參數(shù)資料
型號(hào)： AD7812
廠商： Analog Devices, Inc.
英文描述： 350 kSPS, 10-Bit 4-/8-Channel Sampling ADCs(350kSPS八通道采樣A/D轉(zhuǎn)換器)
中文描述： 350 kSPS的，10位4-/8-Channel采樣ADC（350kSPS八通道采樣的A / D轉(zhuǎn)換器）
文件頁(yè)數(shù)： 10/20頁(yè)
文件大小： 215K
代理商： AD7812
AD7811/AD7812
–10–
REV. A
CIRCUIT DESCRIPTION
Converter Operation
The AD7811 and AD7812 are successive approximation analog-
to-digital converters based around a charge redistribution DAC.
The ADCs can convert analog input signals in the range 0 V to
V
DD
. Figures 2 and 3 show simplified schematics of the ADC.
Figure 2 shows the ADC during its acquisition phase. SW2 is
closed and SW1 is in position A, the comparator is held in a
balanced condition and the sampling capacitor acquires the
signal on V
IN
.
V
IN
V
DD
/3
COMPARATOR
CONTROL
LOGIC
CLOCK
OSC
ACQUISITION
PHASE
SW1
A
B
SW2
AGND
SAMPLING
CAPACITOR
CHARGE
REDISTRIBUTION
DAC
Figure 2. ADC Acquisition Phase
When the ADC starts a conversion, see Figure 3, SW2 will
open and SW1 will move to position B causing the comparator
to become unbalanced. The Control Logic and the Charge
Redistribution DAC are used to add and subtract fixed amounts
of charge from the sampling capacitor to bring the comparator
back into a balanced condition. When the comparator is rebal-
anced, the conversion is complete. The Control Logic generates
the ADC output code. Figure 10 shows the ADC transfer
function.
V
IN
V
DD
/3
COMPARATOR
CONTROL
LOGIC
CLOCK
OSC
CONVERSION
PHASE
SW1
A
B
SW2
SAMPLING
CAPACITOR
AGND
CHARGE
REDISTRIBUTION
DAC
Figure 3. ADC Conversion Phase
TYPICAL CONNECTION DIAGRAM
Figure 4 shows a typical connection diagram for the AD7811/
AD7812. The AGND and DGND are connected together at
the device for good noise suppression. The serial interface is
implemented using three wires with RFS/TFS connected to
CONVST
see Serial Interface section for more details. V
REF
is
connected to a well decoupled V
DD
pin to provide an analog
input range of 0 V to V
DD
. If the AD7811 or AD7812 is not
sharing a serial bus with another AD7811 or AD7812 then A0
(package address pin) should be hardwired low. The default
power up value of the package address bit in the control register
is 0. For applications where power consumption is of concern,
the automatic power down at the end of a conversion should be
used to improve power performance. See Power-Down Options
section of the data sheet.
SUPPLY
+2.7V TO +5.5V
10
m
F
μC/μP
THREE-WIRE
SERIAL
INTERFACE
10nF
V
REF
DIN
SCLK
CONVST
V
DD
C
REF
V
IN1
AGND
TFS
RFS
DOUT
A0
DGND
0.1
m
F
V
IN2
V
IN4(8)
AD7811/
AD7812
0V TO
V
REF
INPUT
Figure 4. Typical Connection Diagram
Analog Input
Figure 5 shows an equivalent circuit of the analog input struc-
ture of the AD7811 and AD7812. The two diodes D1 and D2
provide ESD protection for the analog inputs. Care must be
taken to ensure that the analog input signal never exceeds the
supply rails by more than 200 mV. This will cause these diodes
to become forward biased and start conducting current into
the substrate. 20 mA is the maximum current these diodes can
conduct without causing irreversible damage to the part. How-
ever, it is worth noting that a small amount of current (1 mA)
being conducted into the substrate due to an overvoltage on an
unselected channel can cause inaccurate conversions on a se-
lected channel. The capacitor C2 in Figure 5 is typically about
4 pF and can primarily be attributed to pin capacitance. The
resistor R1 is a lumped component made up of the on resistance
of a multiplexer and a switch. This resistor is typically about
125
. The capacitor C1 is the ADC sampling capacitor and
has a capacitance of 3.5 pF.
CONVERSION PHASE – SWITCH OPEN
TRACK PHASE – SWITCH CLOSED
V
IN
D1
D2
V
DD
/3
C1
3.5pF
R1
125
V
C2
4pF
V
DD
Figure 5. Equivalent Analog Input Circuit
The analog inputs on the AD7811 and AD7812 can be config-
ured as single ended with respect to analog ground (AGND),
as pseudo differential with respect to a common, and also as
pseudo differential pairs—see Control Register section.
相關(guān)PDF資料
PDF描述
AD7813 8-/10-Bit Sampling ADC(400kSPS,8位/10位采樣A/D轉(zhuǎn)換器)
AD7814ARM 10-Bit Digital Temperature Sensor in 6-Lead SOT-23
AD7814ART 10-Bit Digital Temperature Sensor in 6-Lead SOT-23
AD7814 10-Bit Digital Temperature Sensor in 6-Lead SOT-23(10位數(shù)字溫度傳感器)
AD7816 10-Bit ADCs with On-Chip Temperature Sensor(10位A/D轉(zhuǎn)換器)
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD7812WYRUZ 功能描述:IC ADC 10BIT 8-CHAN SRL 20TSSOP RoHS:是 類(lèi)別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)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(zhuǎn)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(lèi)型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:28-SOIC W 包裝:帶卷 (TR) 輸入數(shù)目和類(lèi)型:2 個(gè)單端，單極
AD7812WYRUZ-RL 制造商:Analog Devices 功能描述:8 CH. 10-BIT Aanalog-Digital Converter
AD7812YN 制造商:Analog Devices 功能描述:ADC Single SAR 350ksps 10-bit Serial 20-Pin PDIP N 制造商:Rochester Electronics LLC 功能描述:8 CH. 10-BIT ADC I.C. - Bulk 制造商:Analog Devices 功能描述:IC 10BIT ADC 8CH 7812 DIP20
AD7812YNZ 功能描述:IC ADC 10BIT 8CHAN SRL 20DIP RoHS:是 類(lèi)別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 其它有關(guān)文件:TSA1204 View All Specifications 標(biāo)準(zhǔn)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(zhuǎn)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(lèi)型:表面貼裝 封裝/外殼:48-TQFP 供應(yīng)商設(shè)備封裝:48-TQFP（7x7） 包裝:Digi-Reel® 輸入數(shù)目和類(lèi)型:4 個(gè)單端，單極；2 個(gè)差分，單極 產(chǎn)品目錄頁(yè)面:1156 (CN2011-ZH PDF) 其它名稱(chēng):497-5435-6
AD7812YR 功能描述:IC ADC 10BIT 8-CHAN SRL 20-SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 位數(shù):12 采樣率（每秒）:3M 數(shù)據(jù)接口:- 轉(zhuǎn)換器數(shù)目:- 功率耗散（最大）:- 電壓電源:- 工作溫度:- 安裝類(lèi)型:表面貼裝 封裝/外殼:SOT-23-6 供應(yīng)商設(shè)備封裝:SOT-23-6 包裝:帶卷 (TR) 輸入數(shù)目和類(lèi)型:-
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*