参数资料
型号: AD9248BCPZRL-65
厂商: Analog Devices Inc
文件页数: 14/48页
文件大小: 0K
描述: IC ADC 14BIT DUAL 65MSPS 64LFCSP
标准包装: 2,500
位数: 14
采样率(每秒): 65M
数据接口: 并联
转换器数目: 2
功率耗散(最大): 600mW
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: 64-VFQFN 裸露焊盘,CSP
供应商设备封装: 64-LFCSP-VQ(9x9)
包装: 带卷 (TR)
输入数目和类型: 4 个单端,单极;2 个差分,单极
AD9248
Rev. B | Page 21 of 48
External Reference Operation
The use of an external reference may be necessary to
enhance the gain accuracy of the ADC or to improve thermal
drift characteristics. When multiple ADCs track one another, a
single reference (internal or external) may be necessary to
reduce gain matching errors to an acceptable level. A high
precision external reference may also be selected to provide
lower gain and offset temperature drift. Figure 37 shows the
typical drift characteristics of the internal reference in both
1 V and 0.5 V modes. When the SENSE pin is tied to AVDD,
the internal reference is disabled, allowing the use of an
external reference. An internal reference buffer loads the
external reference with an equivalent 7 kΩ load. The internal
buffer still generates the positive and negative full-scale
references, REFT and REFB, for the ADC core. The input span
is always twice the value of the reference voltage; therefore, the
external reference must be limited to a maximum of 1 V. If the
internal reference of the AD9248 is used to drive multiple
converters to improve gain matching, the loading of the
reference by the other converters must be considered. Figure 38
depicts how the internal reference voltage is affected by loading.
VIN+
VIN–
VREF
REFT
SENSE
0.5V
AD9248
REFB
R1
R2
10
μF
10
μF
0.1
μF
0.1
μF
10
μF
ADC
CORE
SELECT
LOGIC
0.1
μF
04446-
035
Figure 36. Programmable Reference Configuration
TEMPERATURE (
°C)
0.2
VR
EF
ER
R
OR
(
%
)
1.2
1.0
0.8
0.6
0.4
0
–40 –30 –20 –10
0
10
20
30
40
50
60
70
80
VREF = 1V
VREF = 0.5V
04446-036
Figure 37. Typical VREF Drift
LOAD (mA)
–0.20
E
RROR
(%)
0.05
0
–0.05
–0.10
–0.15
–0.25
0
0.5
1.0
1.5
2.0
2.5
3.0
0.5V ERROR
1V ERROR
04446-037
Figure 38. VREF Accuracy vs. Load
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