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实物图:
大多数系统中,需要在性能与低功耗之间进行权衡。本电路设计的重点是考察部分权衡因素,同时在16位、100 kSPS数据采集系统中实现低功耗(8 mW,典型值)和高性能。
本电路使用 AD7988-1低功耗(350 μA) PulSAR®模数转换器(ADC),该器件直接从 ADA4841-1 高性能、低电压、低功耗运算放大器驱动。选择该放大器是因为它具有极佳的动态性能,可采用单电源电压供电且提供轨到轨输出。此外,输入共模电压范围包括负供电轨。
AD7988-1 ADC需要2.4 V至5.1 V间的外部基准电压。本应用中,选择的基准电压是 ADR4525 精密2.5 V基准电压源。
电路原理图:
本电路的核心是 AD7988-1 16位、100 kSPS逐次逼近型ADC,采用VDD单电源供电。它内置一个低功耗、高速、16位采样ADC和一个多功能串行端口接口(SPI)。在CNV上升沿,该器件对IN+与IN-之间的模拟输入电压差进行采样,范围从0 V至REF。基准电压(REF)由外部提供,并且可以独立于电源电压(VDD)。
在为本电路笔记执行的实验中, AD7988-1 评估板与系统演示平台(SDP, EVAL-SDP-CB1Z)接口,ADC SPI兼容串行接口则连接到DSP SPORT接口。ADC SPI接口能够将几个ADC以菊花链形式连结到单三线式总线上。采用独立VIO电源引脚时,它与1.8 V、2.5 V、3 V或5 V逻辑兼容。
AD7988-1 采用10引脚MSOP或10引脚QFN (LFCSP)封装。为方便起见,该电路板采用MSOP封装。
ADC输入从 ADA4841-1单位增益稳定、低噪声和低失真、轨到轨输出放大器进行缓冲和驱动,该器件通常在1.1 mA的静态电流下工作。此放大器提供2.1 nV/√Hz的低宽带电压噪声和1.4 pA/√Hz的电流噪声,100 kHz时具有极佳的−105 dBc无杂散动态范围(SFDR)。为了在更低频率下保持低噪声环境,10 Hz时放大器具有7 nV/√Hz和13 pA/√Hz的低1/f噪声。
使 ADA4841-1非常适合单电源应用的主要特性是,它在该应用中可以采用单供电轨供电,同时将可负供电轨接地。放大器输出摆幅可以达到地电平的50 mV范围内,这是本应用可接受的值。请注意,输入共模电压范围从负供电轨扩展至正供电轨的1 V范围内。为容纳目标信号范围(0 V至2.5 V),必须提供1 V裕量;因此本电路中使用4 V供电轨。
ADA4841-1 采用6引脚SOT-23或8引脚SOIC封装。
本应用中使用的2.5 V基准电压源是 ADR4525 ,属于 ADR45xx 基准电压源系列,可以提供高精度、低功耗、低噪声,且具有±0.01%初始精度、极佳的温度稳定性和低输出噪声。 ADR4525 的低热致输出电压迟滞和低长期输出电压漂移提高了系统性能。700 μA的最大工作电流和500 mV的低压差(最大值)使该器件最适合便携式设备。
用于本电路中的三个产品的额定工作温度范围均为−40°C至+125°C全工业温度范围。
BOM表:
C1 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C2 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C3 | CAP | 10nF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H103KA01D | FEC 1118178 | C4 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C5 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C6 | CAP | 1uF | ±10% | C0805 | Yes | Top | CAPACITOR, 0805, 1UF, 50V, X7R | MURATA | GRM21BR71H105KA12L | FEC 1735541 | C7 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | MURATA | GRM188R71H104KA93D | FEC 8820023 | C8 | CAP | 1uF | ±10% | C0805 | Yes | Top | CAPACITOR, 0805, 1UF, 50V, X7R | MURATA | GRM21BR71H105KA12L | FEC 1735541 | C9 | CAP+ | 10uF | ±10% | RTAJ_B | Yes | Top | 20V Tantalum Capacitor | AVX | TAJB106K020RNJ | FEC 197427 | C10 | CAP+ | 10uF | ±10% | RTAJ_B | Yes | Top | 20V Tantalum Capacitor | AVX | TAJB106K020RNJ | FEC 197427 | C11 | CAP+ | 10uF | ±10% | RTAJ_B | Yes | Top | 20V Tantalum Capacitor | AVX | TAJB106K020RNJ | FEC 197427 | C12 | CAP+ | 10uF | ±10% | RTAJ_B | Yes | Top | 20V Tantalum Capacitor | AVX | TAJB106K020RNJ | FEC 197427 | C13 | CAP | 2.7nF | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, 2700PF, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | FEC 1844178 | C14 | CAP | 10pF | ±5% | C0603 | Yes | Top | CAP CERAMIC 10PF, 100V, C0G, 0603 | AVX | 06031A100JAT2A | FEC 1273324 | C15 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C16 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C17 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C18 | CAP | 1uF | ±10% | C0805 | Yes | Top | CAPACITOR, 0805, 1UF, 50V, X7R | MURATA | GRM21BR71H105KA12L | FEC 1735541 | C19 | CAP+ | 10uF | ±10% | RTAJ_B | Yes | Top | 20V Tantalum Capacitor | AVX | TAJB106K020RNJ | FEC 197427 | C20 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C21 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C22 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C23 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C24 | CAP | 0.1uF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H104KA93D | FEC 8820023 | C25 | CAP+ | 22uF | ±10% | RTAJ_B | Yes | Top | 20V Tantalum Capacitor | AVX | TAJB226K020RNJ | FEC 1135057 | C26 | CAP | DNI |
| C0603 | Yes | Top | n/a | n/a | n/a | Do Not Place | C27 | CAP | DNI |
| C0603 | Yes | Top | n/a | n/a | n/a | Do Not Place | C28 | CAP | DNI |
| C0603 | Yes | Top | n/a | n/a | n/a | Do Not Place | C29 | CAP | DNI |
| C0603 | Yes | Top | n/a | n/a | n/a | Do Not Place | C30 | CAP | DNI |
| C0603 | Yes | Top | n/a | n/a | n/a | Do Not Place | C31 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C32 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C33 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C34 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C35 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C36 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C37 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C38 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C39 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C40 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C41 | CAP | DNI | ±5% | C0603 | Yes | Top | CAPACITOR CERAMIC, TBD, 50V, C0G/NP0, 0603 | TDK | C1608C0G1H272J | Do Not Place | C42 | CAP | 10nF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H103KA01D | FEC 1118178 | C43 | CAP | 150pF | ±5% | C0805 | Yes | Top | CAPACITOR, 0805, 150pF, 50V, COG/NPO | MULTICOMP | MCAA000332 | FEC 1759205 | C44 | CAP | DNI | ±10% | C0805 | Yes | Top | CAPACITOR, 0805, 1UF, 50V, X7R | MURATA | GRM21BR71H105KA12L | Do Not Place | C45 | CAP | 10nF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H103KA01D | FEC 1118178 | C46 | CAP | 10nF | ±10% | C0603 | Yes | Top | 50V X7R Ceramic Capacitor | Murata | GRM188R71H103KA01D | FEC 1118178 | C47 | CAP+ | 10uF | ±10% | RTAJ_B | Yes | Top | 20V Tantalum Capacitor | AVX | TAJB106K020R | FEC 197427 | C48 | CAP | 1uF | ±10% | C0805 | Yes | Top | CAPACITOR, 0805, 1UF, 50V, X7R | MURATA | GRM21BR71H105KA12L | FEC 1735541 | J1 | CON\POWER4 |
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| CON\POWER4 | No | Top | TERMINAL BLOCK, PCB, 4WAY | LUMBERG | KRM 04 | FEC 1177877 | J2 | SDP-STANDARD-CONN |
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| CON-120/FX8-120S-SV_W/S | No | Top | 120-way connector, 0.6mm pitch | Hirose | FX8-120S-SV(21) | FEC 1324660 | J3 | SMB_JACK_RIGHT_ANGLED | N/A | N/A | SMB_JACK_RIGHT_ANGLED | No | Top | CONN SMB JACK R/A PC MNT GOLD | EMERSON | 131-3701-301 | Digikey J472-ND | J4 | SMB_JACK_RIGHT_ANGLED | N/A | N/A | SMB_JACK_RIGHT_ANGLED | No | Top | CONN SMB JACK R/A PC MNT GOLD | EMERSON | 131-3701-301 | Digikey J472-ND | R1 | RES | DNI | 1% | R0603 | Yes | Top | RESISTOR, 0603 TBD | MULTICOMP | MC 0.063W 0603 1% TBD | Do Not Place | R2 | RES | 49r9 | 0.01 | R0805 | Yes | Top | RESISTOR, 0805, 49R9, 0.1%, 0.125W | PANASONIC | ERA6AEB49R9V | FEC 1810372 | R3 | RES | 0r | 0.01 | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 0R | FEC 9331662 | R4 | RES | 49r9 | 0.01 | R0805 | Yes | Top | RESISTOR, 0805, 49R9, 0.1%, 0.125W | PANASONIC | ERA6AEB49R9V | FEC 1810372 | R5 | RES | 10k | 0.01 | R0805 | Yes | Top | THICK FILM CHIP RESISTOR | VISHAY DRALORIC | CRCW080510K0FKEAHP | FEC 1738972 | R6 | RES | 10k | 0.01 | R0805 | Yes | Top | THICK FILM CHIP RESISTOR | VISHAY DRALORIC | CRCW080510K0FKEAHP | FEC 1738972 | R7 | RES | DNI | 1% | R0603 | Yes | Top | RESISTOR, 0603 TBD | Multicomp | MC 0.063W 0603 1% TBD | Do Not Place | R8 | RES | 22R | 0.01 | R0805 | Yes | Top | RESISTOR, 22R 1% 0805 | Vishay Draloric | CRCW080522ROFKEAHP | FEC 1738936 | R9 | RES | 0r | 0.01 | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 0R | FEC 9331662 | R10 | RES | 0r | 0.01 | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 0R | FEC 9331662 | R11 | RES | DNI | 1% | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 0R | Do Not Place | R12 | RES | 60k4 | 0.01 | R0603 | Yes | Top | RESISTOR, 0603 60K4 | MULTICOMP | MC 0.063W 0603 1% 60K4 | FEC 1170965 | R13 | RES | 294k | 0.01 | R0603 | Yes | Top | RESISTOR, 0603 294K | MULTICOMP | MC 0.063W 0603 1% 294K | FEC 1171030 | R14 | RES | 100K | 0.01 | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 1% 100K | FEC 9330402 | R15 | RES | 100K | 0.01 | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 1% 100K | FEC 9330402 | R16 | RES | 0r | 0.01 | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 0R | FEC 9331662 | R17 | RES | 0r | 0.01 | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 0R | FEC 9331662 | R18 | RES | 0r | 0.01 | R0603 | Yes | Top | SMD Resistor | Multicomp | MC 0.063W 0603 0R | FEC 9331662 | R19 | RES | DNI |
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| Yes | Top |
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| Do Not Place | R20 | RES | DNI |
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| Yes | Top |
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| Do Not Place | R21 | RES | DNI |
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| Yes | Top |
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| Do Not Place | R22 | RES | 10k | 0.01 | R0805 | Yes | Top | THICK FILM CHIP RESISTOR | VISHAY DRALORIC | CRCW080510K0FKEAHP | FEC 1738972 | R23 | RES | 10k | 0.01 | R0805 | Yes | Top | THICK FILM CHIP RESISTOR | VISHAY DRALORIC | CRCW080510K0FKEAHP | FEC 1738972 | R24 | RES | 82K | 0.01 | 603 | Yes | Top | RESISTOR, 0603 82K,0.063W,1% | MULTICOMP | MC 0.063W 0603 1% 82K | FEC 9331573 | R25 | RES | DNI |
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| Yes | Top |
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| Do Not Place | R26 | RES | DNI | 1% | R0603 | Yes | Top | RESISTOR, 0603 TBD | MULTICOMP | MC 0.063W 0603 1% TBD | Do Not Place | R27 | RES | DNI | 1% | R0603 | Yes | Top | RESISTOR, 0603 TBD | MULTICOMP | MC 0.063W 0603 1% TBD | Do Not Place | R28 | RES | DNI | 1% | R0603 | Yes | Top | RESISTOR, 0603 TBD | MULTICOMP | MC 0.063W 0603 1% TBD | Do Not Place | R29 | RES | DNI | 1% | R0603 | Yes | Top | RESISTOR, 0603 TBD | MULTICOMP | MC 0.063W 0603 1% TBD | Do Not Place | R30 | RES0603 | 330k | 5% | R0603 | Yes | Top | RESISTOR, 0603 330K | MULTICOMP | MC 0.063W 0603 5% 330K | FEC 9332057 | R31 | RES | 0r | 0.01 | R0603 | Yes | Top | SMD Resistor | MULTICOMP | MC 0.063W 0603 0R | FEC 9331662 | R32 | RES | DNI | 1% | R0603 | Yes | Top | RESISTOR, 0603 TBD | MULTICOMP | MC 0.063W 0603 1% TBD | Do Not Place | R33 | RES | 0r | 0.01 | R0603 | Yes | Top | SMD Resistor | MULTICOMP | MC 0.063W 0603 0R | FEC 9331662 | SL1 | JUMPER2\0603_BRIDGE |
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| 0603-3PIN_BRIDGE | Yes | Top | 2-Way Shorting Option - Use 0r 0603 Resistor in Position "B" | Multicomp | MC 0.063W 0603 0r | FEC 933-1662 | U1 | NC7S08 |
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| SOT23-5 | Yes | Top | Single AND Gate | Fairchild | NC7SZ085M | FEC 1013807 | U2 | 24LC32A-I/MS |
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| MSO8 | Yes | Top | 32K I2C Serial EEPROM, MSOP8 | Microchip | 24LC32A-I/MS | FEC 1331330 | U3 | NC7S08 |
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| SOT23-5 | Yes | Top | Single AND Gate | Fairchild | NC7SZ085M | FEC 1013807 | U4 | NC7S08 |
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| SOT23-5 | Yes | Top | Single AND Gate | Fairchild | NC7SZ085M | FEC 1013807 | U5 | NC7S04 |
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| SOT23-5 | Yes | Top | Single INV | Fairchild | NC7SZ04 | FEC 1013809 | U6 | ADR4525BRZ |
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| SO8NB | Yes | Top |
| Analog Devices | ADR4525BRZ | ADR4525BRZ | U7 | AD8032ARMZ |
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| MSO8 | Yes | Top | 2.7 V, 800 μA, 80 MHz Rail-to-Rail I/O Dual Amplifier | Analog Devices | AD8032ARMZ | AD8032ARMZ | U8 |
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| Yes | Top |
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| Do Not Place | U9 | DNI (solder short needed between pads 1 and 8) |
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| Yes | Top |
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| DNI (solder short needed between pads 1 and 8) | U10 | AD7988-1BRMZ |
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| MSO10 | Yes | Top | 16-Bit, 1 MSPS PulSAR® ADC in MSOP | Analog Devices | AD7988-1BRMZ | AD7988-1BRMZ | U11 |
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| Yes | Top |
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| Do Not Place | U12 | ADA4841-1YRZ-R7 |
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| SO8NB | Yes | Top | Low Noise, High Speed Amplifier for 16-Bit Systems | Analog Devices | ADA4841-1YRZ-R7 | ADA4841-1YRZ-R7 | Screw1 |
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| SCREW, CHEESE, NYLON, M3X10, PK100 | ALLTHREAD | 119030010 | FEC 7070597 | Screw2 |
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| SCREW, CHEESE, NYLON, M3X10, PK100 | ALLTHREAD | 119030010 | FEC 7070597 | Nut1 |
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| NUT/WASHER, NYLON, M3, PK100 | DURATOOL | 1140030 | FEC 7061857 | Nut2 |
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| NUT/WASHER, NYLON, M3, PK100 | DURATOOL | 1140030 | FEC 7061857 |
全部资料(压缩包)下载:
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