AFE
CS1258
MAIN PARAMETERS

Eight-polar and multi-frequency body impedance measurement 

Built-in 24 bit ADC with 19.5 bits effective resolution 

Supports phase angle, respiration rate and heart rate measurement 

3-line SPI interface

Introduction

The CS1258 is an high performance eight-polar measurement AFE chip, which integrates ΣΔ ADC, body impedance measurement module (BIM), and digital filter. The ADC includes MUXP/MUXN with 8 inputs, Level shifting module, programmable low noise gain amplifier (PGA). The BIM module uses a sinusoidal excitation source to convert the body impedance into a voltage signal and send it to the ADC for measurement. It can support multi-electrode and multi-frequency body impedance measurement, phase angle measurement, respiration rate and heart rate measurement.

Features

Input

— Support single end input and differential input

— Built-in voltage level shift module

PGA

— Optional 1/2/4/8/16/32/64/128 gain

— Equivalent input impedance up to 100MΩ

BIM

— Support four-polar measurement

— Support 5K/10K/25K/50K/100K/250KHz multi-frequency measurement

— Support impedance absolute value and phase angle measurements

ADC

— 24 bit resolution

— 8 optional AD rate 10~1280Hz

— 19.5bits effective resolution (Vref =  2.35V, AD Rate = 40Hz, PGA = 128x)

LDO and internal voltage reference

— Built-in output 2.35/2.45/2.8/3.0V optional, accuracy ±1%

— Built-in low drift 2.048V voltage reference, accuracy ±1%

Support different working modes: high performance, normal, low power, sleep

Support different measurement modes: voltage measurement, temperature measurement, BIM measurement and manual measurement, which can be switched with single command

Built-in low drift clock source

3-line SPI interface

Applications

Body impedance analysis

AC body fat measurement

Bridge sensor

Body scales

Pressure measurement

Block Diagram
DOCUMENT
CS1258系列AFE用户手册v02
2018-04-25
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