參數(shù)資料
型號： ADS1255
英文描述： Very Low Noise, 24-Bit Analog-to-Digital Converter
中文描述： 極低噪聲，24位模擬數(shù)字轉(zhuǎn)換器
文件頁數(shù)： 16/39頁
文件大?。?/td> 427K
代理商： ADS1255
SBAS288D JUNE 2003 REVISED AUGUST 2004
www.ti.com
16
PROGRAMMABLE GAIN AMPLIFIER (PGA)
The ADS1255/6 is a very high resolution converter. To
further complement its performance, the low-noise PGA
provides even more resolution when measuring smaller
input signals. For the best resolution, set the PGA to the
highest possible setting. This will depend on the largest
input signal to be measured. The ADS1255/6 full-scale
input voltage equals
±
2V
REF
/PGA. Table 8 shows the
full-scale input voltage for the different PGA settings for
V
REF
= 2.5V. For example, if the largest signal to be
measured is 1.0V, the optimum PGA setting would be 4,
which gives a full-scale input voltage of 1.25V. Higher
PGAs cannot be used since they cannot handle a 1.0V
input signal.
Table 8. Full-Scale Input Voltage vs
PGA Setting
PGA SETTING
FULL-SCALE INPUT VOLTAGE (VREF = 2.5V)
±
5V
±
2.5V
±
1.25V
±
0.625V
±
312.5mV
±
156.25mV
±
78.125mV
1
2
4
8
16
32
64
The PGA is controlled by the ADCON register.
Recalibrating the A/D converter after changing the PGA
setting is recommended. The time required for
self-calibration is dependent on the PGA setting. See the
Calibration section for more details. The analog current
and input impedance (when the buffer is disabled) vary as
a function of PGA setting.
MODULATOR INPUT CIRCUITRY
The ADS1255/6 modulator measures the input signal
using internal capacitors that are continuously charged
and discharged. Figure 9 shows a simplified schematic of
the ADS1255/6 input circuitry with the input buffer
disabled. Figure 10 shows the on/off timings of the
switches of Figure 9. S1 switches close during the input
sampling phase. With S1 closed, C
A1
charges to AIN
P
,
C
A2
charges to AIN
N
, and C
B
charges to (AIN
P
– AIN
N
). For the
discharge phase, S1 opens first and then S2 closes. C
A1
and C
A2
discharge to approximately AVDD/2 and C
B
discharges to 0V. This two-phase sample/discharge cycle
repeats with a period of
τ
SAMPLE
. This time is a function of
the PGA setting as shown in Table 9 along with the values
of the capacitor C
A1
= C
A2
= C
A
and C
B
.
AVDD/2
AVDD/2
AINP
AINN
Input
Multiplexer
AIN0
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
AINCOM
A
O
S2
S1
S1
S2
CA1
CB
CA2
Figure 9. Simplified Input Structure
with Buffer Off
ON
OFF
ON
S
1
S
2
OFF
τ
SAMPLE
Figure 10. S1 and S2 Switch Timing for Figure 9
Table 9. Input Sampling Time,
τ
SAMPLE
, and
C
A
and C
B
vs PGA
PGA
SETTING
τ
SAMPLE(1)
fCLKIN/4 (521ns)
fCLKIN/4 (521ns)
fCLKIN/4 (521ns)
fCLKIN/4 (521ns)
fCLKIN/4 (521ns)
fCLKIN/2 (260ns)
fCLKIN/2 (260ns)
CA
2.1pF
CB
2.4pF
1
2
4.2pF
4.9pF
4
8.3pF
9.7pF
8
17pF
19pF
16
33pF
39pF
32
33pF
39pF
64
33pF
39pF
(1)
τ
SAMPLE for fCLKIN = 7.68MHz.
相關(guān)PDF資料
PDF描述
ADS1256 Very Low Noise, 24-Bit Analog-to-Digital Converter
ADS1271 24 BIT WIDE BANDWIDTH ANALOG TO DIGITAL CONVERTER
ADS1271IPW 24 BIT WIDE BANDWIDTH ANALOG TO DIGITAL CONVERTER
ADS1271IPWR 24 BIT WIDE BANDWIDTH ANALOG TO DIGITAL CONVERTER
ADS1271EVM-PDK modular EVM form factor
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ADS1255IDB 制造商:BB 制造商全稱:BB 功能描述:Very Low Noise, 24-Bit Analog-to-Digital Converter
ADS1255IDBR 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 24 Bit 30kSPS Very Lo-Noise Delta-Sigma RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
ADS1255IDBRG4 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 24 Bit 30kSPS Very Lo-Noise Delta-Sigma RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
ADS1255IDBT 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 24 Bit 30kSPS Very Lo-Noise Delta-Sigma RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
ADS1255IDBT 制造商:Texas Instruments 功能描述:ADC 24BIT 5V SPI 30MSPS 20SSOP 制造商:Texas Instruments 功能描述:ADC, 24BIT, 5V, SPI, 30MSPS, 20SSOP 制造商:Texas Instruments 功能描述:ADC, 24BIT, 5V, SPI, 30MSPS, 20SSOP; Resolution (Bits):24bit; Sampling Rate:30kSPS; Supply Voltage Type:Single; Supply Voltage Min:4.75V; Supply Voltage Max:5.25V; Supply Current:36mA; Digital IC Case Style:SSOP; No. of Pins:20; ;RoHS Compliant: Yes 制造商:Texas Instruments 功能描述:ADC, 24BIT, 5V, SPI, 30KSPS, 20SSOP ;ROHS COMPLIANT: YES
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*