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参数资料
| 型号： | MAX1257BETM+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/43页 |
| 文件大小： | 0K |
| 描述： | IC ADC/DAC 12BIT 48-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | ADC，DAC |
| 分辨率（位）： | 12 b |
| 采样率（每秒）： | 225k |
| 数据接口： | 串行 |
| 电压电源： | 模拟和数字 |
| 电源电压： | 2.7 V ~ 3.6 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 48-WFQFN 裸露焊盘 |
| 供应商设备封装： | 48-TQFN-EP（7x7） |
| 包装： | 带卷 (TR) |
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MAX1220/MAX1257/MAX1258
12-Bit, Multichannel ADCs/DACs with FIFO,
Temperature Sensing, and GPIO Ports
______________________________________________________________________________________
21
See Tables 5–8 for more details on configuring the
inputs. For the inputs that are configurable as CNVST,
REF2, and an analog input, only one function can be
used at a time.
Unipolar or Bipolar Conversions
Address the unipolar- and bipolar-mode registers
through the setup register (bits 1 and 0). See Table 5 for
the setup register. See Figures 3 and 4 for the transfer-
function graphs. Program a pair of analog inputs for dif-
ferential operation by writing a one to the appropriate bit
of the bipolar- or unipolar-mode register. Unipolar mode
sets the differential input range from 0 to VREF1. A nega-
tive differential analog input in unipolar mode causes the
digital output code to be zero. Selecting bipolar mode
sets the differential input range to ±VREF1 / 2. The digital
output code is binary in unipolar mode and two’s com-
plement in bipolar mode.
In single-ended mode, the MAX1220/MAX1257/
MAX1258 always operate in unipolar mode. The analog
inputs are internally referenced to AGND with a full-scale
input range from 0 to the selected reference voltage.
Analog Input (T/H)
The equivalent circuit of Figure 2 shows the ADC input
architecture of the MAX1220/MAX1257/MAX1258. In
track mode, a positive input capacitor is connected to
AIN0–AIN15 in single-ended mode and AIN0, AIN2,
and AIN4–AIN14 (only positive inputs) in differential
mode. A negative input capacitor is connected to
AGND in single-ended mode or AIN1, AIN3, and
AIN5–AIN15 (only negative inputs) in differential mode.
For external T/H timing, use clock mode 01. After the
T/H enters hold mode, the difference between the sam-
pled positive and negative input voltages is converted.
The input capacitance charging rate determines the
time required for the T/H to acquire an input signal. If
the input signal’s source impedance is high, the
required acquisition time lengthens.
Any source impedance below 300
does not signifi-
cantly affect the ADC’s AC performance. A high-imped-
ance source can be accommodated either by
lengthening tACQ (only in clock mode 01) or by placing
a 1F capacitor between the positive and negative ana-
log inputs. The combination of the analog-input source
impedance and the capacitance at the analog input cre-
ates an RC filter that limits the analog input bandwidth.
Input Bandwidth
The ADC’s input-tracking circuitry has a 1MHz small-
signal bandwidth, making it possible to digitize high-
speed transient events and measure periodic signals
with bandwidths exceeding the ADC’s sampling rate by
using undersampling techniques. Anti-alias prefiltering
of the input signals is necessary to avoid high-frequen-
cy signals aliasing into the frequency band
of interest.
Analog Input Protection
Internal electrostatic-discharge (ESD) protection diodes
clamp all analog inputs to AVDD and AGND, allowing
the inputs to swing from (AGND - 0.3V) to (AVDD +
0.3V) without damage. However, for accurate conver-
sions near full scale, the inputs must not exceed AVDD
by more than 50mV or be lower than AGND by 50mV. If
an analog input voltage exceeds the supplies, limit the
input current to 2mA.
Internal FIFO
The MAX1220/MAX1257/MAX1258 contain a first-
in/first-out (FIFO) buffer that holds up to 16 ADC results
plus one temperature result. The internal FIFO allows
the ADC to process and store multiple internally
clocked conversions and a temperature measurement
without being serviced by the serial bus.
If the FIFO is filled and further conversions are request-
ed without reading from the FIFO, the oldest ADC
results are overwritten by the new ADC results. Each
result contains 2 bytes, with the MSB preceded by four
leading zeros. After each falling edge of CS, the oldest
available pair of bytes of data is available at DOUT,
MSB first. When the FIFO is empty, DOUT is zero.
AIN0–AIN15
(SINGLE-ENDED),
AIN0, AIN2,
AIN4–AIN14
(DIFFERENTIAL)
COMPARATOR
HOLD
ACQ
HOLD
ACQ
HOLD
AVDD / 2
REF1
AGND
CIN+
CIN-
DAC
AGND
(SINGLE-ENDED),
AIN1, AIN3,
AIN5–AIN15
(DIFFERENTIAL)
Figure 2. Equivalent Input Circuit
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相关代理商/技术参数 |
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| MAX1257EVKIT | 功能描述:数据转换 IC 开发工具 Programmers, Development Systems RoHS:否 制造商:Texas Instruments 产品:Demonstration Kits 类型:ADC 工具用于评估:ADS130E08 接口类型:SPI 工作电源电压:- 6 V to + 6 V |
| MAX1258BETM | 功能描述:ADC / DAC多通道 RoHS:否 制造商:Texas Instruments 转换速率: 分辨率:8 bit 接口类型:SPI 电压参考: 电源电压-最大:3.6 V 电源电压-最小:2 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-40 |
| MAX1258BETM+ | 功能描述:ADC / DAC多通道 12-Bit 16Ch 300ksps 5.5V Precision ADC RoHS:否 制造商:Texas Instruments 转换速率: 分辨率:8 bit 接口类型:SPI 电压参考: 电源电压-最大:3.6 V 电源电压-最小:2 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-40 |
| MAX1258BETM+T | 功能描述:ADC / DAC多通道 12-Bit 16Ch 300ksps 5.5V Precision ADC RoHS:否 制造商:Texas Instruments 转换速率: 分辨率:8 bit 接口类型:SPI 电压参考: 电源电压-最大:3.6 V 电源电压-最小:2 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-40 |
| MAX1258BETM-T | 功能描述:ADC / DAC多通道 RoHS:否 制造商:Texas Instruments 转换速率: 分辨率:8 bit 接口类型:SPI 电压参考: 电源电压-最大:3.6 V 电源电压-最小:2 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-40 |
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