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參數(shù)資料
| 型號： | AD7944BCPZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 5/28頁 |
| 文件大小： | 0K |
| 描述： | IC ADC 14BIT 2.5MSPS 20LFCSP |
| 標(biāo)準(zhǔn)包裝： | 1 |
| 系列： | PulSAR® |
| 位數(shù)： | 14 |
| 采樣率（每秒）： | 2.5M |
| 數(shù)據(jù)接口： | DSP，MICROWIRE?，QSPI?，串行，SPI? |
| 轉(zhuǎn)換器數(shù)目： | 1 |
| 功率耗散（最大）： | 33mW |
| 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： | 20-VFQFN 裸露焊盤，CSP |
| 供應(yīng)商設(shè)備封裝： | 20-LFCSP-VQ |
| 包裝： | 托盤 |
| 輸入數(shù)目和類型： | 1 個(gè)偽差分，單極 |
| 產(chǎn)品目錄頁面： | 780 (CN2011-ZH PDF) |
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AD7944
Rev. A | Page 13 of 28
THEORY OF OPERATION
COMP
SWITCHES CONTROL
BUSY
OUTPUT CODE
CNV
CONTROL
LOGIC
SW+
LSB
SW–
LSB
IN+
REF
REFGND
IN–
MSB
C
4C
2C
4096C
8192C
C
4C
2C
4096C
8192C
04658-
005
Figure 21. ADC Simplified Schematic
CIRCUIT INFORMATION
The AD7944 is a fast, low power, single-supply, precise, 14-bit
ADC using a successive approximation architecture. The AD7944
features different modes to optimize performance according to the
application. In turbo mode, the AD7944 is capable of converting
2,500,000 samples per second (2.5 MSPS).
The AD7944 provides the user with an on-chip track-and-hold
and does not exhibit any pipeline delay or latency, making it
ideal for multiple multiplexed channel applications.
The AD7944 can be interfaced to any 1.8 V to 2.7 V digital logic
family. It is available in a space-saving 20-lead LFCSP that allows
flexible configurations. It is pin-for-pin compatible with the
CONVERTER OPERATION
The AD7944 is a successive approximation ADC based on a
charge redistribution DAC. Figure 21 shows the simplified
schematic of the ADC. The capacitive DAC consists of two
identical arrays of 14 binary-weighted capacitors that are
connected to the two comparator inputs.
During the acquisition phase, the terminals of the array tied to
the input of the comparator are connected to AGND via SW+
and SW. All independent switches are connected to the analog
inputs. Therefore, the capacitor arrays are used as sampling
capacitors and acquire the analog signal on the IN+ and IN
inputs. When the acquisition phase is completed and the CNV
input goes high, a conversion phase is initiated.
When the conversion phase begins, SW+ and SW are opened
first. The two capacitor arrays are then disconnected from the
analog inputs and connected to the REFGND input. Therefore,
the differential voltage between the IN+ and IN inputs captured
at the end of the acquisition phase is applied to the comparator
inputs, causing the comparator to become unbalanced. By switch-
ing each element of the capacitor array between REFGND and
REF, the comparator input varies by binary-weighted voltage
steps (VREF/2, VREF/4, … VREF/16,384). The control logic toggles
these switches, starting with the MSB, to bring the comparator
back into a balanced condition. After the completion of this
process, the part returns to the acquisition phase, and the control
logic generates the ADC output code and a busy signal indicator.
Because the AD7944 has an on-board conversion clock, the
serial clock, SCK, is not required for the conversion process.
CONVERSION MODES OF OPERATION
The AD7944 features two conversion modes of operation:
turbo and normal. Turbo conversion mode (TURBO high)
allows the fastest conversion rate of up to 2.5 MSPS and does
not power down between conversions. The first conversion in
turbo mode should be ignored because it contains meaningless
data. For applications that require lower power and slightly
slower sampling rates, the normal conversion mode (TURBO
low) allows a maximum conversion rate of 2.0 MSPS and
powers down between conversions. The first conversion in
normal mode contains meaningful data.
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| AD7944BCPZ-RL7 | 功能描述:IC ADC 14B 2.5MSPS PULSR 20LFCSP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:PulSAR® 標(biāo)準(zhǔn)包裝:1,000 系列:- 位數(shù):12 采樣率（每秒）:300k 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:75mW 電壓電源:單電源 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:24-SOIC 包裝:帶卷 (TR) 輸入數(shù)目和類型:1 個(gè)單端，單極；1 個(gè)單端，雙極 |
| AD7945 | 制造商:AD 制造商全稱:Analog Devices 功能描述:+3.3 V/+5 V Multiplying 12-Bit DACs |
| AD7945AN-B | 功能描述:IC DAC 12BIT MULT PARALL 20-DIP RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:2,400 系列:- 設(shè)置時(shí)間:- 位數(shù):18 數(shù)據(jù)接口:串行 轉(zhuǎn)換器數(shù)目:3 電壓電源:模擬和數(shù)字 功率耗散（最大）:- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:36-TFBGA 供應(yīng)商設(shè)備封裝:36-TFBGA 包裝:帶卷 (TR) 輸出數(shù)目和類型:* 采樣率（每秒）:* |
| AD7945ANZ-B | 功能描述:IC DAC 12BIT MULT PARALL 20DIP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:47 系列:- 設(shè)置時(shí)間:2µs 位數(shù):14 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 電壓電源:單電源 功率耗散（最大）:55µW 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:28-SSOP（0.209"，5.30mm 寬） 供應(yīng)商設(shè)備封裝:28-SSOP 包裝:管件 輸出數(shù)目和類型:1 電流，單極；1 電流，雙極 采樣率（每秒）:* |
| AD7945ARS-B | 功能描述:IC DAC 12BIT MULT PARALL 20-SSOP RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:47 系列:- 設(shè)置時(shí)間:2µs 位數(shù):14 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 電壓電源:單電源 功率耗散（最大）:55µW 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:28-SSOP（0.209"，5.30mm 寬） 供應(yīng)商設(shè)備封裝:28-SSOP 包裝:管件 輸出數(shù)目和類型:1 電流，單極；1 電流，雙極 采樣率（每秒）:* |
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