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参数资料
| 型号： | MAX149BEAP+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 22/23页 |
| 文件大小： | 0K |
| 描述： | IC ADC 10BIT SERIAL 20-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,000 |
| 位数： | 10 |
| 采样率（每秒）： | 133k |
| 数据接口： | MICROWIRE?，QSPI?，串行，SPI? |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 640mW |
| 电压电源： | 单电源 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-SSOP（0.209"，5.30mm 宽） |
| 供应商设备封装： | 20-SSOP |
| 包装： | 带卷 (TR) |
| 输入数目和类型： | 8 个单端，单极；8 个单端，双极；4 个差分，单极；4 个差分，双极 |
+2.7V to +5.25V, Low-Power, 8-Channel,
Serial 10-Bit ADCs
MAX148/MAX149
8
Detailed Description
The MAX148/MAX149 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 10-bit digital output. A flexible
serial interface provides easy interface to microproces-
sors (FPs). Figure 3 is a block diagram of the MAX148/
MAX149.
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 following
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 stable
within Q0.5 LSB (Q0.1 LSB for best results) with respect
to AGND during a conversion. To accomplish this, con-
nect a 0.1FF capacitor from IN- (the selected analog
input) to AGND.
During the acquisition interval, the channel selected as
the positive input (IN+) charges capacitor CHOLD. 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 acquisi-
tion interval, the T/H switch opens, retaining charge on
CHOLD as a sample of the signal at IN+.
The conversion interval begins with the input multiplexer
switching CHOLD from the positive input (IN+) to the
negative input (IN-). In single-ended mode, IN- is simply
COM. This unbalances node ZERO at the comparator’s
input. The capacitive DAC adjusts during the remainder
of the conversion cycle to restore node ZERO to 0 within
the limits of 10-bit resolution. This action is equivalent to
transferring a 16pF x [(VIN+) - (VIN-)] charge from CHOLD
to the binary-weighted capacitive DAC, which in turn
forms a digital representation of the analog input signal.
Track/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
CHOLD charges to the input signal.
The time required for the T/H to acquire an input signal
is a function of how quickly its input capacitance is
charged. If the input signal’s source impedance is high,
the acquisition time lengthens, and more time must be
Figure 3. Block Diagram
Figure 4. Equivalent Input Circuit
CS
SHDN
SCLK
DIN
CH0
1
18
15
16
20
14
13
19
INPUT
SHIFT
REGISTER
OUTPUT
SHIFT
REGISTER
ANALOG
INPUT
MUX
CLOCK
IN 10+2-BIT
SAR
ADC
+1.21V
REFERENCE
(MAX149)
REF
OUT
T/H
CONTROL
LOGIC
INT
CLOCK
17
10
2
3
4
5
6
7
8
9
12
11
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
DOUT
SSTRB
VDD
DGND
AGND
+2.500V
20k
*A
≈ 2.00 (MAX148)
A
≈ 2.06*
REFADJ
VREF
MAX148
MAX149
COM
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
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 TO THE SELECTED
IN- CHANNEL.
COMPARATOR
CAPACITIVE DAC
CSWITCH
TRACK
T/H
SWITCH
RIN
9k
CHOLD
HOLD
VREF
ZERO
16pF
INPUT
MUX
-
+
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX149BEAP-TG071 | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX149BEPP | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX149BEPP+ | 功能描述:模数转换器 - ADC 10-Bit 8Ch 133ksps 5.25V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX149BMAP/PR | 功能描述:模数转换器 - ADC 10-Bit 8Ch 133ksps 5.25V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX149BMAP/PR2 | 制造商:Maxim Integrated Products 功能描述:A/D CONVERTER, 10-BIT, SERIAL, 8-CHANNEL - Rail/Tube |
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