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ADI公司的AD5780是真正18位線性低噪音精密的±10 V DC電壓源,工作電壓雙極電壓高達33V,采用正基準輸入電壓從5V到VDD-2.5V,而負基準輸入電壓從VSS+2.5V到0V,輸出噪音8 nV/√Hz,長期穩定性為0.025 LSB,增益誤差±0.018 ppm/℃,輸出電壓設定時間2.5 μs, 施密特觸發器數字接口35MHz,1.8V兼容數字接口,主要用在醫療儀器,測試測量,工業控制,數據采集系統,數字增益和失調調整,電源控制等.本文介紹了AD57801產品亮點和主要特性, 功能框圖和典型工作電路圖以及評估板EVAL-AD5780主要特性,電路圖,材料清單和PCB布局圖. The AD57801 is a true 18-bit, unbuffered voltage output DAC that operates from a bipolar supply of up to 33 V. The AD5780 accepts a positive reference input range of 5 V to VDD − 2.5 V and a negative reference input range of VSS + 2.5 V to 0 V. Both reference inputs are buffered on chip and external buffers are not required. The AD5780 offers a relative accuracy specifica-tion of ±1 LSB maximum range, and operation is guaranteed monotonic with a ±1 LSB DNL maximum range specification. The part uses a versatile 3-wire serial interface that operates at clock rates of up to 35 MHz and is compatible with standard SPI, QSPI™, MICROWIRE™, and DSP interface standards. The part incorporates a power-on reset circuit that ensures that the DAC output powers up to 0 V in a known output impedance state and remains in this state until a valid write to the device takes place. The part provides an output clamp feature that places the output in a defined load state. AD57801產品亮點: True 18-bit accuracy. Wide power supply range of up to ±16.5 V. −40℃ to +125℃ operating temperature range. Low 8 nV/√Hz noise. Low ±0.018 ppm/℃ gain error temperature coefficient AD57801主要特性: True 18-bit voltage output DAC, ±1 LSB INL 8 nV/√Hz output noise spectral density 0.025 LSB long-term linearity error stability ±0.018 ppm/°C gain error temperature coefficient 2.5 μs output voltage settling time 3.5 nV-sec midscale glitch impulse Integrated precision reference buffers Operating temperature range: −40℃ to +125℃ 4 mm × 5 mm LFCSP package Wide power supply range of up to ±16.5 V 35 MHz Schmitt triggered digital interface 1.8 V-compatible digital interface AD57801應用: Medical instrumentation Test and measurement Industrial control Scientific and aerospace instrumentation Data acquisition systems Digital gain and offset adjustment Power supply control 
圖1.AD57801功能框圖
圖2.AD57801典型工作電路圖 AD57801評估板EVAL-AD5780 Evaluation Board for a 18-Bit Serial Input, Voltage Output DAC with Integrated Precision Reference Buffer Amplifiers The EVAL-AD5780 is a full-featured evaluation board, designed to allow the user to easily evaluate all features of the AD5780 voltage output, 18-bit digital-to-analog converter (DAC). The AD5780 pins are accessible at on-board connectors for external connection. The board can be controlled by two means: via the on-board connector (J3), or via the system development platform connector (J4). The SDP board allows the evaluation board to be controlled through the USB port of a Windows® XP- (SP2 or later) or Vista-based (32-bit) PC using the AD5780 evaluation software. 評估板EVAL-AD5780主要特性: Full-featured evaluation board for the AD5780 Link options PC control in conjunction with Analog Devices, Inc., system development platform PC software for control
圖3.評估板EVAL-AD5780框圖
圖4.評估板EVAL-AD5780電路圖:AD5780
圖5.評估板EVAL-AD5780電路圖:電壓參考電路
圖6.評估板EVAL-AD5780電路圖:SDP板連接器
圖7. 18位精度±10V電壓源簡化電路圖 評估板EVAL-AD5780材料清單:
圖8.評估板EVAL-AD5780 PCB布局圖 詳情請見: 
AD5780[2].pdf
(600.82 KB)
UG-256[2].pdf
(819.83 KB)
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