Overview of Thermistor Interface Chip Technology: Introduce the basic principles and technical types of thermistor interface chips, including traditional NTC solutions and new integrated solutions.
Recommended by application scenario classification: Specific chip solutions are recommended for three scenarios: consumer electronics and the Internet of Things, automotive electronics and industrial control, and medical and high-precision measurement, using chip models as subheadings.
Comprehensive selection guide: Summarize key parameter comparison tables and technical trends, and provide a selection decision-making framework.
Design considerations: Provide practical design suggestions from three aspects: signal conditioning, thermal management, and interface selection.
Next, I will begin writing the main text of the recommended solution for thermal interface chips.
Comprehensive selection guide for thermal interface chips: recommend the optimal solution according to application scenarios
Overview of Thermal Interface Chip Technology
As the core component of temperature sensing systems, thermal interface chips are mainly responsible for converting physical temperature changes into processable electrical signals. Their performance directly affects the accuracy, response speed, and reliability of the entire temperature measurement system. The current technical solutions are mainly divided into two directions:
Traditional NTC thermistor matching solution: an analog solution based on negative temperature coefficient (NTC) thermistor, which needs to be used in conjunction with signal conditioning circuit and ADC converter. This type of solution has lower costs, but it has inherent drawbacks such as nonlinear characteristics (resistance temperature relationship follows an exponential curve), poor consistency (requiring manual calibration), and insufficient long-term stability (increasing drift over time). Typical representatives include DT series gold electrode NTC chips and Vishay NTCSC series surface mount thermistors.
New integrated digital solution: using CMOS technology to integrate temperature sensors with signal conditioning, ADC conversion, and digital interfaces on a single chip, directly outputting linearized digital temperature values. This type of solution overcomes the shortcomings of traditional NTC and has excellent linearity, factory calibration accuracy, and interface standardization advantages, but the cost is relatively high. Typical representatives include the nano core micro NST series and the sensitive source M117A.
In terms of interface technology, modern thermal interface chips have covered all mainstream output methods:
Analog voltage output: Directly outputting voltage signals proportional to temperature, simplifying circuit design
Digital interfaces: including I ² C, SPI, single bus, etc., suitable for digital system integration
Specialized protocols such as SENT (Automotive Electronics) and Pulse Counting (Low Power Applications)
2. Recommended by application scenario classification
2.1 Consumer Electronics and IoT Applications
Such applications typically require small size, low power consumption, and cost-effectiveness, with relatively relaxed requirements for extreme temperature accuracy (around ± 1 ℃ is sufficient). Simultaneously, good production consistency and simplified interface design are required.
2.1.1 Vishay NTCSC0402 series
Core features: Adopting 0402 ultra micro package (0.4 × 0.2mm), 1% resistance accuracy is equivalent to ± 0.2 ℃ temperature measurement accuracy, providing multiple resistance options of 10K/47K/100K, and B value range of 3435K4050K
Design advantages: Fully automatic mounting compatibility, support reflow soldering process, comply with RoHS standards and have no exempt substances, especially suitable for skin contact temperature measurement of wearable devices and temperature monitoring of TWS earphones' charging compartment
Typical application circuit: When used with MCU built-in ADC, a simple voltage divider circuit and 0.1 μ F decoupling capacitor need to be configured, and attention should be paid to keeping the wiring away from the heat source
Cost positioning: Unit price of approximately $1.5 (purchased per thousand pieces), with significant cost advantages
2.1.2 Zhaoqing Aisheng DT series gold electrode NTC
Innovative design: adopting unique gold electrode processing technology and aluminum/silver wire bonding process, significantly improving electrode oxidation resistance and long-term stability
Size breakthrough: The minimum size reaches 0.3 × 0.3 × 0.2mm (DT104 □ 3964F), making it one of the smallest NTC chips in the industry, providing possibilities for ultra compact IoT modules
Accuracy selection: Provides multiple accuracy options of ± 0.3%, ± 1%, ± 3%, among which the ± 0.3% level (DT473 □ 4050A) is particularly suitable for medical grade wearable devices
Customization capability: Supports full parameter customization of resistance (1k1000k Ω), B-value (3200K4500K), and size (0.34.0mm)
2.1.3 Nanochip NST235 Analog Output Sensor
Revolutionary Replacement: Directly replacing traditional thermistor voltage divider circuits, outputting linear analog voltage (10mV/℃), eliminating NTC nonlinear errors
Performance advantages:
Full temperature range error<± 2.5 ℃ (40-125 ℃)
Ultra low working current 20 μ A/standby 0.1 μ A
Thermal response constant τ 63%=0.418 seconds
Compatible design: The pins are fully compatible with TMP235 and support SOT233/SC705 packaging
Scenario adaptation: Room temperature application scenarios such as smart home controllers, router temperature monitoring, etc
2.2 Automotive Electronics and Industrial Control Applications
>This type of scenario requires extreme temperature tolerance, anti-interference ability, and functional safety certification, especially for automotive electronics that comply with AECQ100 standards, while industrial environments emphasize wide temperature range accuracy stability.
2.2.1 Melexis MLX90342 Four Channel Thermocouple Interface
Innovative architecture: Integrated four-way independent thermocouple front-end, supporting K/J/N/T/E type thermocouples, built-in cold junction compensation algorithm (CJC) and adaptive linearization
Excellent parameters:
Measurement range: 40 ℃ to 1300 ℃ (exhaust gas temperature measurement)
Accuracy ± 2.5 ℃ at high temperature of 1100 ℃
Refresh rate of 100Hz (meets dynamic monitoring of turbocharging)
SENT protocol output (compliant with SAE J2716 standard)
Safety features: Provides rich diagnostic functions such as open/short circuit diagnosis, ADC self-test, data CRC verification, etc
Application positioning: Gasoline/diesel engine exhaust system (DOC/SCR/DPF), turbocharger temperature management, EGR valve control
2.2.2 Taijing Technology 38.4MHz Thermistor Crystal
Technological innovation: Integrating thermal compensation network with quartz crystal to offset frequency temperature drift
Vehicle specification certification: Passed Qualcomm SA515 platform certification and AECQ200 standard, supports working temperature of 40-125 ℃
Application value: Providing core time base components for automotive grade 5G modules (CV2X) and high-precision ECU clocks
Domestic breakthrough: the first crystal supplier in China to be certified by Qualcomm in car platform
2.2.3 Shanghai Hangxin ACM32F403 Multi Interface Controller
Integration solution: As a thermal print head control MCU, integrate key functions:
12 bit 2Msps ADC (real-time monitoring of print head temperature)
Advanced timer (precise control of heating time)
Multi channel PWM (stepper motor cooperative control)
Temperature Management Algorithm: Implementing Dynamic Temperature Compensation to Prevent Thermal Print Head from Overheating and Damage
Industrial expansion: also applicable to systems that require precise temperature control, such as industrial printing equipment and medical detectors
2.3 Medical and high-precision measurement applications
The core requirements for such applications are ultra-high precision (≤± 0.5 ℃), low-power operation, and long-term stability, while also having strict requirements for noise suppression and anti-interference.
2.3.1 Sensitive Source Sensing M117B Digital Temperature Chip
Precision breakthrough:
Accuracy within the range of 0 ℃~50 ℃ ± 0.5 ℃
Full range (70~150 ℃) accuracy ± 2 ℃
16 bit ADC provides 0.004 ℃ resolution
Power consumption optimization:
Standby current 0.1 μ A
Single measurement average current 5.2 μ A (once per second)
Intelligent configuration:
Adjustable conversion time (4ms/5.5ms/10.5ms)
32-bit user EEPROM stores calibration data
ALERT pin supports temperature threshold interrupt
Typical applications: Medical electronic thermometers, vaccine cold chain monitoring, high-precision environmental recorders
2.3.2 Nanochip NST86 I ² C Digital Sensor
System integration advantage: I ² C interface directly interfaces with MCU, simplifying PCB layout
Performance Highlights:
Full temperature range error ± 1.5 ℃ (55~125 ℃)
500 μ A driving capability (supporting long cable applications)
Package selection: SOT233/SC705 package available, compatible with TI LMT86 pin
Application direction: Temperature monitoring of medical monitoring equipment motherboards, constant temperature control of laboratory instruments
3 Comprehensive Selection Guide
To facilitate quick decision-making, the following key parameters are compared:
|Chip model | Temperature measurement accuracy (℃) | Interface type | Power consumption characteristics | Operating range (℃) | Best application scenario|
| Vishay NTCSC0402 | ± 0.2@25 ℃ | Analog resistance | Passive devices with no power consumption | 40~125 | Wearable devices/consumer electronics|
|Zhaoqing Aisheng DT473 | ± 0.3% | Analog resistor | Passive device with no power consumption | 50~150 | Miniature IoT module|
|Nanochip NST235 | ± 2.5 (max) | Analog voltage | 20 μ A operation/0.1 μ A sleep | 40~125 | Smart home/network devices|
| Melexis MLX90342 | ± 2.5@1100 ℃ | SENT | 8mA (active) | 40~155 | Automotive exhaust system|
|Sensitive Source M117A | ± 0.5 (0~50 ℃) | I ² C | 5.2 μ A (average) | 70~150 | Medical Instruments/Cold Chain Monitoring|
|Hangxin ACM32F403 | ADC dependent design | Multi interface | Low power mode<10 μ A | 40~105 | Thermal printing/industrial control system|
Table: Comparison of Key Parameters of Mainstream Thermal Interface Chips
3.1 Technological Development Trends
Integration: Traditional discrete solutions (NTC+amplifier+ADC) are rapidly being replaced by single-chip solutions, such as NST235 directly replacing thermistor voltage divider circuits in printer head temperature control
Domestic substitution: Domestic manufacturers have made breakthroughs in the high-end field, such as Taijing Technology passing Qualcomm automotive certification and Naxin Micro achieving full coverage of interface protocols
Intelligent diagnosis: The new generation of chips integrates self diagnostic functions (such as open circuit detection of MLX90342) to enhance system reliability
Ultra low power consumption: adopting intermittent working mode, such as M117A automatically sleeping after a single measurement, significantly extending battery life
4 Design considerations
In practical engineering design, the following key factors need to be comprehensively considered to avoid common problems:
Signal conditioning optimization:
When using NTC, SteinhartHart formula calibration must be implemented in the software: ` 1/T=A+B · ln (R)+C · [ln (R)] ³ `, where A/B/C are device specific parameters
For long-term transmission, priority should be given to current type outputs or digital interfaces (such as the I ² C of M117A) to avoid attenuation of analog voltage signals
Thermal management design:
Ensure a low thermal resistance path between the sensor and the object being measured: fill the air gap with thermal conductive silicone grease, and use a thermal through-hole array in PCB design
To avoid self heating errors: Apply power<1mW to NTC (recommended<60mW for DT series), and check the self heating effect of active devices (such as M117B peak current 0.45mA)
Interface selection strategy:
SENT protocol (such as MLX90342) is the preferred choice for automotive electronics, with strong anti-interference and diagnostic capabilities
The I ² C interface (such as M117A) is suitable for board level short distance transmission, and attention should be paid to the bus capacitance limit (<400pF)
The single bus scheme is suitable for node distributed systems, but it requires sacrificing transmission speed
Certification compliance:
Automotive electronics must choose AECQ100 certified components (such as MLX90342)
Medical devices should prioritize the use of chips produced through the ISO 13485 system (such as the medical grade version of M117A)
Industrial environment considers IEC 610004 electromagnetic compatibility standard
Through scientific selection and rational design, modern thermal interface chips can meet the temperature detection needs of all fields from consumer electronics to automotive electronics, while promoting the continuous evolution of temperature measurement technology towards higher accuracy, lower power consumption, and stronger intelligence.