參數(shù)資料
型號(hào)： MAX146ACAP
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： ADC
英文描述： .1 UF/400VDC METAL POLY CAP
中文描述： 8-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, SERIAL ACCESS, PDSO20
封裝： SSOP-20
文件頁(yè)數(shù)： 9/24頁(yè)
文件大?。?/td> 198K
代理商： MAX146ACAP
M
+2.7V, Low-Power, 8-Channel,
S erial 12-Bit ADCs
_______________________________________________________________________________________
9
_______________Detailed Desc ription
The MAX146/MAX147 analog-to-digital converters
(ADCs) use a successive-approximation conversion
technique and input track/hold (T/H) circuitry to convert
an analog signal to a 12-bit digital output. A flexible ser-
ial interface provides easy interface to microprocessors
(μPs). Figure 3 is a block diagram of the MAX146/
MAX147.
Pseudo-Differential Input
The sampling architecture of the ADC’s analog com-
parator is illustrated in the equivalent input circuit
(Figure 4). In single-ended mode, IN+ is internally
switched to CH0–CH7, and IN- is switched to COM. In
differential mode, IN+ and IN- are selected from the fol-
lowing pairs: CH0/CH1, CH2/CH3, CH4/CH5, and
CH6/CH7. Configure the channels with Tables 2 and 3.
In differential mode, IN- and IN+ are internally switched
to either of the analog inputs. This configuration is
pseudo-differential to the effect that only the signal at
IN+ is sampled. The return side (IN-) must remain sta-
ble within ±0.5LSB (±0.1LSB for best results) with
respect to AGND during a conversion. To accomplish
this, connect a 0.1μF capacitor from IN- (the selected
analog input) to AGND.
During the acquisition interval, the channel selected as
the positive input (IN+) charges capacitor C
HOLD
. The
acquisition interval spans three SCLK cycles and ends
on the falling SCLK edge after the last bit of the input
control word has been entered. At the end of the acqui-
sition interval, the T/H switch opens, retaining charge
on C
HOLD
as a sample of the signal at IN+.
The conversion interval begins with the input multiplex-
er switching C
HOLD
from the positive input (IN+) to the
negative input (IN-). In single-ended mode, IN- is sim-
ply COM. This unbalances node ZERO at the compara-
tor’s input. The capacitive DAC adjusts during the
remainder of the conversion cycle to restore node
ZERO to 0V within the limits of 12-bit resolution. This
action is equivalent to transferring a 16pF x [(V
IN
+
) -
(V
IN
-)] charge from C
HOLD
to the binary-weighted
capacitive DAC, which in turn forms a digital represen-
tation of the analog input signal.
T rac k/Hold
The T/H enters its tracking mode on the falling clock
edge after the fifth bit of the 8-bit control word has been
shifted in. It enters its hold mode on the falling clock
edge after the eighth bit of the control word has been
shifted in. If the converter is set up for single-ended
inputs, IN- is connected to COM, and the converter
samples the “+” input. If the converter is set up for dif-
ferential inputs, IN- connects to the “-” input, and the
difference of
|
IN+ - IN-
|
is sampled. At the end of the
conversion, the positive input connects back to IN+,
and C
HOLD
charges to the input signal.
INPUT
SHIFT
REGISTER
CONTROL
LOGIC
INT
CLOCK
OUTPUT
SHIFT
REGISTER
+1.21V
REFERENCE
(MAX146)
T/H
ANALOG
INPUT
MUX
12-BIT
SAR
ADC
REF
IN
DOUT
SSTRB
V
DD
DGND
AGND
SCLK
DIN
COM
REFADJ
VREF
OUT
CLOCK
+2.500V
20k
*A
≈
2.00 (MAX147)
10
11
12
9
15
16
17
18
19
CH6
CH7
7
8
CH4
CH5
5
6
CH1
CH2
CH3
2
3
4
CH0
1
MAX146
MAX147
CS
SHDN
20
14
13
≈
2.06*
A
Figure 3. Block Diagram
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
C
SWITCH
TRACK
T/H
SWITCH
R
IN
9k
C
HOLD
HOLD
12-BIT CAPACITIVE DAC
VREF
ZERO
COMPARATOR
–
+
16pF
SINGLE-ENDED MODE: IN+ = CH0–CH7, IN- = COM.
DIFFERENTIAL MODE: IN+ AND IN- SELECTED FROM PAIRS OF
CH0/CH1, CH2/CH3, CH4/CH5, AND CH6/CH7.
AT THE SAMPLING INSTANT,
THE MUX INPUT SWITCHES
FROM THE SELECTED IN+
CHANNEL TOTHE SELECTED
IN- CHANNEL.
INPUT
MUX
Figure 4. Equivalent Input Circuit
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX146ACAP+ 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 8Ch 133ksps 3.6V 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
MAX146ACAP+T 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 8Ch 133ksps 3.6V 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
MAX146ACAP-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
MAX146ACPP 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
MAX146ACPP+ 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 8Ch 133ksps 3.6V 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
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