MAX86140/86141集成光学传感器：超低功耗脉搏血氧与心率检测解决方案

需积分: 9 161 浏览量更新于2024-07-09 收藏 1.43MB PDF 举报

Maxiam MAX86140/86141是一款专为可穿戴健康监测设备设计的高性能光学脉搏血氧仪和心率传感器数据手册。该系列芯片是集成度极高、功耗极低的光学数据采集系统，其创新之处在于以下几个关键特性： 1. 发射器设计：MAX86140/MAX86141内置三个可编程高电流LED驱动器，每个驱动器能通过外部3x2:1多路复用器控制多达六个LED。如果两个设备以主从模式工作，可以扩展到支持十二个LED，提供灵活的光源控制。 2. 接收器设计：MAX86140配备一个光学读出通道，而MAX86141则具备两个独立通道，可同时工作，提高了数据采集效率。这些设备的信号处理部分非常强大，包括一个19位的低噪声模拟前端（AFE）和业界领先的环境光抑制（ALC）电路，能够有效减少背景光干扰。 3. 信号检测与保护：MAX86140/MAX86141还具有检票式检测和替换功能，确保了在异常条件下数据的准确性和设备稳定性。 4. 电源管理：这些设备仅需1.8V的主电源电压，并且支持3.1V至5.5V的LED驱动电压范围，使得它们在电池供电的可穿戴设备中特别节能。 5. 应用场景广泛：由于其低功耗、紧凑尺寸、易用性和卓越的环境光抑制能力，MAX86140/MAX86141非常适合各种光学传感应用，如脉搏氧饱和度测量和心率监测，特别适合于现代智能手环、智能手表等健康追踪设备。 Maxiam MAX86140/86141数据手册提供了全面的技术细节，强调了其在低功耗和高性能光学传感方面的优势，对于开发高效、精确的可穿戴健康监测设备至关重要。对于任何从事相关领域研发的工程师来说，这份手册是理解和设计这类设备不可或缺的参考资料。

Detailed Description

The MAX86140/MAX86141 are complete integrated opti-

cal data acquisition systems, ideal for optical pulse

oximetry and heart rate detection applications. Both parts

have been designed for the demanding requirements of

mobile and wearable devices and require minimal external

hardware components are necessary for integration into

a wearable device. They include high-resolution, optical

readout signal processing channels with robust ambient

light cancellation and high-current LED driver DACs to

form a complete optical readout signal chain.

The MAX86140/MAX86141 are fully adjustable through

software registers and the digital output data is stored

in a 128-word FIFO within the IC. The FIFO allows the

MAX86140/MAX86141 to be connected to a microcontroller

or processor on a shared bus, where the data is not being

read continuously from the MAX86140/MAX86141’s

registers. Both operate in fully autonomous modes for low

power battery applications.

The MAX86140 consists of a single optical readout channel,

while the MAX86141 incorporates dual optical readout

channels that operate simultaneously. Both parts have

three LED drivers and are well suited for a wide variety of

optical sensing applications.

The MAX86140/MAX86141 operate on a 1.8V main

supply voltage, with a separate 3.1V to 5.5V LED driver

power supply. Both devices have flexible timing and shut-

down configurations as well as control of individual blocks

so an optimized measurement can be made at minimum

power levels.

Optical Subsystem

The optical subsystem in the MAX86140/MAX86141 is

composed of ambient light cancellation (ALC), a continu-

ous-time sigma-delta ADC, and proprietary discrete time

filter. ALC incorporates a proprietary scheme to cancel

ambient light generated photodiode current, allowing

the sensor to work in high ambient light conditions. The

optical ADC has programmable full-scale ranges of 4μA

to 32μA. The internal ADC is a continuous time overs-

ampling sigma delta converter with 19-bit resolution.

The ADC output data rate can be programmed from

8sps (samples per second) to 4096sps per channel. The

MAX86140/MAX86141 includes a proprietary discrete

time filter to reject 50Hz/60Hz interference and changing

residual ambient light from the sensor measurements.

The MAX86140/MAX86141 supports Dynamic Power

Down mode (Low-Power mode) in which the power

consumption is decreased between samples. This mode

is only supported for sample rates 128sps and below. For

more details on the power consumption at each sample

rates, refer to the Electrical Characteristics table.

LED Driver

The MAX86140/MAX86141 integrates three precision LED

driver-current DACs that modulate LED pulses for a

variety of optical measurements. The LED current DACs

have 8-bits of dynamic range with four programmable

full-scale ranges of 31mA, 62mA, 94mA, and 124mA. The

LED drivers are low dropout current sources, allowing for

low-noise, power-supply independent LED currents to be

sourced at the lowest supply voltage possible; therefore

minimizing LED power consumption. The LED pulse width

can be programmed from 14.8μs to 117.3μs to allow the

algorithms to optimize SpO

and HR accuracy at the lowest

dynamic power consumption dictated by the application.

FIFO Conguration

The FIFO is 128 sample depth and is designed to support

various data types, as shown in Table 2. Each sample

width is 3 bytes, which includes a 5-bit tag width. The

tag embedded in the FIFO_DATA is used to identify the

source of each sample data. The description of each Tag

is as shown in Table 3.

LED Sequence Control (address 0x20 ~ 0x22)

The data format in the FIFO, as well as the sequencing of

exposures, are controlled by the LED Sequence Registers

through LEDC1 through LEDC6. There are six LED

Sequence Data Items available, as shown in Table 1. The

exposure sequence cycles through the LED Sequence

bit fields, starting from LEDC1 to LEDC6. The first LED

Sequence field set to NONE (0000) ends the sequence.

www.maximintegrated.com

Maxim Integrated

│

MAX86140/

MAX86141

Best-in-Class Optical Pulse Oximeter and

Heart-Rate Sensor for Wearable Health

There are seven registers that control how the FIFO is configured and read out. These registers are illustrated below.

Write Pointer (Register 0x04)

FIFO_WR_PTR[6:0] points to the FIFO location where the next item will be written. This pointer advances for each item

pushed on to the FIFO by the internal conversion process. The write pointer is a 7-bit counter and will wrap around to

count 0x00 on the next item after count 0x7F.

Read Pointer (Register 0x05)

FIFO_RD_PTR[6:0] points to the location from where the next item from the FIFO will be read via the serial interface.

This advances each time an item is read from the FIFO. The read pointer can be both read and written to. This allows an

item to be reread from the FIFO if it has not already been overwritten. The read pointer is updated from a 7-bit counter

and will wrap around to count 0x00 from count 0x7F.

Overflow Counter (Register 0x06)

OVF_COUNTER[6:0] logs the number of items lost if the FIFO is not read in a timely fashion. This counter holds/

saturates at count value 0x7F. When a complete item is popped from the FIFO (when the read pointer advances), the

OVF_COUNTER is reset to zero. This counter is essentially a debug tool. It should be read immediately before reading

the FIFO in order to check if an overflow condition has occurred.

FIFO Data Counter (Register 0x07)

FIFO_DATA_COUNT[7:0] is a read-only register which holds the number of items available in the FIFO for the host to read.

This increments when a new item is pushed to the FIFO, and decrements when the host reads an item from the FIFO.

FIFO Data (Register 0x08)

FIFO_DATA[7:0] is a read-only register used to retrieve data from the FIFO. It is important to burst read the item from the

FIFO. Each item is three bytes. So burst reading three bytes at FIFO_DATA register via the serial interface advances the

FIFO_RD_PTR. The format and data type of the data stored in the FIFO is determined by the Tag associated with data.

Readout from the FIFO follows a progression defined by LED Sequence Control registers as well. This configuration is

best illustrated by a few examples.

Assume it is desired to perform a SpO

measurement and also monitor the ambient level on the photodiode to adjust the

IR and red LED intensity. To perform this measurement, configure the following registers:

Table 4. PPG Configuration

AD-

DRESS

NAME

B7 B6 B5 B4 B3 B2 B1 B0

0x04 FIFO Write Pointer – FIFO_WR_PTR[6:0]

0x05 FIFO Read Pointer – FIFO_RD_PTR[6:0]

0x06 Overow Counter – OVF_COUNTER[6:0]

0x07

FIFO Data

Counter

FIFO_DATA_COUNT[7:0]

0x08

FIFO Data

FIFO_DATA[7:0]

0x09

FIFO

Conguration 1

– FIFO_A_FULL[6:0]

0x0A

FIFO

Conguration 2

– –

TIME_

STAMP_EN

FLUSH_

FIFO

FIFO_

STAT_CLR

A_FULL_

TYPE

FIFO_RO –

www.maximintegrated.com

Maxim Integrated

│

MAX86140/

MAX86141

Best-in-Class Optical Pulse Oximeter and

Heart-Rate Sensor for Wearable Health

剩余89页未读，继续阅读

weixin_38549327

粉丝: 4
资源: 931

MAX86140/86141集成光学传感器：超低功耗脉搏血氧与心率检测解决方案

Maxiam_MAX32664 数据手册-综合文档

Max32664：超低功耗生物识别传感器中枢

MAX30101：一体化心率和血氧监测传感器模块

MAX32664用户指南：低功耗微控制器在传感器中枢应用

【大厂面试专栏】一份Java程序员需要的技术指南，这里有面试题、系统架构

flashocc-QAT-PTQ.zip

大连理工大学城市学院在四川2020-2024各专业最低录取分数及位次表.pdf

川北医学院在四川2020-2024各专业最低录取分数及位次表.pdf

黑河学院在四川2020-2024各专业最低录取分数及位次表.pdf

西安邮电大学在四川2020-2024各专业最低录取分数及位次表.pdf

最新资源