TI公司的LMP92064是一款具有SPI接口的高精度低端數據電流、電壓監測模擬前端芯片，該芯片通過內部精確電流傳感器運放測量通過負載的分流器電阻電流量，并通過緩沖電壓通道測量負載電壓源。電流、電壓采樣為12位ADC采樣，速率為同步125ksps，內部集成2.048V的ADC參考電壓，在單向傳感器計量中可以獲得非常高精度的功率計算結果。本文首先介紹芯片的簡介、特性、內部框圖及應用領域，并給出相應設計方案的設計原理圖、元器件列表及PCB元件布局圖。
The LMP92064 is a precision low-side digital current sensor and voltage monitor with a digital SPI interface. This analog front-end (AFE) includes a precision current sense amplifier to measure a load current across a shunt resistor and a buffered voltage channel to measure the voltage supply of the load. The current and voltage channels are sampled simultaneously by independent 125 kSps 12-bit ADC converters, allowing for very accurate power calculations in unidirectional sensing applications.
The LMP92064 includes an internal 2.048V reference for the ADCs, eliminating the need of an external reference and reducing component count and board space.
A host can communicate with the LMP92064 using a four-wire SPI interface running at speeds of up to 20 MHz. The fast SPI interface allows the user to take advantage of the higher bandwidth ADC to capture fast varying signals. The four-wire interface with dedicated unidirectional input and output lines also allows for an easy interface to digital isolators in applications where isolation is required.
The LMP92064 operates from a single 4.5V to 5.5V supply and includes a separate digital supply pin. The LMP92064 is specified over a temperature range of –40°C to 105°C, and is available in a 5mm x 4mm WSON-16 package.
LMP92064主要特性：
Two Simultaneous Sampling 12-bit ADCs
Conversion Rate: 125 kSps (Min)
12-bit Current Sense Channel
Input-referred Offset: ±15 µV
Common-mode Voltage Range: –0.2V to 2V
Maximum Differential Input Voltage: +75 mV
Fixed Gain: 25 V/V
Gain Error: ±0.75 % (Max)
Bandwidth (–3dB): 70 kHz
DC PSRR: 100 dB
DC CMRR: 110 dB
12-bit Voltage Channel
INL: ±1LSB
Offset Error: ±2 mV (Max)
Gain Error: ±0.75% (Max)
Maximum Input Voltage: +2.048V
Bandwidth: 100 kHz
Internal Reference
SPI Frequency: Up to 20 MHz
Temperature Range: –40℃ to +105℃
WSON-16 Package
LMP92064應用：
Enterprise Servers
Telecommunications
Power Management
圖1. LMP92064內部方框圖
LMP92064方案原理圖：
圖2. LMP92064方案原理圖
LMP92064方案材料清單：
PCB元件布局圖：
