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TI AFE4110精度0.1度C数字温度计解决方案

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TI公司的AFE4110是基于超低功耗MSP430 RISC处理器,配置有两个16位计时器,48段LCD驱动器,可编程模拟池,电源监视器和基准电压源,特别适合采用单颗SR60电池的低成本数字温度计,工作电压1.1V-1.55V,3mA 1.85V内部电荷泵用于外接EEPROM和内部LCD驱动器,工作时功耗45µA/MHz (1.55V),深度睡眠功耗小于0.4µA,主要用于数字温度计,计步器,温度调节器和其它手持设备.本文介绍了AFE4110主要特性,功能框图,AFE4110温度计演示板主要特性,电路图,材料清单和PCB元件布局图.

The Texas Instruments MSP430 family of low-power mixed signal ASSPs consists of many devices featuring different sets of peripherals targeted for various consumer medical applications. The AFE4110 CPU architecture is based on the popular ultra low power Texas Instruments MSP430 RISC processor.

The AFE4110 configuration with two 16-bit timers, integrated 48-segment LCD driver, programmable Analog Pool, supply voltage monitor and internal reference voltage source is particularly well suited for implementation of low cost digital thermometers operating from a single cell SR60 battery. The capability to correct the on chip high frequency oscillator output facilitates the generation and measurement of real time intervals. For many applications, this capability allows system designers to eliminate a clock crystal from the system BOM.

AFE4110主要特性:

Ultra Low Supply-Voltage (ULV) Range

1.1V - 1.55V Unregulated Single Cell Battery Operation(CPU, System Core, and Timers)3mA 1.85V Internal Charge Pump for External EEPROM (R/W),VDDIO, and Internal LCD Controller

60µA 3.3V Regulated Charge Pump for LCD Drive Pads

Low Power Consumption

Active Mode (AM): 45µA/MHz (1.55V)

Standby Mode (LPM3, LCD): < 25µA

Deep Sleep Mode (LPM5):<0.4µA

8-Bytes Battery Backed RAM for Calibration Retention

Wakeup From Periodic Timer or External Interrupt

Wake-Up from LPM5 in 10ms, Wake-Up from LPM4 in 5µs

16-Bit RISC Architecture

Extended Instructions

125ns Instruction Cycle Time

Compact Clock System

Internal Trimmable High Frequency Clock Oscillator with

Discrete Frequency Selections Between 1MHz and 5.4MHz

20kHz Internal low Frequency Clock Oscillator

External Clock Input (Upto 8MHz)

32kHz Crystal Oscillator

Internal High Frequency Oscillator Frequency Correction

Facilitates Generation and Measurement of Real Time

Intervals Without a Clock Crystal

Utilizes Factory Calibration (E-Fuse), S/W, and a

Single External 1Mύ Resistor

Integrated LCD Controller

Drives 4-Mux, 3-Mux, 2-Mux, or Static Mode LCDs

Up to 48 (4x12) LCD Segments

Two 16-Bit Timer0_A3 with Three Capture/Compare Registers

Extended Input Multiplexer for High Accuracy RC

Discharge Measurement

ULV Analog Pool

8-Bit Analog-to-Digital Converter (ADC)

8-Bit Digital-to-Analog Converter (DAC)

Programmable Comparator (COMP)

Supply-Voltage-Monitoring (SVM)

Internal Temperature Sensor

Internal Voltage Reference

1V Regulated (LDO) Outputs

32-Bit Watch-Dog-Timer (WDT-A)

21-Configurable Analog I/O or Digital GPIO Pads,

2-Power GPIO for 10mA VDD/1.85/3.6V Buzzer Load

10-GPIO for VDDIO Operation with VDD/1.85/

3.6V Internal Level Shifting

11-GPIO for VDD Operation (1.1V – 1.55V)

4-Regulated 1V (LDO) Analog Outputs

1-250mV DAC Analog Output

6-Analog Comparator/ADC Inputs

SPI EEPROM Bootstrap Loader (AFE4110A)

Full Four Wire JTAG Debug Interface

AFE4110应用:

• For any application requiring a full analog LCDs signal chain and an LCD display driver such as digital thermometers, pedometers, thermostats, and other portable single alkaline battery devices.

图1.AFE4110功能方框图

AFE4110温度计演示板

This user’s guide provides a general description of the AFE4110 thermometer demonstration board (demo-pen). Use this document with the AFE4110 data sheet to get a broader understanding of the functions and applications of this device.

The board demonstrates an accurate, low-cost, single-chip temperature measurement solution based on the AFE4110. This device is a general-purpose, low-cost, 1.5-V microcontroller optimized for this application with features like an internal 1.85-V/3.3-V charge-pump for LCD/GPIO interface, buzzer driver, low-power sleep mode, etc.

The measurement is done using an external thermistor with a negative temperature coefficient (NTC) characteristic (resistance decreases with increasing temperature). The thermistor response has been calibrated using two temperature points (at 31°C and 43°C), for an overall typical accuracy of ± 0.1°C over that range, when measured in a calibration bath.