參數(shù)資料
型號(hào)： AD7859BSZ
廠商： Analog Devices Inc
文件頁(yè)數(shù)： 6/28頁(yè)
文件大?。?/td> 0K
描述： IC ADC 12BIT 8CHAN LP 44-MQFP
標(biāo)準(zhǔn)包裝： 1
位數(shù)： 12
采樣率（每秒）： 200k
數(shù)據(jù)接口： 并聯(lián)
轉(zhuǎn)換器數(shù)目： 2
功率耗散（最大）： 30mW
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： 44-QFP
供應(yīng)商設(shè)備封裝： 44-MQFP（10x10）
包裝： 托盤
輸入數(shù)目和類型： 8 個(gè)單端，單極；8 個(gè)單端，雙極；4 個(gè)偽差分，單極；4 個(gè)偽差分，雙極
AD7859/AD7859L
REV. A
–14–
and 1.5 CLKIN periods are allowed for the acquisition time.
With a 1.8 MHz clock, this gives a full cycle time of 10
s,
which equates to a throughput rate of 100 kSPS.
When using the software conversion start for maximum
throughput, the user must ensure the control register write op-
eration extends beyond the falling edge of BUSY. The falling
edge of BUSY resets the CONVST bit to 0 and allows it to be
reprogrammed to 1 to start the next conversion.
TYPICAL CONNECTION DIAGRAM
Figure 8 shows a typical connection diagram for the AD7859/
AD7859L. The AGND and the DGND pins are connected
together at the device for good noise suppression. The first
CONVST
applied after power-up starts a self-calibration
sequence. This is explained in the calibration section of this data
sheet. Note that after power is applied to AVDD and DVDD and
the CONVST signal is applied, the part requires (70 ms + 1/
sample rate) for the internal reference to settle and for the self-
calibration on power-up to be completed.
AVDD DVDD
AIN(+)
AIN(–)
CREF1
CREF2
SLEEP
DB15
DB0
CONVST
AGND
DGND
CLKIN
REFIN/REFOUT
AD7859/
AD7859L
ANALOG
SUPPLY
+3V TO +5V
0.1F
10F
0.1F
0.01F
CONVERSION
START SIGNAL
0.1nF EXTERNAL REF
0.1F INTERNAL REF
CAL
0V TO 2.5V
INPUT
4MHz/1.8MHz
OSCILLATOR
OPTIONAL
EXTERNAL
REFERENCE
CS
RD
WR
W/B
BUSY
DVDD
C/P
AD780/
REF192
Figure 8. Typical Circuit
For applications where power consumption is a major concern,
the power-down options can be exercised by writing to the part
and using the SLEEP pin. See the Power-Down section for more
details on low power applications.
CIRCUIT INFORMATION
The AD7859/AD7859L is a fast, 8-channel, 12-bit, single sup-
ply A/D converter. The part requires an external 4 MHz/1.8
MHz master clock (CLKIN), two CREF capacitors, a CONVST
signal to start conversion and power supply decoupling capaci-
tors. The part provides the user with track/hold, on-chip refer-
ence, calibration features, A/D converter and parallel interface
logic functions on a single chip. The A/D converter section of
the AD7859/AD7859L consists of a conventional successive-ap-
proximation converter based around a capacitor DAC. The
AD7859/AD7859L accepts an analog input range of 0 to +VREF.
VREF can be tied to VDD. The reference input to the part con-
nected via a 150 k
resistor to the internal 2.5 V reference and
to the on-chip buffer.
A major advantage of the AD7859/AD7859L is that a conver-
sion can be initiated in software, as well as by applying a signal
to the CONVST pin. The part is available in a 44-pin PLCC or a
44-pin PQFP package, and this offers the user considerable
spacing saving advantages over alternative solutions. The
AD7859L version typically consumes only 5.5 mW making it
ideal for battery-powered applications.
CONVERTER DETAILS
The master clock for the part is applied to the CLKIN pin.
Conversion is initiated on the AD7859/AD7859L by pulsing the
CONVST
input or by writing to the control register and setting
the CONVST bit to 1. On the rising edge of CONVST (or at
the end of the control register write operation), the on-chip
track/hold goes from track to hold mode. The falling edge of the
CLKIN signal which follows the rising edge of CONVST ini-
tiates the conversion, provided the rising edge of CONVST (or
WR
when converting via the control register) occurs typically at
least 10 ns before this CLKIN edge. The conversion takes 16.5
CLKIN periods from this CLKIN falling edge. If the 10 ns set-
up time is not met, the conversion takes 17.5 CLKIN periods.
The time required by the AD7859/AD7859L to acquire a signal
depends upon the source resistance connected to the AIN(+) in-
put. Please refer to the acquisition time section for more details.
When a conversion is completed, the BUSY output goes low,
and the result of the conversion can be read by accessing the
data through the data bus. To obtain optimum performance
from the part, read or write operations should not occur during
the conversion or less than 200 ns prior to the next CONVST
rising edge. Reading/writing during conversion typically de-
grades the Signal-to-(Noise + Distortion) by less than 0.5 dBs.
The AD7859 can operate at throughput rates of over 200 kSPS
(up to 100 kSPS for the AD7859L).
With the AD7859L, 100 kSPS throughput can be obtained as
follows: the CLKIN and CONVST signals are arranged to give
a conversion time of 16.5 CLKIN periods as described above
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD7859L 制造商:AD 制造商全稱:Analog Devices 功能描述:3 V to 5 V Single Supply, 200 kSPS 8-Channel, 12-Bit Sampling ADCs
AD7859LAS 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 12-bit Parallel 44-Pin MQFP 制造商:Rochester Electronics LLC 功能描述:12-BIT 8 CH.PARALLEL 100 KSPS I.C. - Bulk 制造商:Analog Devices 功能描述:IC 12-BIT ADC
AD7859LAS3 制造商:AD 制造商全稱:Analog Devices 功能描述:3 V to 5 V Single Supply, 200 kSPS8-Channel, 12-Bit Sampling ADCs
AD7859LAS-REEL 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 12-bit Parallel 44-Pin MQFP T/R
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