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參數(shù)資料
| 型號： | AD7827 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 3 V/5 V, 1 MSPS, 8-Bit, Serial Interface Sampling ADC |
| 中文描述： | 3伏/ 5伏，1 MSPS的，8位，串行接口采樣ADC |
| 文件頁數(shù)： | 8/12頁 |
| 文件大?。?/td> | 185K |
| 代理商： | AD7827 |
AD7827
–8–
REV. 0
POWE R-UP T IME S
T he AD7827 has a 1
μ
s power-up time when using an external
reference and a 25
μ
s power-up time when using the on-chip
reference. When V
DD
is first connected, the AD7827 is in a low
current mode of operation. In order to carry out a conversion
the AD7827 must first be powered up. T he AD7827 is pow-
ered up by a rising edge on the
CONVST
pin and a conversion
is initiated on the falling edge of
CONVST
. Figure 9 shows
how to power up the AD7827 when V
DD
is first connected or
after the ADC has been powered down using the
CONVST
pin
when using either the on-chip, or an external, reference. When
using an external reference the falling edge of
CONVST
may
occur before the required power-up time has elapsed; however,
the conversion will not be initiated on the falling edge of
CONVST
but rather at the moment when the part has com-
pletely powered up, 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 con-
version, i.e., a falling edge on
CONVST
may not occur before
the required power-up time has elapsed, when V
DD
is first con-
nected or after the AD7827 has been powered down using the
CONVST
pin as shown in Figure 9.
EXTERNAL REFERENCE
ON-CHIP REFERENCE
CONVERSION INITIATED HERE
CONVERSION INITIATED HERE
V
DD
CONVST
V
DD
CONVST
t
POWER-UP
1
m
s
t
POWER-UP
25
m
s
Figure 9. Power-Up Time
POWE R VS. T HROUGHPUT
Superior power performance can be achieved by using the
automatic power-down (Mode 2) at the end of a conversion
(see Operating Modes section of this data sheet).
Figure 10 shows how the automatic power-down is implemented
using the
CONVST
signal to achieve the optimum power per-
formance for the AD7827. T he duration of the
CONVST
pulse
is set to be equal to or less than the power-up time of the de-
vices (see Operating Modes section). As the throughput rate is
reduced, the device remains in its power-down state for longer and
the average power consumption over time drops accordingly.
For example, if the AD7827 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
follows. T he power dissipation during normal operation is
30 mW, V
DD
= 3 V.
CONVST
t
POWER-UP
1
m
s
t
CONVERT
330ns
POWER-DOWN
t
CYCLE
10
m
s @ 100kSPS
Figure 10. Automatic Power-Down
If the power-up time is 1
μ
s and the conversion time is 330 ns
(@ 25
°
C), the AD7827 can be said to dissipate 30 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)
×
(30 mW) = 3.99 mW.
Figure 11 shows the Power vs. T hroughput rate for automatic
full power-down.
THROUGHPUT – kSPS
100
10
0.1
0
500
50
100
150
200
250
300
350
400
450
1
P
Figure 11. Power vs. Throughput
FREQUENCY – Hz
0
–40
–80
0
500
50
d
100
150
200
250
300
350
400
450
–10
–20
–60
–70
–30
–50
2048 POINT FFT
SAMPLING
1MSPS
F
IN
= 30kHz
Figure 12. AD7827 SNR
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AD7827BN | 14-Bit 48KSPS DAS with ADC, MUX, PGA and Internal Reference 28-SSOP -40 to 85 |
| AD7827BR | 3 V/5 V, 1 MSPS, 8-Bit, Serial Interface Sampling ADC |
| AD7828UE | LC2MOS High Speed 4- & 8-Channel 8-Bit ADCs |
| AD7828CQ | LC2MOS High Speed 4- & 8-Channel 8-Bit ADCs |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD7827BN | 制造商:Analog Devices 功能描述:ADC Single Semiflash 1Msps 8-bit Serial 8-Pin PDIP 制造商:Rochester Electronics LLC 功能描述:8-BIT SERIAL 2MSPS ADC - Bulk 制造商:Analog Devices 功能描述:IC 8BIT ADC 7827 DIP8 |
| AD7827BNZ | 制造商:Analog Devices 功能描述:ADC Single Semiflash 1Msps 8-bit Serial 8-Pin PDIP 制造商:Analog Devices 功能描述:IC 8BIT ADC 7827 DIP8 |
| AD7827BR | 制造商:Analog Devices 功能描述:ADC Single Semiflash 1Msps 8-bit Serial 8-Pin SOIC N 制造商:Rochester Electronics LLC 功能描述:8-BIT SERIAL 2MSPS ADC - Bulk |
| AD7827BR-REEL | 制造商:Analog Devices 功能描述:ADC Single Semiflash 1Msps 8-bit Serial 8-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:8-BIT SERIAL 2MSPS ADC - Tape and Reel |
| AD7827BR-REEL7 | 制造商:Analog Devices 功能描述:ADC Single Semiflash 1Msps 8-bit Serial 8-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:8-BIT SERIAL 2MSPS ADC - Tape and Reel |
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