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參數(shù)資料
| 型號： | AD7823 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 8-Bit ADC in 8-Lead microSOIC/DIP(8位A/D轉(zhuǎn)換器) |
| 中文描述： | 8位ADC的8引腳microSOIC /文憑（8位的A / D轉(zhuǎn)換器） |
| 文件頁數(shù)： | 8/11頁 |
| 文件大小： | 158K |
| 代理商： | AD7823 |
AD7823
–8–
REV. A
POWER-UP TIMES
The AD7823 has a 1
μ
s power-up time. When V
DD
is first
connected, the AD7823 is in a low current mode of operation.
In order to carry out a conversion, the AD7823 must first be
powered up. The ADC is powered up by a rising edge on the
CONVST
pin. A conversion is initiated on the falling edge of
CONVST
. Figure 12 shows how to power up the AD7823 when
V
DD
is first connected or after the AD7823 is powered down
using the
CONVST
pin.
Care must be taken to ensure that the
CONVST
pin of the
AD7823 is logic low when V
DD
is first applied.
CONVST
t
POWER-UP
1
m
s
V
DD
MODE 1 (
CONVST
IDLES HIGH)
CONVST
V
DD
MODE 2 (
CONVST
IDLES LOW)
1μs
t
POWER-UP
m
Figure 12. Power-Up Times
POWER VS. THROUGHPUT RATE
By operating the AD7823 in Mode 2, the average power con-
sumption of the AD7823 decreases at lower throughput rates.
Figure 13 shows how the automatic power-down is imple-
mented using the
CONVST
signal to achieve the optimum
power performance for the AD7823. The AD7823 is operated
in Mode 2. As the throughput rate is reduced, the device re-
mains in its power-down state for longer, and the average power
consumption over time drops accordingly.
t
100
m
s @ 10kSPS
CONVST
t
CONVERT
m
POWER-DOWN
t
POWER-UP
m
Figure 13. Automatic Power-Down
For example, if the AD7823 is operated in a continuous
sampling mode with a throughput rate of 10 kSPS, the power
consumption is calculated as follows. The power dissipation
during normal operation is 10.5 mW, V
DD
= 3 V. If the power-
up time is 1
μ
s and the conversion time is 4.5
μ
s, then the
AD7823 can be said to dissipate 10.5 mW for 5.5
μ
s (worst
case) during each conversion cycle. If the throughput rate is
10 kSPS, the cycle time is 100
μ
s, and the average power
dissipated during each cycle is (5.5/100)
×
(10.5 mW) = 570
μ
W.
Figure 2 shows a graph of Power vs. Throughput.
OPERATING MODES
Mode 1 Operation (High Speed Sampling)
When the AD7823 is used in this mode of operation, the part is
not powered down between conversions. This mode of opera-
tion allows high throughput rates to be achieved. The timing
diagram in Figure 14 shows how this optimum throughput rate
is achieved by bringing the
CONVST
signal high before the end
of the conversion. The AD7823 leaves its tracking mode and
goes into hold on the falling edge of
CONVST
. A conversion is
also initiated at this time and takes 4.5
μ
s to complete. At this
point, the result of the current conversion is latched into the
serial shift register, and the state of the
CONVST
signal is
checked. The
CONVST
signal should be high at the end of the
conversion to prevent the part from powering down.
A
B
t
2
CONVST
D
OUT
t
1
SCLK
CURRENT CONVERSION
RESULT
Figure 14. Mode 1 Operation Timing
The serial port on the AD7823 is enabled on the rising edge of
the
CONVST
signal–see Serial Interface section. As explained
earlier, this rising edge should occur before the end of the
conversion process if the part is not to be powered down. A
serial read can take place at any stage after the rising edge of
CONVST
. If a serial read is initiated before the end of the
current conversion process (i.e., at time “A”), then the result of
the previous conversion is shifted out on the D
OUT
pin. It is
possible to allow the serial read to extend beyond the end of a
conversion. In this case, the new data will not be latched into
the output shift register until the read has finished. If the user
waits until the end of the conversion process, i.e., 4.5
μ
s after
falling edge of
CONVST
(Point “B”), before initiating a read,
the current conversion result is shifted out.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD7823YN | 制造商:Analog Devices 功能描述:ADC Single SAR 200ksps 8-bit Serial 8-Pin PDIP 制造商:Rochester Electronics LLC 功能描述:8-BIT SERIAL SINGLE ADC I.C. - Bulk 制造商:Analog Devices 功能描述:IC 8BIT ADC 7823 DIP8 |
| AD7823YNZ | 制造商:Analog Devices 功能描述:ADC Single SAR 200ksps 8-bit Serial 8-Pin PDIP 制造商:Analog Devices 功能描述:IC 8BIT ADC 7823 DIP8 |
| AD7823YNZ | 制造商:Analog Devices 功能描述:IC 8BIT ADC 7823 DIP8 |
| AD7823YR | 制造商:Analog Devices 功能描述:ADC Single SAR 200ksps 8-bit Serial 8-Pin SOIC N 制造商:Rochester Electronics LLC 功能描述:8-BIT SERIAL SINGLE ADC I.C. - Bulk 制造商:Analog Devices 功能描述:IC 8-BIT ADC |
| AD7823YRM | 制造商:Analog Devices 功能描述:ADC Single SAR 200ksps 8-bit Serial 8-Pin MSOP 制造商:Rochester Electronics LLC 功能描述:8-BIT SERIAL SINGLE ADC I.C. - Bulk 制造商:Analog Devices 功能描述:IC 8-BIT ADC |
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