This is an overview of the LM45 series(LM45B, LM45C ) and the OSS-ECAL offering for the LM45 series. The LM45 series is a temperatures sensor IC (–20 °C to +100 °C) manufactured by Texas Instruments.
MCU interface : ADC
CAUTION:Please be sure to refer to the latest version of the Datasheet prior to actual design.
LM45 series(LM45B, LM45C)
General description
The LM45 series( LM45B, LM45C ) are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM45 does not require any external calibration or trimming to provide accuracies of ±2°C at room temperature and ±3°C over a full −20 to +100°C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM45’s low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with a single power supply, or with plus and minus supplies. As it draws only 120 μA from its supply, it has very low self-heating, less than 0.2°C in still air. The LM45 is rated to operate over a −20° to +100°C temperature range.
Feature
- Calibrated Directly in ° Celsius (Centigrade)
- Linear + 10.0 mV/°C Scale Factor
- ±3°C Accuracy Guaranteed
- Rated for Full −20° to +100°C Range
- Suitable for Remote Applications
- Low Cost Due to Wafer-Llevel Trimming
- Operates from 4.0V to 10V
- Less than 120 μA Current Drain
- Low Self-Heating, 0.20°C in Still Air
- Nonlinearity Only ±0.8°C Max Over Temp
- Low Impedance Output, 20Ω for 1 mA Load
Application
- Battery Management
- FAX Machines
- Printers
- Portable Medical Instruments
- HVAC
- Power Supply Modules
- Disk Drives
- Computers
- Automotive
OSS-ECAL specification
API Function
etSTS oLM45B( etCMD cmd, float32* rlt )
The oLM45B function is an API function that executes LM45 series(LM45B, LM45C) processing according to the command in the argument.
| Return value | etSTS | OSS-ECAL status code | |
| eSTS_FIN | Completed successfully | ||
| eSTS_ERR_MIN | Minimum temperature error (rlt is minimum temperature) | ||
| eSTS_ERR_MAX | Maximum temperature error (rlt is maximum temperature) | ||
| eSTS_ERR_HAL_ADC | HAL ADC Error | ||
| eSTS_ERR_COMMAND_CODE | Command selection error | ||
| eSTS_ERR_OTHERS_RUN | Other components are executing the process | ||
| eSTS_ERR_HAL_OTHERS_RUN | Other application is running HAL | ||
| eSTS_ERR_ADC_OBJECT | AD conversion object selection error | ||
| Parameter IN | etCMD cmd | OSS-ECAL command code | |
| eCMD_START | Command to start AD conversion. | ||
| eCMD_READ | Command that reads the AD conversion value, converts the AD conversion value to a characteristic Temperature, and stores the Temperature in rlt. AD conversion value to temperature conversion equation Voltage value = (AD conversion value × VDD) / ( 2AD bit ) Temperature = ((voltage value – voltage offset value) / gain) + Temperature offset value (Min, Max Limit) | ||
| eCMD_START_READ | Command that starts AD conversion, waits for AD conversion to finish, reads out the AD conversion value, converts the AD conversion value to a characteristic Temperature, and stores the Temperature in rlt. AD conversion value to temperature conversion equation Voltage value = (AD conversion value × VDD) / ( 2AD bit ) Temperature = ((voltage value – voltage offset value) / gain) + Temperature offset value (Min, Max Limit) | ||
| Parameter OUT | float32* rlt | Temperature -20.0 to +100.0 [°C] |
Command Correspondence Table by HAL
| Arduino | eCMD_START_READ |
| ARM Mbed | eCMD_START_READ |
| Infineon ModusToolbox | eCMD_START_READ |
| NXP MCUXpresso iMXRT1051B_1052B | eCMD_START eCMD_READ eCMD_START_READ |
| Renesas SSP | eCMD_START eCMD_READ eCMD_START_READ |
| STM STM32Cube FW_F4 | eCMD_START eCMD_READ eCMD_START_READ |
etSTS oLM45B_START(void)
The oLM45B_START function is an API function to start AD conversion of the LM45 series(LM45B, LM45C).
| Return value | etSTS | OSS-ECAL status code | |
| eSTS_FIN | Completed successfully | ||
| eSTS_ERR_HAL_ADC | HAL ADC Error | ||
| eSTS_ERR_OTHERS_RUN | Other components are executing the process | ||
| eSTS_ERR_HAL_OTHERS_RUN | Other application is running HAL | ||
| eSTS_ERR_ADC_OBJECT | AD conversion object selection error |
Function Correspondence Table by HAL
| Arduino | – |
| ARM Mbed | – |
| Infineon ModusToolbox | – |
| NXP MCUXpresso iMXRT1051B_1052B | X |
| Renesas SSP | X |
| STM STM32Cube FW_F4 | X |
etSTS oLM45B_READ( float32* rlt )
The oLM45B_READ function is an API function that checks for the end of AD conversion of the LM45 series(LM45B, LM45C), reads the AD conversion value, converts the AD conversion value to a characteristic temperature, and stores the temperature in rlt.
AD conversion value to temperature conversion equation
Voltage value = (AD conversion value × VDD) / ( 2AD bit )
Temperature = ((voltage value – voltage offset value) / gain) + Temperature offset value (Min, Max Limit)
| Return value | etSTS | OSS-ECAL status code | |
| eSTS_FIN | Completed successfully | ||
| eSTS_ERR_MIN | Minimum temperature error (rlt is minimum temperature) | ||
| eSTS_ERR_MAX | Maximum temperature error (rlt is maximum temperature) | ||
| eSTS_ERR_HAL_ADC | HAL ADC Error | ||
| eSTS_ERR_TIMEOUT | ADC Timeout error (AUTOSAR only) | ||
| eSTS_ERR_OTHERS_RUN | Other components are executing the process | ||
| eSTS_ERR_ADC_OBJECT | AD conversion object selection error | ||
| Parameter OUT | float32* rlt | Temperature -20.0 to +100.0 [°C] |
Function Correspondence Table by HAL
| Arduino | – | |
| ARM Mbed | – | |
| Infineon ModusToolbox | – | |
| NXP MCUXpresso iMXRT1051B_1052B | X | |
| Renesas SSP | X | |
| STM STM32Cube FW_F4 | X | Time-out time HAL_MAX_DELAY |
etSTS oLM45B_START_READ( float32* rlt )
The oLM45B_START_READ function is an API function that starts an AD conversion of the LM45 series(LM45B, LM45C), waits for the AD conversion to finish, reads the AD conversion value, converts the AD conversion value to a temperature characteristic, and stores the temperature in rlt.
AD conversion value to temperature conversion equation
Voltage value = (AD conversion value × VDD) / ( 2AD bit )
Temperature = ((voltage value – voltage offset value) / gain) + Temperature offset value (Min, Max Limit)
| Return value | etSTS | OSS-ECAL status code | |
| eSTS_FIN | Completed successfully | ||
| eSTS_ERR_MIN | Minimum temperature error (rlt is minimum temperature) | ||
| eSTS_ERR_MAX | Maximum temperature error (rlt is maximum temperature) | ||
| eSTS_ERR_HAL_ADC | HAL ADC Error | ||
| eSTS_ERR_OTHERS_RUN | Other components are executing the process | ||
| eSTS_ERR_HAL_OTHERS_RUN | Other application is running HAL | ||
| eSTS_ERR_ADC_OBJECT | AD conversion object selection error | ||
| Parameter OUT | float32* rlt | Temperature -20.0 to +100.0 [°C] |
Function Correspondence Table by HAL
| Arduino | X | |
| ARM Mbed | X | |
| Infineon ModusToolbox | X | |
| NXP MCUXpresso iMXRT1051B_1052B | X | |
| Renesas SSP | X | |
| STM STM32Cube FW_F4 | X | Time-out time HAL_MAX_DELAY |
HAL Support List
OSS-ECAL’s HAL support is as follows. (The list is being expanded sequentially.) Please note that even if the same HAL is used, different versions, MCUs, and development environments may not work together.
| Manufacturer | SDK/IDE Tool | HAL Name | Ver | HALNAME | Support |
|---|---|---|---|---|---|
| Arduino | Arduino IDE | Arduino | 1.8.6 | ARDUINO | X |
| Arm | Keil MDK v6 | Mbed OS | 6.17.0 | MBED | X |
| Debian | – | GNU/Linux | 10.3 | Linux | – |
| Infineon | ModusToolbox | mtb-hal-cat1 | 2.4.3 | ModusToolbox | X |
| NXP | MCUXpresso SDK | SDK_2.x_EVKB-IMXRT1050 | 2.16 | iMXRT1051B1052B | X |
| NXP | PlatformSDK_S32K1_2022_02 | AUTOSAR MCAL | 4.4 | MCAL | – |
| Renesas | Synergy Software Package | HAL | 2.6.0 | SSP | X |
| STMicroelectronics | STM32Cube | STM32CubeF4 | V1.28.1 | STM32F4 | X |
Development environment
The MCU and development environment during OSS-ECAL development are as follows.
| HALNAME | Manufacturer | Board | MCU | IDE |
|---|---|---|---|---|
| ARDUINO | Arduino | 1.Mega 2560 Rev3 2.Arduino Pro Mini 3.3V | ATmega2560 ATmega328P | Arduino IDE 2.3.3 |
| MBED | STMicroelectronics | STM32 Nucleo-64 boards | STM32F401RETx | Arm Keil Studio Cloud |
| Linux | BeagleBoard | BeagleBone Black | TI AM335x | – |
| ModusToolbox | Infineon | CY8CPROTO-063-BLE PSoC 6 BLE Prototyping Kit | CYBLE-416045-02 | ModusToolbox |
| iMXRT1051B1052B | NXP | IMXRT1050-EVKB | i.MX RT1050 | MCUXpresso IDE |
| MCAL | STMicroelectronics | S32K144EVB-Q100 | S32K144 | S32 Design Studio for S32 Platform |
| SSP | Renesas | S7G2 SK | R7FS7G27H3A01CFC | e² studio for Renesas Synergy |
| STM32F4 | STMicroelectronics | STM32 Nucleo-64 boards | STM32F401RETx | STM32CubeIDE |
File Structure
| Folder* | File | Summary |
|---|---|---|
| LM45B_HALNAME_VERSION/sample | sample.c (.cpp) | Sample Application Program |
| sample.h | Sample Application Header | |
| LM45B_HALNAME_VERSION | oLM45B.c (.cpp) | OSS-ECAL Program for LM45 series(LM45B, LM45C) |
| oLM45B.h | OSS-ECAL Header for LM45 series(LM45B, LM45C) | |
| LM45B_ARDUINO.ino | Sample application programs for Arduino | |
| oss_ecal.h | OSS-ECAL Common Header (Ver 01.00.00 or later) | |
| user_setting.c (.cpp) | Const and Table of User setting | |
| user_setting.h | Header of User setting | |
| readme.md | Readme | |
| OSS-ECAL Terms of Use.txt | OSS-ECAL Terms of Use |
* For HALNAME, please refer to HAL Support.
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Built-in How to
How to incorporate OSS-ECAL into user programs
How to incorporate multiple OSS-ECALs in a user program (same MCU function)
How to incorporate multiple OSS-ECALs in a user program (different MCU function)
How to incorporate multiple identical electronic components into a user program
How to reduce the impact on user programs by replacing electronic components
CAUTION
The sample version of OSS-ECAL is not intended to be used with Threads (Tasks) or interrupts of different priority. Please do not use it as in the example below.
Example: If each sensor is assigned to the same ADC group and the OSS-ECAL API is executed in processes with different priorities, correct values may not be obtained.
ADC Gr0 Ch0 Temperature sensor AD22100A 100ms cycle Thread (low priority) to take in temperature
ADC Gr0 Ch1 Pressure sensor MPX5999D Event interrupts (high priority) to take pressure