- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄364640 > ADS7813PB Low-Power, Serial 16-Bit Sampling ANALOG-TO-DIGITAL CONVERTER PDF資料下載
參數(shù)資料
| 型號： | ADS7813PB |
| 英文描述： | Low-Power, Serial 16-Bit Sampling ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 低功耗，串行16位采樣模擬到數(shù)字轉(zhuǎn)換器 |
| 文件頁數(shù)： | 16/17頁 |
| 文件大?。?/td> | 376K |
| 代理商： | ADS7813PB |
16
ADS7813
Keep in mind that the time period when the comparator is
most sensitive to noise is fairly small. Also, the peak portion
of the noise “event” produced by a digital transition is fairly
brief as most digital signals transition in a few nanoseconds.
The subsequent noise may last for a period of time longer
than this and may induce further effects which require a
longer settling time. However, in general, the event is over
within a few tens of nanoseconds.
For the ADS7813, error correction is done when the tenth bit
is decided. During this bit decision, it is possible to correct
limited errors that may have occurred during previous bit
decisions. However, after the tenth bit, no such correction is
possible. Note that for the timing diagrams shown in Figures
2, 5, 6, 7, and 8, all external digital signals should remain
static from 8
μ
s after the start of a conversion until BUSY
rises. The tenth bit is decided approximately 10
μ
s to 11
μ
s
into the conversion.
APPLICATIONS INFORMATION
TRANSITION NOISE
If a low-noise DC input is applied to the ADS7813 and 1,000
conversions are performed, the digital output of the con-
verter will vary slightly in output codes. This is true for all
16-bit SAR converters. The transition noise specification
found in the Specifications section is a statistical figure
which represents the one sigma limit of these output codes.
Using a histogram to plot the number of occurances of each
output code, the distribution should appear bell-shaped with
the peak of the curve representing the nominal output code
for the given input voltage. The
±
1
σ
,
±
2
σ
, and
±
3
σ
limits
around this nominal code should contain 68.3%, 95.5%, and
99.7%, respectively, of the conversion results. As a rough
approximation, multiplying transition noise by 6 (
±
3
σ
) will
yield the number of unique output codes which should be
present in 1,000 conversions.
The ADS7813 has a transition noise figure of 0.6LSB,
yielding approximately 4 different output codes for 1,000
conversions. However, since
±
3
σ
is only 99.7%, up to three
FIGURE 14. Histogram of 5,000 Conversions with Input
Grounded.
23
FFFEh
821
FFFFh
3291
0000h
832
0001h
33
0002h
0
0
0003h
FFFDh
conversions have some chance of being outside this range.
In addition, the differential linearity error of each code and
the quantization performed by the converter result in histo-
grams which can deviate from the ideal. Figure 14 shows a
histogram of 5,000 conversions from the ADS7813.
AVERAGING
The noise of the converter can be reduced by averaging
conversion results. The noise will be reduced by a factor of
1/
√
n, where ‘n’ is the number of averages. For example,
averaging four conversions will reduce transition noise by
half, to 0.3LSBs. Averaging should only be used for low-
frequency signals.
For higher frequency signals, a digital filter can be used to
reduce noise. This works in a similar manner to averaging:
for every reduction in the signal bandwidth by two, the
signal-to-noise ratio will improve by 3dB.
QSPI INTERFACING
Figure 15 shows a simple interface between the ADS7813
and any queued serial peripheral interface (QSPI) equipped
microcontroller (available on several Motorola devices).
This interface assumes that the convert pulse does not
originate from the microcontroller and that the ADS7813 is
the only serial peripheral.
CONV
BUSY
DATA
DATACLK
CS
EXT/INT
ADS7813
PCS0/SS
MOSI
SCK
QSPI
CPOL = 0 (Inactive State is LOW)
CPHA = 1 (Data valid on falling edge)
QSPI port is in slave mode.
Convert Pulse
FIGURE 15. QSPI Interface to the ADS7813.
Before enabling the QSPI interface, the microcontroller
must be configured to monitor the slave select (SS) line.
When a LOW to HIGH transition occurs (indicating the end
of a conversion), the port can be enabled. If this is not done,
the microcontroller and A/D converter may not be properly
synchronized. (The slave select line simply enables commu-
nication—it does not indicate the start or end of a serial
transfer.)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADS7821UB | 16-Bit 10ms Sampling CMOS ANALOG-to-DIGITAL CONVERTER |
| ADS7821P | CMOS Dual 4-Input NOR Gate 14-SO -55 to 125 |
| ADS7821U | 16-Bit 10ms Sampling CMOS ANALOG-to-DIGITAL CONVERTER |
| ADS7822 | CMOS Dual 4-Input NOR Gate 14-TSSOP -55 to 125 |
| ADS7822B | 12-Bit High Speed 2.7V microPower Sampling ANALOG-TO-DIGITAL CONVERTER |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS7813PB | 制造商:Texas Instruments 功能描述:A/D CONVERTER (A-D) IC |
| ADS7813PBG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Power Serial 16-Bit Sampling 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 |
| ADS7813PG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Power Serial 16-Bit Sampling 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 |
| ADS7813U | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Power Serial 16-Bit Sampling 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 |
| ADS7813U/1K | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Power Serial 16-Bit Sampling 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 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。