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參數(shù)資料
| 型號： | ADC081S021 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Single Channel, 500 kSPS, 8-Bit A/D Converter |
| 中文描述： | 單通道，500 kSPS的，8位A / D轉(zhuǎn)換器 |
| 文件頁數(shù)： | 12/13頁 |
| 文件大?。?/td> | 621K |
| 代理商： | ADC081S021 |
Applications Information
(Continued)
To exit shutdown mode, bring CS back low. Upon bringing
CS low, the ADC081S051 will begin powering up (power-up
time is specified in the Timing Specifications table). This
microsecond of power-up delay results in the first conversion
result being unusable. The second conversion performed
after power-up, however, is valid, as shown in Figure 9.
If CS is brought back high before the 10th falling edge of
SCLK, the device will return to shutdown mode. This is done
to avoid accidentally entering normal mode as a result of
noise on the CS line. To exit shutdown mode and remain in
normal mode, CS must be kept low until after the 10th falling
edge of SCLK. The ADC081S051 will be fully powered-up
after 16 SCLK cycles.
8.0 POWER MANAGEMENT
The ADC081S051 takes time to power-up, either after first
applying V
A
, or after returning to normal mode from shut-
down mode. This corresponds to one "dummy" conversion
for any SCLK frequency within the specifications in this
document.
After
this
first
ADC081S051 will perform conversions properly. Note that
the t
time must still be included between the first
dummy conversion and the second valid conversion.
When the V
supply is first applied, the ADC081S051 may
power up in either of the two modes: normal or shutdown.As
such, one dummy conversion should be performed after
start-up, exactly as described in the previous paragraph. The
part may then be placed into either normal mode or the
shutdown mode, as described in Sections 7.1 and 7.2.
When the ADC081S051 is operated continuously in normal
mode, the maximum throughput is f
/20. Throughput
may be traded for power consumption by running f
at its
maximum 10.0 MHz and performing fewer conversions per
unit time, putting the ADC081S051 into shutdown mode
dummy
conversion,
the
between conversions. A plot of typical power consumption
versus throughput is shown in the Typical Performance
Curves section. To calculate the power consumption for a
given throughput, multiply the fraction of time spent in the
normal mode by the normal mode power consumption and
add the fraction of time spent in shutdown mode multiplied
by the shutdown mode power consumption. Generally, the
user will put the part into normal mode and then put the part
back into shutdown mode. Note that the curve of power
consumption vs. throughput is nearly linear. This is because
the power consumption in the shutdown mode is so small
that it can be ignored for all practical purposes.
9.0 POWER SUPPLY NOISE CONSIDERATIONS
The charging of any output load capacitance requires cur-
rent from the power supply, V
A
. The current pulses required
from the supply to charge the output capacitance will cause
voltage variations on the supply. If these variations are large
enough, they could degrade SNR and SINAD performance
of the ADC. Furthermore, discharging the output capaci-
tance when the digital output goes from a logic high to a logic
low will dump current into the die substrate, which is resis-
tive. Load discharge currents will cause "ground bounce"
noise in the substrate that will degrade noise performance if
that current is large enough. The larger the output capaci-
tance, the more current flows through the die substrate and
the greater is the noise coupled into the analog channel,
degrading noise performance.
To keep noise out of the power supply, keep the output load
capacitance as small as practical. If the load capacitance is
greater than 25 pF, use a 100
series resistor at the ADC
output, located as close to the ADC output pin as practical.
This will limit the charge and discharge current of the output
capacitance and improve noise performance.
20145517
FIGURE 9. Entering Normal Mode
A
www.national.com
12
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參數(shù)描述 |
|---|---|
| ADC081S021CIMF | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 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 |
| ADC081S021CIMF/NOPB | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 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 |
| ADC081S021CIMFX | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 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 |
| ADC081S021CIMFX/NOPB | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 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 |
| ADC081S021CISD | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 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 |
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