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參數(shù)資料
| 型號： | MAX128 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Multirange, +5V, 12-Bit DAS with 2-Wire Serial Interface |
| 中文描述： | 多量程、+5V、12位DAS，2線串行接口 |
| 文件頁數(shù)： | 9/16頁 |
| 文件大?。?/td> | 124K |
| 代理商： | MAX128 |
M
Multirange, +5V, 12-Bit DAS with
2-Wire S erial Interfac e
_______________________________________________________________________________________
9
Detailed Desc ription
Converter Operation
The MAX127/MAX128 multirange, fault-tolerant ADCs
use successive approximation and internal track/hold
(T/H) circuitry to convert an analog signal to a 12-bit
digital output. Figure 1 shows the block diagram for
these devices.
Analog-Input T rac k/Hold
The T/H circuitry enters its tracking/acquisition mode on
the falling edge of the sixth clock in the 8-bit input con-
trol word and enters its hold/conversion mode when the
master issues a STOP condition. For timing information,
see the
Start a Conversionsection.
Input Range and Protec tion
The MAX127/MAX128 have software-selectable input
ranges. Each analog input channel can be indepen-
dently programmed to one of four ranges by setting the
appropriate control bits (RNG, BIP) in the control byte
(Table 1). The MAX127 has selectable input ranges
extending to ±10V (±V
REF
x 2.441), while the MAX128
has selectable input ranges extending to ±V
REF
. Note
that when an external reference is applied at REFADJ ,
the voltage at REF is given by V
REF
= 1.638 x V
REFADJ
(2.4 < V
REF
< 4.18). Figure 2 shows the equivalent
input circuit.
A resistor network on each analog input provides a
±16.5V fault protection for all channels. This circuit lim-
its the current going into or out of the pin to less than
1.2mA, whether or not the channel is on. This provides
an added layer of protection when momentary over-
voltages occur at the selected input channel, and when
a negative signal is applied at the input even though
the device may be configured for unipolar mode.
Overvoltage protection is active even if the device is in
power-down mode or V
DD
= 0.
Digital Interfac e
The MAX127/MAX128 feature a 2-wire serial interface
consisting of the SDA and SCL pins. SDA is the data
I/O and SCL is the serial clock input, controlled by the
master device. A2–A0 are used to program the
MAX127/MAX128 to different slave addresses. (The
MAX127/MAX128 only work as slaves.) The two bus
lines (SDA and SCL) must be high when the bus is not
in use. External pull-up resistors (1k
or greater) are
required on SDA and SCL to maintain I
2
C compatibility.
Table 1 shows the input control-byte format.
Figure 1. Block Diagram
CH2
CH3
CH4
CH5
CH6
CH7
REF
CH1
CH0
SHDN
REFADJ
V
DD
AGND
DGND
MAX127
MAX128
12-BIT SAR ADC
IN
REF
CLOCK
OUT
T/H
2.5V
REFERENCE
ANALOG
INPUT
MUX
AND SIGNAL
CONDITIONING
A
=
1.638
INT
CLOCK
SDA
A2
A1
A0
SCL
SERIAL INTERFACE LOGIC
10k
Figure 2. Equivalent Input Circuit
5.12k
R2
R1
CH_
S1
S2
S3
S4
BIPOLAR
UNIPOLAR
VOLTAGE
REFERENCE
T/H
OUT
HOLD
TRACK
TRACK
HOLD
OFF
ON
C
HOLD
S1 = BIPOLAR/UNIPOLAR SWITCH
S2 = INPUT MUX SWITCH
S3, S4 = T/H SWITCH
R1 = 12.5k
(MAX127) OR 5.12k
(MAX128)
R2 = 8.67k
(MAX127) OR
∞
(MAX128)
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| MAX1280BCUP | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Integrated Circuits (ICs) 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 |
| MAX1280BCUP+ | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 8Ch 400ksps 5.5V Precision 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 |
| MAX1280BCUP+T | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 8Ch 400ksps 5.5V Precision 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 |
| MAX1280BCUP-T | 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 |
| MAX1280BEUP | 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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