温度芯片DS18B20+资源-CSDN文库

需积分: 3 178 浏览量 2010-05-23 22:04:19 上传评论收藏 219KB PDF 举报

资源详情

资源评论

资源推荐

1 of 22 REV: 042208

FEATURES

 Unique 1-Wire

Interface Requires Only One

Port Pin for Communication

 Each Device has a Unique 64-Bit Serial Code

Stored in an On-Board ROM

 Multidrop Capability Simplifies Distributed

Temperature-Sensing Applications

 Requires No External Components

 Can Be Powered from Data Line; Power Supply

Range is 3.0V to 5.5V

 Measures Temperatures from -55°C to +125°C

(-67°F to +257°F)

 ±0.5°C Accuracy from -10°C to +85°C

 Thermometer Resolution is User Selectable

from 9 to 12 Bits

 Converts Temperature to 12-Bit Digital Word in

750ms (Max)

 User-Definable Nonvolatile (NV) Alarm

Settings

 Alarm Search Command Identifies and

Addresses Devices Whose Temperature is

Outside Programmed Limits (Temperature

Alarm Condition)

 Available in 8-Pin SO (150 mils), 8-Pin μSOP,

and 3-Pin TO-92 Packages

 Software Compatible with the DS1822

 Applications Include Thermostatic Controls,

Industrial Systems, Consumer Products,

Thermometers, or Any Thermally Sensitive

System

PIN CONFIGURATIONS

DESCRIPTION

The DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an

alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20

communicates over a 1-Wire bus that by definition requires only one data line (and ground) for

communication with a central microprocessor. It has an operating temperature range of -55°C to +125°C

and is accurate to ±0.5°C over the range of -10°C to +85°C. In addition, the DS18B20 can derive power

directly from the data line (“parasite power”), eliminating the need for an external power supply.

Each DS18B20 has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same

1-Wire bus. Thus, it is simple to use one microprocessor to control many DS18B20s distributed over a

large area. Applications that can benefit from this feature include HVAC environmental controls,

temperature monitoring systems inside buildings, equipment, or machinery, and process monitoring and

control systems.

DS18B20

Programmable Resolution

1-Wire Digital Thermomete

www.maxim

ic.com

1-Wire is a registered trademark of Maxim Integrated Products, Inc.

TO-92

(DS18B20)

(

BOTTOM VIEW

)

2 3

DALLAS

18B20

GND

2 3

SO (150 mils)

(DS18B20Z)

N.C.

GND

DALLAS

18B20

N.C.

GND

N.C.

18B20

μSOP

(DS18B20U)

DS18B20

2 of 22

ORDERING INFORMATION

PART TEMP RANGE PIN-PACKAGE TOP MARK

DS18B20

-55°C to +125°C

3 TO-92

18B20

DS18B20+

-55°C to +125°C

3 TO-92

18B20

DS18B20/T&R

-55°C to +125°C

3 TO-92 (2000 Piece)

18B20

DS18B20+T&R

-55°C to +125°C

3 TO-92 (2000 Piece)

18B20

DS18B20-SL/T&R

-55°C to +125°C

3 TO-92 (2000 Piece)*

18B20

DS18B20-SL+T&R

-55°C to +125°C

3 TO-92 (2000 Piece)*

18B20

DS18B20U

-55°C to +125°C 8 μSOP

18B20

DS18B20U+

-55°C to +125°C 8 μSOP

18B20

DS18B20U/T&R

-55°C to +125°C 8 μSOP (3000 Piece)

18B20

DS18B20U+T&R

-55°C to +125°C 8 μSOP (3000 Piece)

18B20

DS18B20Z

-55°C to +125°C

8 SO

DS18B20

DS18B20Z+

-55°C to +125°C

8 SO

DS18B20

DS18B20Z/T&R

-55°C to +125°C

8 SO (2500 Piece)

DS18B20

DS18B20Z+T&R

-55°C to +125°C

8 SO (2500 Piece)

DS18B20

+Denotes a lead-free package. A “+” will appear on the top mark of lead-free packages.

T&R = Tape and reel.

*TO-92 packages in tape and reel can be ordered with straight or formed leads. Choose “SL” for straight leads. Bulk TO-92 orders are straight

leads only.

PIN DESCRIPTION

μSOP

TO-92

NAME FUNCTION

1, 2, 6,

7, 8

2, 3, 5,

6, 7

— N.C. No Connection

3 8 3 V

Optional V

. V

must be grounded for operation in

parasite power mode.

4 1 2 DQ

Data Input/Output. Open-drain 1-Wire interface pin. Also

provides power to the device when used in parasite power

mode (see the Powering the DS18B20 section.)

5 4 1 GND Ground

OVERVIEW

Figure 1 shows a block diagram of the DS18B20, and pin descriptions are given in the Pin Description

table. The 64-bit ROM stores the device’s unique serial code. The scratchpad memory contains the 2-byte

temperature register that stores the digital output from the temperature sensor. In addition, the scratchpad

provides access to the 1-byte upper and lower alarm trigger registers (T

and T

) and the 1-byte

configuration register. The configuration register allows the user to set the resolution of the temperature-

to-digital conversion to 9, 10, 11, or 12 bits. The T

, T

, and configuration

registers are nonvolatile

(EEPROM), so they will retain data when the device is powered down.

The DS18B20 uses Maxim’s exclusive 1-Wire bus protocol that implements bus communication using

one control signal. The control line requires a weak pullup resistor since all devices are linked to the bus

via a 3-state or open-drain port (the DQ pin in the case of the DS18B20). In this bus system, the

microprocessor (the master device) identifies and addresses devices on the bus using each device’s unique

64-bit code. Because each device has a unique code, the number of devices that can be addressed on one

DS18B20

3 of 22

bus is virtually unlimited. The 1-Wire bus protocol, including detailed explanations of the commands and

“time slots,” is covered in the 1-Wire Bus System section.

Another feature of the DS18B20 is the ability to operate without an external power supply. Power is

instead supplied through the 1-Wire pullup resistor via the DQ pin when the bus is high. The high bus

signal also charges an internal capacitor (C

), which then supplies power to the device when the bus is

low. This method of deriving power from the 1-Wire bus is referred to as “parasite power.” As an

alternative, the DS18B20 may also be powered by an external supply on V

Figure 1. DS18B20 Block Diagram

OPERATION—MEASURING TEMPERATURE

The core functionality of the DS18B20 is its direct-to-digital temperature sensor. The resolution of the

temperature sensor is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0.5°C,

0.25°C, 0.125°C, and 0.0625°C, respectively. The default resolution at power-up is 12-bit. The DS18B20

powers up in a low-power idle state. To initiate a temperature measurement and A-to-D conversion, the

master must issue a Convert T [44h] command. Following the conversion, the resulting thermal data is

stored in the 2-byte temperature register in the scratchpad memory and the DS18B20 returns to its idle

state. If the DS18B20 is powered by an external supply, the master can issue “read time slots” (see the

1-Wire Bus System section) after the Convert T command and the DS18B20 will respond by transmitting

0 while the temperature conversion is in progress and 1 when the conversion is done. If the DS18B20 is

powered with parasite power, this notification technique cannot be used since the bus must be pulled high

by a strong pullup during the entire temperature conversion. The bus requirements for parasite power are

explained in detail in the Powering the DS18B20 section.

The DS18B20 output temperature data is calibrated in degrees Celsius; for Fahrenheit applications, a

lookup table or conversion routine must be used. The temperature data is stored as a 16-bit sign-extended

two’s complement number in the temperature register (see Figure 2). The sign bits (S) indicate if the

temperature is positive or negative: for positive numbers S = 0 and for negative numbers S = 1. If the

DS18B20 is configured for 12-bit resolution, all bits in the temperature register will contain valid data.

For 11-bit resolution, bit 0 is undefined. For 10-bit resolution, bits 1 and 0 are undefined, and for 9-bit

resolution bits 2, 1, and 0 are undefined. Table 1 gives examples of digital output data and the

corresponding temperature reading for 12-bit resolution conversions.

4.7k

POWER-

SUPPLY

SENSE

64-BIT ROM

AND

1-Wire PORT

INTERNAL V

PARASITE POWER

CIRCUIT

MEMORY CONTROL

LOGIC

SCRATCHPAD

8-BIT CRC GENERATOR

TEMPERATURE SENSOR

ALARM HIGH TRIGGER (T

)

ALARM LOW TRIGGER (T

)

CONFIGURATION REGISTER

(EEPROM)

GND

DS18B20

5 of 22

The master device can check the alarm flag status of all DS18B20s on the bus by issuing an Alarm Search

[ECh] command. Any DS18B20s with a set alarm flag will respond to the command, so the master can

determine exactly which DS18B20s have experienced an alarm condition. If an alarm condition exists

and the T

or T

settings have changed, another temperature conversion should be done to validate the

alarm condition.

POWERING THE DS18B20

The DS18B20 can be powered by an external supply on the V

pin, or it can operate in “parasite power”

mode, which allows the DS18B20 to function without a local external supply. Parasite power is very

useful for applications that require remote temperature sensing or that are very space constrained.

Figure 1 shows the DS18B20’s parasite-power control circuitry, which “steals” power from the 1-Wire

bus via the DQ pin when the bus is high. The stolen charge powers the DS18B20 while the bus is high,

and some of the charge is stored on the parasite power capacitor (C

) to provide power when the bus is

low. When the DS18B20 is used in parasite power mode, the V

pin must be connected to ground.

In parasite power mode, the 1-Wire bus and C

can provide sufficient current to the DS18B20 for most

operations as long as the specified timing and voltage requirements are met (see the DC Electrical

Characteristics and AC Electrical Characteristics). However, when the DS18B20 is performing

temperature conversions or copying data from the scratchpad memory to EEPROM, the operating current

can be as high as 1.5mA. This current can cause an unacceptable voltage drop across the weak 1-Wire

pullup resistor and is more current than can be supplied by C

. To assure that the DS18B20 has sufficient

supply current, it is necessary to provide a strong pullup on the 1-Wire bus whenever temperature

conversions are taking place or data is being copied from the scratchpad to EEPROM. This can be

accomplished by using a MOSFET to pull the bus directly to the rail as shown in Figure 4. The 1-Wire

bus must be switched to the strong pullup within 10μs (max) after a Convert T [44h] or Copy Scratchpad

[48h] command is issued, and the bus must be held high by the pullup for the duration of the conversion

CONV

) or data transfer (t

= 10ms). No other activity can take place on the 1-Wire bus while the pullup

is enabled.

The DS18B20 can also be powered by the conventional method of connecting an external power supply

to the V

pin, as shown in Figure 5. The advantage of this method is that the MOSFET pullup is not

required, and the 1-Wire bus is free to carry other traffic during the temperature conversion time.

The use of parasite power is not recommended for temperatures above +100°C since the DS18B20 may

not be able to sustain communications due to the higher leakage currents that can exist at these

temperatures. For applications in which such temperatures are likely, it is strongly recommended that the

DS18B20 be powered by an external power supply.

In some situations the bus master may not know whether the DS18B20s on the bus are parasite powered

or powered by external supplies. The master needs this information to determine if the strong bus pullup

should be used during temperature conversions. To get this information, the master can issue a Skip ROM

[CCh] command followed by a Read Power Supply [B4h] command followed by a “read time slot”.

During the read time slot, parasite powered DS18B20s will pull the bus low, and externally powered

DS18B20s will let the bus remain high. If the bus is pulled low, the master knows that it must supply the

strong pullup on the 1-Wire bus during temperature conversions.

剩余21页未读，继续阅读

评论收藏

内容反馈

wangcheng813

粉丝: 0
资源: 9

温度芯片DS18B20+

评论0

最新资源

温度芯片DS18B20+

评论0

TM4C系列ds18b20温度传感器例程

ds18b20测温例程（tm4c123x）

TM4C123GH6PZ读取DS18B20数据

STC15W4K56+DS18B20+DHT11+电机控制温度传感器温湿度监控系统软件源码+说明文档.zip

DS18B20英文手册

温度芯片DS18B20+lcd显示

通过VHDL编程实现FPGA芯片与DS18B20温度传感器的数据传输

STM32之用FreeRTOS实现DS18B20、3.5寸显示屏、ADC测芯片温度(HAL库)

STM32温度传感器DS18B20加串口通信

DS18B20+DS1302+LCD1602

基于DS18B20的温度控制系统设计

ds18b20温度采集仿真

单片机课设资料-基于51单片机+DS1302+ds18b20+LCD1602B液晶模块的多功能数字时钟温度计设计.rar

使用STM32F103为主控制芯片 DS18B20数字温度传感器驱动程序.zip

1602液晶+DS1302时钟芯片+DS18B20温度传感器源程序

51+DS1302+DS18B20+LCD1602,显示时间,温度,可调时

温度芯片DS18B20%2B液晶1602经典仿真例子_有protues文件

STM32F103读取DS18B20温度数据.zip

1602+18B20+DS1302电子时钟源程序.zip_18b20_DS1302+AT89C52+1602_源程序_电子时钟

DS18B20_基于VHDL的温度传感器读写程序_

ARM芯片LPC2148驱动温度传感器DS18B20

c51 ds18b20 lm06l单片机C语言程序

verilog-format的配置文件

完整版 ISO 26262 最新版（2018）1-12部分.rar

中航光电_连接器手册（全）.pdf

STM32通过298N控制电机.zip

英飞凌AURIX TC27x D-Step芯片用户手册(Infineon-TC27x_D-step-UM-v02_02-EN.pdf)

【源码】基于贝叶斯优化的LSTM时间序列预测

全国大学生电子设计竞赛设计报告模板(最新).doc

最新资源