TI公司的LMP92064是一款具有SPI接口的高精度低端数据电流、电压监测模拟前端芯片，该芯片通过内部精确电流传感器运放测量通过负载的分流器电阻电流量，并通过缓冲电压通道测量负载电压源。电流、电压采样为12位ADC采样，速率为同步125ksps，内部集成2.048V的ADC参考电压，在单向传感器计量中可以获得非常高精度的功率计算结果。本文首先介绍芯片的简介、特性、内部框图及应用领域，并给出相应设计方案的设计原理图、元器件列表及PCB元件布局图。

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应用：

Enterprise Servers
Telecommunications
Power Management

 
图1. LMP92064内部方框图

LMP92064方案原理图：

图2. LMP92064方案原理图

LMP92064方案材料清单：


PCB元件布局图：