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參數(shù)資料
| 型號： | ADS7870EA |
| 英文描述： | 12-Bit ADC, MUX, PGA and Internal Reference DATA ACQUISITION SYSTEM |
| 中文描述： | 12位ADC，復用器，PGA和內(nèi)部基準數(shù)據(jù)采集系統(tǒng) |
| 文件頁數(shù)： | 26/27頁 |
| 文件大?。?/td> | 262K |
| 代理商： | ADS7870EA |
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26
ADS7870
APPLICATIONS
REQUIRED SUPPORT ELEMENTS
As with any precision analog integrated circuit, good power
supply bypassing is required. A low ESR ceramic capacitor in
parallel with a large value electrolytic across the supply line
will furnish the required performance. Typical values are
0.1
μ
F and 10
μ
F respectfully.
Noise performance of the internal voltage reference circuit is
improved if a ceramic capacitor of approximately 0.01
μ
F is
connected from V
REF
to ground. Increasing the value of this
capacitor may bring slight improvement in the noise on V
REF
but will increase the time required to stabilize after turn on.
If the internal buffer amplifier is used it must have an output
filter capacitor connected to ground to ensure stability. A
nominal value of 0.47
μ
F provides the best performance. Any
value between 0.1
μ
F and 10
μ
F is acceptable. In installations
where one ADS7870 buffer is used to drive several devices an
additional filter capacitor of 0.1
μ
F should be installed at each
of the slave devices.
Pin 15 is specified as a no-connect pin. The circuit is used in
manufacture and should either be left open or connected to
ground. There will be no significant current flow through it.
The circuit in Figure 17 shows a typical installation with all
control functions under control of the host embedded control-
ler. The SCLK is active on the falling edge. If the internal
voltage reference and oscillator are used, they must be turned
on by setting the corresponding control bits in the device
registers. These registers must be set on power up and after
any reset operation.
MICRO-CONTROLLER CONNECTIONS
The ADS7870 is quite flexible in interfacing to various
micro-controllers. Connections using the hardware mode of
two types of controllers (Motorola M68HC11, Intel 80C51)
are described below.
Motorola M68HC11 (SPI)
The Motorola M68HC11 has a three-wire (four if you count
the slave select) serial interface that is commonly referred to
as SPI. (Serial Peripheral Interface) where the data is trans-
mitted MSB first. This interface is usually described as the
micro-controller and the peripheral each having two 8-bit
shift registers (one for receiving and one for transmitting.)
The transmit shift register of the micro-controller and the
receive shift register of the peripheral are connected to-
gether and vice versa. SCK controls the shift registers. SPI
is capable of full duplex operation (simultaneous read and
write.) The ADS7870 will not support full duplex operation.
The ADS7870 can only be written to or read from. It cannot
do both simultaneously.
Since the M68HC11 can configure SCK to have either
rising or falling edge active, the RISE/FALL pin on the
ADS7870 can be in which ever state is appropriate for the
desired mode of operation of the M68HC11 for compatibil-
ity with other peripherals.
In the Interface Configuration Register (Table XI), the 2W
bit should be cleared (default). The LSB bit should be clear
(default.) The 8051 bit should also be clear (default.) Since
the ADS7870 will default to SPI mode, the M68HC11
should not need to initialize the ADS7870 Interface Con-
figuration Register after power-on or reset.
RESET
RISE/FALL
CS
SCLK
D
IN
D
OUT
OSC_CTRL
CCLK
CONVERT
BUSY
V
REF
BUF
IN
BUF
OUT
/REF
IN
NC
V
DD
GND
D100
D101
D102
D103
LN0
LN1
LN2
LN3
LN4
LN5
LN6
LN7
9
10
23
20
21
22
18
19
16
17
26
27
28
15
24
25
11
12
13
14
1
2
3
4
5
6
7
8
ADS7870
0.01
μ
P
V
DD
10
μ
P
Digital I/O - 4 Lines
Analog In - 8 Lines
Serial
Interface
0.01
μ
P
0.47
μ
P
FIGURE 17. Typical Operation with Recommended Capacitor Values.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS7870EA/1K | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit ADC MUX PGA 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 |
| ADS7870EA/1KG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit ADC MUX PGA 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 |
| ADS7870EA/250 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog-to-Digital Converter， 12-Bit |
| ADS7870EAG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit ADC MUX PGA 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 |
| ADS7870EVM | 功能描述:數(shù)據(jù)轉(zhuǎn)換 IC 開發(fā)工具 ADS7870 Eval Mod RoHS:否 制造商:Texas Instruments 產(chǎn)品:Demonstration Kits 類型:ADC 工具用于評估:ADS130E08 接口類型:SPI 工作電源電壓:- 6 V to + 6 V |
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