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參數(shù)資料
型號: XE8805AMI028LF
廠商: Semtech
文件頁數(shù): 16/156頁
文件大?。?/td> 0K
描述: IC DAS 16BIT FLASH 8K MTP 64LQFP
標(biāo)準(zhǔn)包裝: 160
系列: XE880x
應(yīng)用: 感測機
核心處理器: Coolrisc816?
程序存儲器類型: 閃存(22 kB)
控制器系列: XE8000
RAM 容量: 512 x 8
接口: UART,USRT
輸入/輸出數(shù): 24
電源電壓: 2.4 V ~ 5.5 V
工作溫度: -40°C ~ 85°C
安裝類型: 表面貼裝
封裝/外殼: 64-LQFP
包裝: 托盤
供應(yīng)商設(shè)備封裝: 64-LQFP(10x10)
產(chǎn)品目錄頁面: 585 (CN2011-ZH PDF)
配用: XE8000MP-ND - PROG BOARD AND PROSTART2 CARD
Semtech 2006
www.semtech.com
16-26
XE8805/05A
Figure 16-16. Differential non-linearity of the ADC converter.
16.8.4
Noise
Ideally, a constant input voltage VIN should result in a constant output code. However, because of circuit noise, the
output code may vary for a fixed input voltage. Thus, a statistical analysis on the output code of 1200 conversions
for a constant input voltage was performed to derive the equivalent noise levels of PGA1, PGA2, and PGA3. The
extracted rms output noise of PGA1, 2, and 3 are given in Table 16-27: standard output deviation and output rms
noise voltage. Figure 16-17 shows the distribution for the ADC alone (PGA1, 2, and 3 bypassed). Quantization
noise is dominant in this case, and, thus, the ADC thermal noise is below 16 bits.
The simple noise model of Figure 16-18(a) is used to estimate the equivalent input referred rms noise VN,IN of the
acquisition chain in the model of Figure 16-18(b). This is given by the relationship:
)
(
))
/(
(
))
/(
(
)
/
(
2
3
2
1
3
2
1
2
1
2
,
ELCONV
N
IN
N
OSR
GD
V
GD
V
GD
V
+
+
=
(V
2rms)
(Eq. 21)
where VN1, VN2, and VN3 are the output rms noise figures of Table 16-27, GD1, GD2, and GD3 are the PGA gains of
stages 1 to 3 respectively. As shown in this equation, noise can be reduced by increasing OSR and NELCONV
(increases the ADC averaging effect, but reduces noise).
Parameter
PGA1
PGA2
PGA3
Standard deviation at
ADC output (LSB)
0.85
1.4
1.5
Output rms noise (
V)
1
205 (VN1)
340 (VN2)
365 (VN3)
Note: see noise model of Figure 16-18 and equation Eq. 21.
Table 16-27. PGA noise measurements (n = 16 bits, OSR = 512, NELCONV = 2, VREF = 5V)
Not
Recommended
for
New
Designs
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