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參數(shù)資料
| 型號： | AD7822 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 1-Channel Sampling ADCs(2MSPS,單通道采樣8位A/D轉換器) |
| 中文描述： | 單通道采樣ADC（2MSPS，單通道采樣8位的A / D轉換器） |
| 文件頁數(shù)： | 11/20頁 |
| 文件大?。?/td> | 238K |
| 代理商： | AD7822 |
AD7822/AD7825/AD7829
–11–
REV. 0
Figure 16 shows how to power up the AD7822 or AD7825
when V
DD
is first connected or after the ADCs have been pow-
ered down using the
PD
pin, or the
CONVST
pin, with either
the on-chip or an external reference. When the supplies are first
connected or after the part has been powered down by the
PD
pin, only a rising edge on the
PD
pin will cause the part to
power up. When the part has been powered down using the
CONVST
pin, a rising edge on either the
PD
pin or the
CONVST
pin will power the part up again.
As with the AD7829, when using an external reference with the
AD7822 or AD7825, the falling edge of
CONVST
may occur
before the required power-up time has elapsed, however, if this
is the case, the conversion will not be initiated on the falling
edge of
CONVST
, but rather at the moment when the part has
powered up completely, i.e., after 1
μ
s. If the falling edge of
CONVST
occurs after the required power-up time has elapsed,
it is upon this falling edge that a conversion is initiated. When
using the on-chip reference it is necessary to wait the required
power-up time of approximately 25
μ
s before initiating a conver-
sion; i.e., a falling edge on
CONVST
may not occur before the
required power-up time has elapsed, when supplies are first
connected to the AD7822 or AD7825, or when the ADCs have
been powered down using the PD pin or the
CONVST
pin as
shown in Figure 16.
V
DD
PD
CONVST
t
POWER-UP
1
m
s
t
POWER-UP
1
m
s
CONVERSION INITIATED HERE
CONVERSION INITIATED HERE
V
DD
PD
CONVST
t
POWER-UP
25
m
s
t
POWER-UP
25
m
s
CONVERSION INITIATED HERE
CONVERSION INITIATED HERE
EXTERNAL REFERENCE
ON-CHIP REFERENCE
Figure 16. AD7822/AD7825 Power-Up Time
POWE R VS. T HROUGHPUT
Superior power performance can be achieved by using the auto-
matic power-down (Mode 2) at the end of a conversion—see
Operating Modes section of the data sheet.
Figure 17 shows how the automatic power-down is implemented
using the
CONVST
signal to achieve the optimum power per-
formance for the AD7822, AD7825 and AD7829. T he duration
of the
CONVST
pulse is set to be equal to or less than the
power-up time of the devices—see Operating Modes section. As
the throughput rate is reduced, the device remains in its power-
down state longer and the average power consumption over time
drops accordingly.
t
POWER-UP
1
m
s
330ns
t
CONVERT
POWER-DOWN
t
CYCLE
10
m
s @ 100kSPS
CONVST
Figure 17. Automatic Power-Down
For example, if the AD7822 is operated in a continuous sam-
pling mode, with a throughput rate of 100 kSPS and using an
external reference, the power consumption is calculated as fol-
lows. T he power dissipation during normal operation is 36 mW,
V
DD
= 3 V. If the power-up time is 1
μ
s and the conversion time
is 330 ns (@ +25
°
C), the AD7822 can be said to dissipate
36 mW for 1.33
μ
s (worst case) during each conversion cycle.
If the throughput rate is 100 kSPS, the cycle time is 10
μ
s
and the average power dissipated during each cycle is
(1.33/10)
×
(36 mW) = 4.79 mW.
Figure 18 shows the power vs. throughput rate for automatic
full power-down.
THROUGHPUT – kSPS
100
10
00
500
100
P
1
200
300
400
0.1
50
150
250
350
450
Figure 18. AD7822/AD7825/AD7829 Power vs. Throughput
FREQUENCY – kHz
0
–10
–80
d
–40
–50
–60
–70
–20
–30
0
1
1
1
1
2
2
2
3
3
3
3
4
4
4
5
5
5
5
6
6
6
7
7
7
7
8
8
8
9
9
9
2
5
8
9
2048 POINT FFT
SAMPLING
2MSPS
F
IN
= 200kHz
Figure 19. AD7822/AD7825/AD7829 SNR
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|---|---|
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| AD7822_06 | 制造商:AD 制造商全稱:Analog Devices 功能描述:3 V/5 V, 2 MSPS, 8-Bit, 1-/4-/8-Channel Sampling ADCs |
| AD7822BN | 制造商:Analog Devices 功能描述:ADC Single Semiflash 2Msps 8-bit Parallel 20-Pin PDIP N 制造商:Rochester Electronics LLC 功能描述:8-BIT 2MSPS PARALLEL OUTPUT ADC. I.C. - Bulk 制造商:Analog Devices 功能描述:IC 8BIT ADC 7822 DIP20 |
| AD7822BNZ | 功能描述:IC ADC 8BIT 1CHAN 2MSPS 20DIP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉換器 系列:- 其它有關文件:TSA1204 View All Specifications 標準包裝:1 系列:- 位數(shù):12 采樣率（每秒）:20M 數(shù)據(jù)接口:并聯(lián) 轉換器數(shù)目:2 功率耗散（最大）:155mW 電壓電源:模擬和數(shù)字 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-TQFP 供應商設備封裝:48-TQFP（7x7） 包裝:Digi-Reel® 輸入數(shù)目和類型:4 個單端，單極；2 個差分，單極 產品目錄頁面:1156 (CN2011-ZH PDF) 其它名稱:497-5435-6 |
| AD7822BNZ1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:3 V/5 V, 2 MSPS, 8-Bit, 1-/4-/8-Channel Sampling ADCs |
| AD7822BR | 功能描述:IC ADC 8BIT 1CH 2MSPS 20-SOIC RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉換器 系列:- 標準包裝:1,000 系列:- 位數(shù):16 采樣率（每秒）:45k 數(shù)據(jù)接口:串行 轉換器數(shù)目:2 功率耗散（最大）:315mW 電壓電源:模擬和數(shù)字 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:28-SOIC W 包裝:帶卷 (TR) 輸入數(shù)目和類型:2 個單端，單極 |
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