参数资料
型号: MAX1238KEEE+T
厂商: Maxim Integrated Products
文件页数: 11/22页
文件大小: 0K
描述: IC ADC 12BIT SERIAL 16-QSOP
标准包装: 2,500
位数: 12
采样率(每秒): 94.4k
数据接口: I²C,串行
转换器数目: 1
功率耗散(最大): 666.7mW
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: 16-SSOP(0.154",3.90mm 宽)
供应商设备封装: 16-QSOP
包装: 带卷 (TR)
输入数目和类型: 12 个单端,单极;12 个单端,双极;6 个差分,单极;6 个差分,双极
age. Use separate analog and digital PC board ground
sections with only one star point (Figure 14) connecting
the two ground systems (analog and digital). For lowest
noise operation, ensure the ground return to the star
ground’s power supply is low impedance and as short
as possible. Route digital signals far away from sensi-
tive analog and reference inputs.
High-frequency noise in the power supply (VDD) could
influence the proper operation of the ADC’s fast com-
parator. Bypass VDD to the star ground with a network of
two parallel capacitors, 0.1F and 4.7F, located as
close as possible to the MAX1236–MAX1239 power-sup-
ply pin. Minimize capacitor lead length for best supply
noise rejection, and add an attenuation resistor (5
Ω) in
series with the power supply if it is extremely noisy.
Definitions
Integral Nonlinearity
Integral nonlinearity (INL) is the deviation of the values on
an actual transfer function from a straight line. This straight
line can be either a best straight-line fit or a line drawn
between the endpoints of the transfer function, once offset
and gain errors have been nullified. The MAX1236–
MAX1239’s INL is measured using the endpoint.
Differential Nonlinearity
Differential nonlinearity (DNL) is the difference between
an actual step width and the ideal value of 1 LSB. A
DNL error specification of less than 1 LSB guarantees
no missing codes and a monotonic transfer function.
Aperture Jitter
Aperture jitter (tAJ) is the sample-to-sample variation in
the time between the samples.
Aperture Delay
Aperture delay (tAD) is the time between the falling
edge of the sampling clock and the instant when an
actual sample is taken.
Signal-to-Noise Ratio
For a waveform perfectly reconstructed from digital sam-
ples, the theoretical maximum SNR is the ratio of the full-
scale analog input (RMS value) to the RMS quantization
error (residual error). The ideal, theoretical minimum ana-
log-to-digital noise is caused by quantization error only
and results directly from the ADC’s resolution (N Bits):
SNRMAX[dB] = 6.02dB N + 1.76dB
In reality, there are other noise sources besides quanti-
zation noise: thermal noise, reference noise, clock jitter,
etc. SNR is computed by taking the ratio of the RMS
signal to the RMS noise, which includes all spectral
components minus the fundamental, the first five har-
monics, and the DC offset.
Signal-to-Noise Plus Distortion
Signal-to-noise plus distortion (SINAD) is the ratio of the
fundamental input frequency’s RMS amplitude to the
RMS equivalent of all other ADC output signals.
MAX1236–MAX1239
2.7V to 3.6V and 4.5V to 5.5V, Low-Power,
4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
______________________________________________________________________________________
19
011 . . . 111
011 . . . 110
000 . . . 010
000 . . . 001
000 . . . 000
111 . . . 111
111 . . . 110
111 . . . 101
100 . . . 001
100 . . . 000
- FS
0
INPUT VOLTAGE (LSB)
OUTPUT CODE
ZS = 0
+FS - 1 LSB
VCOM
VREF/2
VIN = (AIN+) - (AIN-)
FS =
VREF
2
-FS =
-VREF
2
MAX1236-MAX1239
1 LSB =
VREF
4096
Figure 13. Bipolar Transfer Function
GND
VLOGIC = 3V/5V
3V OR 5V
SUPPLIES
DGND
3V/5V
GND
*OPTIONAL
4.7
μF
R* = 5
Ω
0.1
μF
VDD
DIGITAL
CIRCUITRY
MAX1236–
MAX1239
Figure 14. Power-Supply Grounding Connection
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