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參數(shù)資料
| 型號： | ADS7812UB |
| 英文描述： | Low-Power, Serial 12-Bit Sampling ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 低功耗，串行12位采樣模擬到數(shù)字轉(zhuǎn)換器 |
| 文件頁數(shù)： | 12/17頁 |
| 文件大小： | 381K |
| 代理商： | ADS7812UB |
12
ADS7812
External DATACLK Active After the Conversion
and During the Next Conversion
Figure 8 shows a method that is a hybrid of the two previous
approaches. This method works very well for microcontrollers
that do serial transfers 8 bits at a time and for slower
microcontrollers. For example, if the fastest serial clock that
the microcontroller can produce is 1
μ
s, and two 8-bit trans-
fers must be used to obtain the serial data, the approach
shown in Figure 6 would result in a diminished throughput
(26kHz maximum conversion rate). The method described
in Figure 7 could not be used because time t
25
would be
violated. The approach in Figure 8 results in an improved
throughput rate (33kHz maximum with a 1
μ
s clock) and
DATACLK is LOW during t
25
.
COMPATIBILITY WITH THE ADS7813
The only difference between the ADS7812 and the ADS7813
is in the internal control logic and the digital interface. Since
the ADS7813 is a 16-bit converter, the internal shift register
is 16 bits wide. In addition, only 16-bit decisions are made
during the conversion. Thus, the ADS7813’s conversion
time is approximately 133% of the ADS7812’s.
The timing presented in this data sheet will allow as much
compatibility as possible with the ADS7813. The main
concern will be the different number of serial clocks. If a
design must be compatible with both the ADS7812 and
ADS7813, it is recommended to consider the ADS7813
first. If the design works with the ADS7813, it will certainly
work with the ADS7812. This is also true in regards to
layout (see the Layout section of this data sheet).
CHIP SELECT (CS)
The CS input allows the digital outputs of the ADS7812 to
be disabled and gates the external DATACLK signal when
EXT/INT is HIGH. See Figure 9 for the enable and disable
time associated with CS and Figure 3 for a block diagram of
the ADS7812’s logic. The digital outputs can be disabled at
any time.
Note that a conversion is initiated on the falling edge of CONV
even if CS is HIGH. If the EXT/INT input is LOW (internal
DATACLK) and CS is HIGH during the entire conversion, the
previous conversion result will be lost (the serial transmission
occurs but DATA and DATACLK are disabled).
TABLE IV. Complete List of Ideal Input Ranges.
ANALOG
INPUT
RANGE (V)
CONNECT
R1
IN
TO
CONNECT
R2
IN
TO
CONNECT
R3
IN
TO
INPUT
IMPEDANCE
(k
)
COMMENT
0.3125 to 2.8125
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
BUF
V
IN
V
IN
V
IN
BUF
V
IN
BUF
> 10,000
Guaranteed offset and gain
–0.417 to 2.916
26.7
V
IN
cannot go below GND – 0.3V
Offset and gain not guaranteed
0.417 to 3.750
GND
26.7
±
3.333
–15 to 5
V
IN
BUF
21.3
Guaranteed offset and gain
BUF
45.7
Offset and gain not guaranteed
±
10
BUF
GND
45.7
Guaranteed offset and gain
0.833 to 7.5
GND
V
IN
BUF
21.3
Offset and gain not guaranteed
–2.5 to 17.5
GND
45.7
Exceeds absolute maximum V
IN
Exceeds absolute maximum V
IN
Offset and gain not guaranteed
2.5 to 22.5
GND
GND
45.7
0 to 2.857
V
IN
V
IN
V
IN
BUF
V
IN
BUF
45.7
–1 to 3
BUF
21.3
V
IN
cannot go below GND – 0.3V
Guaranteed offset and gain
0 to 4
BUF
GND
21.3
–6.25 to 3.75
BUF
V
IN
V
IN
V
IN
BUF
26.7
Offset and gain not guaranteed
0 to 10
BUF
GND
26.7
Guaranteed offset and gain
0.357 to 3.214
GND
V
IN
V
IN
V
IN
BUF
45.7
Offset and gain not guaranteed
–0.5 to 3.5
GND
21.3
V
IN
cannot go below GND – 0.3V
Guaranteed offset and gain
0.5 to 4.5
GND
GND
21.3
±
5
GND
V
IN
V
IN
26.7
Guaranteed offset and gain
1.25 to 11.25
GND
GND
26.7
Offset and gain not guaranteed
ANALOG INPUT
The ADS7812 offers a number of input ranges. This is
accomplished by connecting the three input resistors to
either the analog input (V
IN
), to ground (GND), or to the
2.5V reference buffer output (BUF). Table I shows the
input ranges that are typically used in data acquisition
applications. These ranges are all guaranteed to meet the
specifications given in the Specifications table. Table IV
contains a complete list of ideal input ranges, associated
input connections, and comments regarding the range.
Active
HI-Z
HI-Z
BUSY, DATA,
DATACLK
(1)
CS
t
27
t
26
NOTE: (1) DATACLK is an output only when EXT/INT is LOW.
FIGURE 9. Enable and Disable Timing for Digital Outputs.
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PDF描述 |
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| ADS7813 | Low-Power, Serial 16-Bit Sampling ANALOG-TO-DIGITAL CONVERTER |
| ADS7813UB | WIRE, PTFE, A, VIOLET, 7/0.12MM, 100M; Area, conductor CSA:0.079mm2; Conductor make-up:7/0.12mm; Voltage rating, AC:300V; Current rating:3A; Colour, primary insulation:Violet; Material, primary insulation:PTFE; Diameter, RoHS Compliant: Yes |
| ADS7813U | Low-Power, Serial 16-Bit Sampling ANALOG-TO-DIGITAL CONVERTER |
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| ADS7813PB | Low-Power, Serial 16-Bit Sampling ANALOG-TO-DIGITAL CONVERTER |
相關代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS7812UB/1K | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Power Serial 12-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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS7812UB/1KE4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Power Serial 12-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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS7812UB/1KG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Pwr Serial 12B Sampling 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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS7812UBE4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Power Serial 12-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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS7812UBG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Low-Pwr Serial 12B Sampling 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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32 |
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