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| 型號： | AD7478ARTZ-REEL |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 6/25頁 |
| 文件大小： | 0K |
| 描述： | IC ADC 8BIT 1MSPS SOT23-6 |
| 產品變化通告： | Product Discontinuance 27/Oct/2011 |
| 標準包裝： | 10,000 |
| 位數(shù)： | 8 |
| 采樣率（每秒）： | 1M |
| 數(shù)據(jù)接口： | DSP，MICROWIRE?，QSPI?，串行，SPI? |
| 轉換器數(shù)目： | 1 |
| 功率耗散（最大）： | 17.5mW |
| 電壓電源： | 單電源 |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | SOT-23-6 |
| 供應商設備封裝： | SOT-23-6 |
| 包裝： | 帶卷 (TR) |
| 輸入數(shù)目和類型： | 1 個單端，單極 |
AD7476/AD7477/AD7478
Rev. F | Page 13 of 24
THEORY OF OPERATION
CIRCUIT INFORMATION
The AD7476/AD7477/AD7478 are, respectively, 12-bit, 10-bit,
and 8-bit, fast, micropower, single-supply ADCs. The parts can
be operated from a 2.35 V to 5.25 V supply. When operated
from either a 5 V supply or a 3 V supply, the AD7476/AD7477/
AD7478 are capable of throughput rates of 1 MSPS when
provided with a 20 MHz clock.
Each AD7476/AD7477/AD7478 provides an on-chip, track-
and-hold ADC and a serial interface housed in a tiny 6-lead
SOT-23 package, which offers considerable space-saving
advantages. The serial clock input accesses data from the part
and provides the clock source for the successive-approximation
ADC. The analog input range is 0 V to VDD. An external
reference is not required for the ADC, nor is there a reference
on-chip. The reference for the AD7476/AD7477/AD7478 is
derived from the power supply and thus provides the widest
dynamic input range.
The AD7476/AD7477/AD7478 also feature a power-down
option to save power between conversions. The power-down
feature is implemented across the standard serial interface as
described in the Modes of Operation section.
CONVERTER OPERATION
The AD7476/AD7477/AD7478 are successive-approximation
analog-to-digital converters based around a charge redistribu-
of the ADC. Figure 10 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 VIN.
0102
4-
0
10
COMPARATOR
SAMPLING
CAPACITOR
ACQUISITION
PHASE
A
B
AGND
SW1
SW2
VIN
VDD/2
CHARGE
REDISTRIBUTION
DAC
CONTROL
LOGIC
Figure 10. ADC Acquisition Phase
When the ADC starts a conversion (see Figure 11), SW2 opens
and SW1 moves to Position B, causing the comparator to
become unbalanced. The control logic and the charge redistri-
bution 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
transfer function.
01
02
4-
01
1
COMPARATOR
SAMPLING
CAPACITOR
CONVERSION
PHASE
A
B
AGND
SW1
SW2
VIN
VDD/2
CHARGE
REDISTRIBUTION
DAC
CONTROL
LOGIC
Figure 11. ADC Conversion Phase
ADC TRANSFER FUNCTION
The output coding of the AD7476/AD7477/AD7478 is straight
binary. For the AD7476/AD7477, designed code transitions
occur midway between successive integer LSB values, such as
LSB, 1 LSB, and so on. The LSB size for the AD7476 is
VDD/4096, and the LSB size for the AD7477 is VDD/1024. The
ideal transfer characteristic for the AD7476/AD7477 is shown
in Figure 12.
For the AD7478, designed code transitions occur midway
between successive integer LSB values, such as 1 LSB, 2 LSB,
and so on. The LSB size for the AD7478 is VDD/256. The ideal
transfer characteristic for the AD7478 is shown in Figure 13.
0
102
4-
01
2
ANALOG INPUT
111 ... 111
0V
0.5LSB
+VDD – 1.5LSB
ADC
CO
DE
111 ... 110
111 ... 000
011 ... 111
000 ... 010
000 ... 001
000 ... 000
1LSB = VDD/4096 (AD7476)
1LSB = VDD/1024 (AD7477)
Figure 12. Transfer Characteristic for the AD7476/AD7477
010
24-
013
ANALOG INPUT
111 ... 111
0V
1LSB
+VDD – 1LSB
ADC
CO
DE
111 ... 110
111 ... 000
011 ... 111
000 ... 010
000 ... 001
000 ... 000
1LSB = VDD/256 (AD7478)
Figure 13. Transfer Characteristic for AD7478
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| AD7478ARTZ-REEL3 | 制造商:AD 制造商全稱:Analog Devices 功能描述:1 MSPS, 12-/10-/8-Bit ADCs in 6-Lead SOT-23 |
| AD7478ARTZ-REEL7 | 功能描述:IC ADC 8BIT 1MSPS SOT23-6 RoHS:是 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 系列:microPOWER™ 位數(shù):8 采樣率（每秒）:1M 數(shù)據(jù)接口:串行，SPI? 轉換器數(shù)目:1 功率耗散（最大）:- 電壓電源:模擬和數(shù)字 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應商設備封裝:24-VQFN 裸露焊盤（4x4） 包裝:Digi-Reel® 輸入數(shù)目和類型:8 個單端，單極 產品目錄頁面:892 (CN2011-ZH PDF) 其它名稱:296-25851-6 |
| AD7478ARTZ-REEL73 | 制造商:AD 制造商全稱:Analog Devices 功能描述:1 MSPS, 12-/10-/8-Bit ADCs in 6-Lead SOT-23 |
| AD7478ARTZ-REEL7-C | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| AD7478AWARMZ | 制造商:Analog Devices 功能描述:ADC Single SAR 1.2Msps 8-bit Serial 8-Pin MSOP T/R 制造商:Analog Devices 功能描述:ADC SGL SAR 1.2MSPS 8BIT SERL 8MSOP - Rail/Tube |
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