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參數資料
| 型號： | AD9842AJST |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 消費家電 |
| 英文描述： | Complete 20 MSPS CCD Signal Processors |
| 中文描述： | SPECIALTY CONSUMER CIRCUIT, PQFP48 |
| 封裝： | PLASTIC, LQFP-48 |
| 文件頁數： | 20/23頁 |
| 文件大?。?/td> | 272K |
| 代理商： | AD9842AJST |
REV. 0
AD9841A/AD9842A
–20–
A/D Converter
The AD9841A and AD9842A use high-performance ADC archi-
tectures, optimized for high speed and low power. Differential
Nonlinearity (DNL) performance is typically better than 0.5 LSB,
as shown in TPCs 2 and 4. Instead of the 1 V full-scale range
used by the earlier AD9801 and AD9803 products from Analog
Devices, the AD984xA ADCs use a 2 V input range. Better
noise performance results from using a larger ADC full-scale
range (see TPCs 3 and 5).
AUX1 Mode
For applications that do not require CDS, the AD9841A/AD9842A
can be configured to sample ac-coupled waveforms. Figure 30
shows the circuit configuration for using the AUX1 channel
input (Pin 36). A single 0.1
μ
F ac-coupling capacitor is needed
between the input signal driver and the AUX1IN pin. An on-chip
dc-bias circuit sets the average value of the input signal to
approximately 0.4 V, which is referenced to the midscale code
of the ADC. The VGA Gain register provides a gain range of 0 dB
to 36 dB in this mode of operation (see VGA Gain Curve,
Figure 29). The VGA gains up the signal level with respect to
the 0.4 V bias level. Signal levels above the bias level will be
further increased to a higher ADC code, while signal levels below
the bias level will be further decreased to a lower ADC code.
AUX2 Mode
For sampling video-type waveforms, such as NTSC and PAL
signals, the AUX2 channel provides black level clamping, gain
adjustment, and A/D conversion. Figure 31 shows the circuit
configuration for using the AUX2 channel input (Pin 34). A
external 0.1
μ
F blocking capacitor is used with the on-chip video
clamp circuit, to level-shift the input signal to a desired refer-
ence level. The clamp circuit automatically senses the most
negative portion of the input signal, and adjusts the voltage
across the input capacitor. This forces the black level of the
input signal to be equal to the value programmed into the Clamp
Level register (see Serial Interface Register Description). The VGA
provides gain adjustment from 0 dB to 18 dB. The same VGA
Gain register is used, but only the 9 MSBs of the gain register
are used (see Table VIII.)
AUX1IN
0.1 F
VGA GAIN
REGISTER
ADC
VGA
10
5k
0.4V
0.4V
INPUT SIGNAL
V
0.8V
0.4V
MIDSCALE
0dB TO 36dB
Figure 30. AUX1 Circuit Configuration
0dB TO 18dB
8
AUX2IN
BUFFER
0.1 F
VIDEO
SIGNAL
9
CLAMP LEVEL
LPF
VGA GAIN
REGISTER
ADC
VGA
VIDEO CLAMP
CIRCUIT
CLAMP LEVEL
REGISTER
Figure 31. AUX2 Circuit Configuration
Table VIII. VGA Gain Register Used for AUX2-Mode
MSB
D9
LSB
D0
D10
D8
D7
D6
D5
D4
D3
D2
D1
Gain (dB)
X
0
1
X
0
X
0
X
0
X
0
1
X
0
X
0
X
0
X
0
X
0
0.0
0.0
18.0
1
1
1
1
1
1
1
1
1
相關PDF資料 |
PDF描述 |
|---|---|
| AD9843A | Complete 10-Bit 20 MSPS CCD Signal Processor |
| AD9843AJST | Complete 10-Bit 20 MSPS CCD Signal Processor |
| AD9844 | Complete 12-Bit 20 MSPS CCD Signal Processor |
| AD9844A | Complete 12-Bit 20 MSPS CCD Signal Processor |
| AD9844AJST | Complete 12-Bit 20 MSPS CCD Signal Processor |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD9842AJSTRL | 制造商:Analog Devices 功能描述:AFE Video 1ADC 10-Bit 3.3V 48-Pin LQFP T/R 制造商:Analog Devices 功能描述:AFE VID 1ADC 10-BIT 3.3V 48LQFP - Tape and Reel 制造商:Rochester Electronics LLC 功能描述:12 BIT 20 MHZ ANALOG FRONT END - Tape and Reel |
| AD9842AJSTZ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| AD9842-EB | 制造商:Analog Devices 功能描述:12 BIT 20 MHZ ANALOG FRONT END - Bulk |
| AD9843A | 制造商:AD 制造商全稱:Analog Devices 功能描述:Complete 10-Bit 20 MSPS CCD Signal Processor |
| AD9843AJST | 制造商:Analog Devices 功能描述:AFE Video 1ADC 10-Bit 3.3V 48-Pin LQFP 制造商:Analog Devices 功能描述:AFE VID 1ADC 10-BIT 3.3V 48LQFP - Bulk 制造商:Rochester Electronics LLC 功能描述:10 BIT 20 MSPS CCD SIGNAL PROCESSOR - Bulk |
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