Converter RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
ADS5270IPFPTG4 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 8-Ch Anlg-to-Dig Converter RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
ADS5271 制造商:BB 制造商全稱:BB 功能描述:8-Channel, 12-Bit, 50MSPS ADC with Serial LVDS Interface
ADS5271EVM 功能描述:數(shù)據(jù)轉(zhuǎn)換 IC 開(kāi)發(fā)工具 ADS5271 Eval Mod RoHS:否 制造商:Texas Instruments 產(chǎn)品:Demonstration Kits 類型:ADC 工具用于評(píng)估:ADS130E08 接口類型:SPI 工作電源電壓:- 6 V to + 6 V
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*