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参数资料
| 型号： | LTC2272CUJ#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | ADC |
| 英文描述： | 1-CH 16-BIT PROPRIETARY METHOD ADC, SERIAL ACCESS, PQCC40 |
| 封装： | 6 X 6 MM, PLASTIC, QFN-40 |
| 文件页数： | 17/44页 |
| 文件大小： | 767K |
| 代理商： | LTC2272CUJ#TR |
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LTC2273/LTC2272
24
22732fa
APPLICATIONS INFORMATION
Direct Coupled Circuits
Figure 5 demonstrates the use of a differential amplier to
convert a single ended input signal into a differential input
signal. The advantage of this method is that it provides
low frequency input response; however, the limited gain
bandwidth of any op amp or closed-loop amplier will de-
grade the ADC SFDR at high input frequencies. Additionally,
wideband op amps or differential ampliers tend to have
high noise. As a result, the SNR will be degraded unless
the noise bandwidth is limited prior to the ADC input.
Reference Operation
Figure 6 shows the LTC2273/LTC2272 reference circuitry
consisting of a 2.5V bandgap reference, a programmable
gain amplier and control circuit. The LTC2273/LTC2272
have three modes of reference operation: Internal Refer-
ence, 1.25V external reference or 2.5V external reference.
To use the internal reference, tie the SENSE pin to VDD. To
use an external reference, simply apply either a 1.25V or
2.5V reference voltage to the SENSE input pin. Both 1.25V
and 2.5V applied to SENSE will result in a full scale range
of 2.25VP-P (PGA = 0). A 1.25V output VCM is provided
for a common mode bias for input drive circuitry. An
external bypass capacitor is required for the VCM output.
This provides a high frequency low impedance path to
ground for internal and external circuitry. This is also the
compensation capacitor for the reference; it will not be
stable without this capacitor. The minimum value required
for stability is 2.2μF.
The internal programmable gain amplier provides the
internal reference voltage for the ADC. This amplier has
very stringent settling requirements and is not accessible
for external use.
The SENSE pin can be driven ±5% around the nominal 2.5V
or 1.25V external reference inputs. This adjustment range
can be used to trim the ADC gain error or other system
gain errors. When selecting the internal reference, the
SENSE pin should be tied to VDD as close to the converter
as possible. If the sense pin is driven externally it should
be bypassed to ground as close to the device as possible
with 1μF (or larger) ceramic capacitor.
PGA Pin
The PGA pin selects between two gain settings for
the ADC front-end. PGA = 0 selects an input range of
2.25VP-P; PGA = 1 selects an input range of 1.5VP-P. The
2.25V input range has the best SNR; however, the distor-
tion will be higher for input frequencies above 100MHz.
For applications with high input frequencies, the low
input range will have improved distortion; however, the
SNR will be 2.4dB worse. See the Typical Performance
Characteristics section of this datasheet.
Figure 5. DC Coupled Input with Differential Amplier
–
+
AIN
+
AIN
–
2.2μF
12pF
VCM
LTC2273/
LTC2272
ANALOG
INPUT
22732 F05
CM
AMPLIFIER = LTC6600-20,
LTC1993, ETC.
HIGH SPEED
DIFFERENTIAL
AMPLIFIER
25Ω
1x OR 2x
1.25V
SENSE
VCM
BUFFER
INTERNAL
ADC
REFERENCE
RANGE
SELECT
AND GAIN
CONTROL
2.5V
BANDGAP
REFERENCE
2.2μF
TIE TO VDD TO USE
INTERNAL 2.5V
REFERENCE
OR INPUT FOR
EXTERNAL 2.5V
REFERENCE
OR INPUT FOR
EXTERNAL 1.25V
REFERENCE
22732 F06
LTC2273/LTC2272
Figure 6. Reference Circuit
相关PDF资料 |
PDF描述 |
|---|---|
| LTC2272IUJ | 1-CH 16-BIT PROPRIETARY METHOD ADC, SERIAL ACCESS, PQCC40 |
| LTC2273CUJ#TR | 1-CH 16-BIT PROPRIETARY METHOD ADC, SERIAL ACCESS, PQCC40 |
| LTC2272CUJ | 1-CH 16-BIT PROPRIETARY METHOD ADC, SERIAL ACCESS, PQCC40 |
| LTC2273CUJ | 1-CH 16-BIT PROPRIETARY METHOD ADC, SERIAL ACCESS, PQCC40 |
| LTC2272IUJ#TR | 1-CH 16-BIT PROPRIETARY METHOD ADC, SERIAL ACCESS, PQCC40 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC2272CUJ-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:16-Bit, 80Msps/65Msps Serial Output ADC |
| LTC2272IUJ | 制造商:LINER 制造商全称:Linear Technology 功能描述:16-Bit, 80Msps/65Msps Serial Output ADC |
| LTC2272IUJ#PBF | 制造商:Linear Technology 功能描述:IC ADC 16BIT 65MSPS 40-QFN |
| LTC2272IUJ#TRPBF | 制造商:Linear Technology 功能描述:IC ADC 16BIT 65MSPS 40-QFN |
| LTC2272IUJ-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:16-Bit, 80Msps/65Msps Serial Output ADC |
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