- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄10407 > ADS7812UB/1KE4 (Texas Instruments)IC 12BIT 35MW SER OUT ADC 16SOIC PDF資料下載
參數(shù)資料
| 型號(hào)： | ADS7812UB/1KE4 |
| 廠商： | Texas Instruments |
| 文件頁數(shù)： | 5/24頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC 12BIT 35MW SER OUT ADC 16SOIC |
| 產(chǎn)品培訓(xùn)模塊： | Data Converter Basics |
| 標(biāo)準(zhǔn)包裝： | 1,000 |
| 位數(shù)： | 12 |
| 采樣率（每秒）： | 40k |
| 數(shù)據(jù)接口： | 串行，SPI? |
| 轉(zhuǎn)換器數(shù)目： | 1 |
| 功率耗散（最大）： | 35mW |
| 電壓電源： | 單電源 |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 16-SOIC（0.295"，7.50mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 16-SOIC |
| 包裝： | 帶卷 (TR) |
| 輸入數(shù)目和類型： | 3 個(gè)單端，單極；3 個(gè)單端，雙極 |
ADS7812
13
SBAS042A
www.ti.com
The input impedance results from the various connections
and the internal resistor values (refer to the block diagram on
the front page of this data sheet). The internal resistor values
are typical and can change by
±30%, due to process varia-
tions. However, the ratio matching of the resistors is consid-
erably better than this. Thus, the input range will vary only
a few tenths of a percent from part to part, while the input
impedance may vary up to
±30%.
The Specifications table contains the maximum limits for
the variation of the analog input range, but only for those
ranges where the comment field shows that the offset and
gain are specified (this includes all the ranges listed in Table
I). For the other ranges, the offset and gain are not tested and
are not specified.
Five of the input ranges in Table IV are not recommended
for general use. For two of the these, the input voltage
exceeds the absolute maximum. These ranges can still be
used as long as the input voltage remains under the absolute
maximum, but this will moderately to significantly reduce
the full-scale range of the converter.
The other three input ranges involve the connection at R2IN
being driven below GND – 0.3V. This input has a reverse-
biased ESD protection diode connection to ground. If R2IN
is taken below ground, this diode will be forward-biased and
will clamp the negative input at –0.4V to –0.7V, depending
on the temperature. Here again, these ranges can still be used
at the cost of the full-scale range of the converter.
Note that Table IV assumes that the voltage at the REF pin
is 2.5V. This is true if the internal reference is being used or
if the external reference is 2.5V. Other reference voltages
will change the values in Table IV.
HIGH IMPEDANCE MODE
When R1IN, R2IN, and R3IN are connected to the analog input,
the input range of the ADS7812 is 0.3125V to 2.8125V and
the input impedance is greater than 10M
. This input range
can be used to connect the ADS7812 directly to a wide
variety of sensors. Figure 10 shows the impedance of the
sensor versus the change in ILE and DLE of the ADS7812.
The performance of the ADS7812 can be improved for higher
sensor impedance by allowing more time for acquisition. For
example, 10
s of acquisition time will approximately double
sensor impedance for the same ILE/DLE performance.
The input impedance and capacitance of the ADS7812 are
very stable with temperature. Assuming that this is true of
the sensor as well, the graph shown in Figure 10 will vary
less than a few percent over the specified temperature range
of the ADS7812. If the sensor impedance varies signifi-
cantly with temperature, the worst-case impedance should
be used.
DRIVING THE ADS7812 ANALOG INPUT
In general, any “reasonably fast”, high quality operational or
instrumentation amplifier can be used to drive the ADS7812
input. When the converter enters the acquisition mode, there
is some charge injection from the converter’s input to the
amplifier’s output. This can result in inadequate settling
time with slower amplifiers. Be very careful with single-
supply amplifiers, particularly if their output will be re-
quired to swing very close to the supply rails.
In addition, be careful in regards to the amplifier’s linearity.
The outputs of single-supply and “rail-to-rail” amplifiers
can saturate as they approach the supply rails. Rather than
the amplifier’s transfer function being a straight line, the
curve can become severely ‘S’ shaped. Also, watch for the
point where the amplifier switches from sourcing current to
sinking current. For some amplifiers, the transfer function
can be noticeably discontinuous at this point, causing a
significant change in the output voltage for a much smaller
change on the input.
Texas Instruments manufactures a wide variety of opera-
tional and instrumentation amplifiers that can be used to
drive the input of the ADS7812. These include the OPA627,
OPA134, OPA132, and INA110.
REFERENCE
The ADS7812 can be operated with its internal 2.5V refer-
ence or an external reference. By applying an external
reference voltage to the REF pin, the internal reference
voltage is overdriven. The voltage at the REF input is
internally buffered by a unity gain buffer. The output of this
buffer is present at the BUF and CAP pins.
REF
The REF pin is the output of the internal 2.5V reference or
the input for an external reference. A 1
F to 2.2F tantalum
capacitor should be connected between this pin and ground.
The capacitor should be placed as close as possible to the
ADS7812.
When using the internal reference, the REF pin should not
be connected to any type of significant load. An external
load will cause a voltage drop across the internal 4k
resistor that is in series with the internal reference. Even a
4M
external load to ground will cause a decrease in the
full-scale range of the converter by 4 LSBs.
FIGURE 10. Linearity Error vs Source Impedance in the High
Impedance Mode (R1IN = R2IN = R3IN = VIN).
LINEARITY ERROR vs SOURCE IMPEDANCE
External Source Impedance (k
)
Change
in
Worst-Case
Linearity
Error
(LSBs)
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
1
2
3
4
5
6
7
8
9 10 11 12
14 15
13
T
A = +25°C
Acquisition Time = 5s
ILE
DLE
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MS27473T16A26SLC | CONN HSG PLUG 26POS STRGHT SCKT |
| ADS7812UB/1K | IC 12BIT 35MW SER OUT A/D 16SOIC |
| MS27473T8B35SLC | CONN HSG PLUG 6POS STRGHT SCKT |
| MS27497T12B8SLC | CONN HSG RCPT 8POS WALL MT SCKT |
| MS27473T10B35A | CONN HSG PLUG 13POS STRGHT PIN |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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(fēng)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS7812UE4 | 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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS7812UG4 | 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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS7813 | 制造商:BB 制造商全稱:BB 功能描述:Low-Power, Serial 16-Bit Sampling ANALOG-TO-DIGITAL CONVERTER |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。