參數(shù)資料
型號(hào): LTC2157CUP-14#PBF
廠商: LINEAR TECHNOLOGY CORP
元件分類(lèi): ADC
英文描述: 2-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC64
封裝: 9 X 9 MM, LEAD FREE, PLASTIC, MO-220WNJR-5, QFN-64
文件頁(yè)數(shù): 14/32頁(yè)
文件大?。?/td> 647K
代理商: LTC2157CUP-14#PBF
21
21576514f
LTC2157-14/
LTC2156-14/LTC2155-14
Figure 12. Functional Equivalent of Digital Output Randomizer
Figure 13. Decoding a Randomized Digital
Output Signal
APPLICATIONS INFORMATION
DATA FORMAT
Table 1 shows the relationship between the analog input
voltage, the digital data output bits and the overflow bit.
By default the output data format is offset binary. The 2’s
complement format can be selected by serially program-
ming mode control register A4.
Table 1. Output Codes vs Input Voltage
AIN+ – AIN–
(1.5V Range)
OF
D13-D0
(OFFSET BINARY)
D13-D0
(2’s COMPLEMENT)
>0.75 V
+0.75V
+0.749908V
1
0
11 1111 1111 1111
11 1111 1111 1110
01 1111 1111 1111
01 1111 1111 1110
+0.0000915V
+0.000000V
–0.0000915V
–0.0001831V
0
10 0000 0000 0001
10 0000 0000 0000
01 1111 1111 1111
01 1111 1111 1110
00 0000 0000 0001
00 0000 0000 0000
11 1111 1111 1111
11 1111 1111 1110
–0.7499084V
–0.75V
< –0.75V
0
1
00 0000 0000 0001
00 0000 0000 0000
10 0000 0000 0001
10 0000 0000 0000
Digital Output Randomizer
Interference from the A/D digital outputs is sometimes
unavoidable. Digital interference may be from capacitive or
inductive coupling or coupling through the ground plane.
Even a tiny coupling factor can cause unwanted tones
in the ADC output spectrum. By randomizing the digital
output before it is transmitted off chip, these unwanted
tones can be randomized which reduces the unwanted
tone amplitude.
The digital output is randomized by applying an exclu-
sive-OR logic operation between the LSB and all other
data output bits. To decode, the reverse operation is
applied—an exclusive-OR operation is applied between
the LSB and all other bits. The LSB, OF and CLKOUT out-
puts are not affected. The output randomizer is enabled
by serially programming mode control register A4.
CLKOUT
OF
D13/D0
D12/D0
D1/D0
D0
21576514 F12
OF
D13
D12
D1
D0
RANDOMIZER
ON
D13
FPGA
PC BOARD
D12
D1
D0
21576514 F13
D0
D1/D0
D12/D0
D13/D0
OF
CLKOUT
LTC2157-14
相關(guān)PDF資料
PDF描述
LTC2157CUP-14#TRPBF 2-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC64
LTC2157IUP-14#PBF 2-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC64
LTC2155IUP-14#TRPBF 2-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC64
LTC2156IUP-14#PBF 2-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC64
LTC2155CUP-14#PBF 2-CH 14-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQCC64
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