LMT84LPM - 1.5V Analog Temperature Sensor TO-92 | TI
MPN： LMT84LPM ✓ 啟用中LMT84LPM 概覽
An analog output temperature sensor is a type of temperature sensor IC (part of the broader sensor and semiconductor hierarchy) that converts measured die temperature directly into a proportional voltage, which a microcontroller ADC can read without digital bus configuration. Unlike thermistors, analog sensors provide a linear, calibrated transfer function; unlike digital sensors such as the TMP117, they require no I2C/SMBus protocol stack.
Key features include 1.5V-capable single-supply operation, 10 uA-class current consumption for effective power-cycling in battery-powered designs, a Class-AB push-pull output capable of sourcing and sinking heavy loads, 0.7 ms power-on time, and typical accuracy of plus or minus 0.4C (plus or minus 2.7C maximum) per the TI LMT84 datasheet.
Architecturally, the LMT84 uses a CMOS bandgap-derived temperature-dependent voltage with an output stage that maintains linearity across the full -50C to +150C range while drawing micropower supply current, enabling years of operation from a small lithium cell.
Typical applications include battery-powered environmental monitoring, HVAC thermal sensing, portable medical devices, automotive sub-systems (via the AEC-Q100 qualified LMT84-Q1 variant), and appliance over-temperature detection.
Design tip: because output gain is negative (-5.5 mV/C), invert the transfer function in firmware; add a 0.1 uF bypass capacitor close to the supply pin for stable ADC readings.
直接替換替代品，適用於 LMT84LPM — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
LMT84-Q1
✅ 直接替換📋 參考替代品（不在目錄中）
LMT85
✅ 直接替換📋 參考替代品（不在目錄中）
LM94022
✅ 直接替換📋 參考替代品（不在目錄中）
TMP235
✅ 直接替換📋 參考替代品（不在目錄中）
TMP36
⚡ 相同封裝 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
LMT84LPM 最大額定值與電氣特性
| 感測器類型 | Analog output local temperature sensor |
| 輸出類型 | Analog voltage (Class-AB push-pull) |
| Temperature Sensitivity | -5.5 mV/C |
| Measuring Range | -50C to +150C |
| Accuracy (typical) | +/-0.4C |
| Accuracy (maximum) | +/-2.7C |
| Supply Voltage (min) | 1.5 V |
| 靜態電流 | 5.4 uA |
| Power-On Time | 0.7 ms |
| 封裝 | TO-92-3 (LPM) |
| 安裝類型 | Through Hole |
| 工作溫度 | -50C to +150C |
| Output Structure | Push-pull (strong source and sink capability) |
| RoHS 狀態 | Compliant |
| Automotive Variant | LMT84-Q1 (AEC-Q100 Grade 0) |
LMT84LPM 腳位配置
| 腳位 1 | GND — Ground reference |
| 腳位 2 | VTEMP — Analog temperature output (-5.5 mV/C) |
| 腳位 3 | VDD — Supply input (1.5V min) |
典型應用
LMT84LPM 適用於 6 應用s: Battery-Powered Environmental Monitoring, HVAC and Thermostat Sensing, Automotive Thermal Monitoring, Portable Medical Devices, Appliance Over-Temperature Protection, IoT Sensor Nodes and Smart Home.
Battery-Powered Environmental Monitoring
The LMT84 fits battery-powered sensors because its 1.5V minimum supply and 5.4 uA quiescent current allow direct connection to a lithium coin cell without a boost converter. With 0.7 ms power-on time, designers can duty-cycle the sensor, sampling temperature in sub-millisecond windows and shutting down between readings, reducing average consumption far below 1 uA. The Class-AB output drives a microcontroller ADC input directly. This combination supports multi-year battery life in wireless environmental loggers.
推薦
HVAC and Thermostat Sensing
In HVAC systems, room and duct temperatures from -20C to +60C sit well inside the LMT84's -50C to +150C range. The linear -5.5 mV/C transfer function gives roughly 30 mV per 5C change, adequate resolution for a 10-bit ADC, while +/-0.4C typical accuracy is comparable to NTC thermistor solutions without divider resistors or lookup tables. Because it replaces thermistor divider networks, the LMT84 simplifies BOM and calibration while the push-pull output tolerates long wiring runs to the controller board.
推薦
Automotive Thermal Monitoring
For automotive programs, the LMT84-Q1 variant is AEC-Q100 Grade 0 qualified on an automotive grade flow, covering -40C to +150C ambient conditions found in cabin, body, and under-hood-adjacent modules. Its 1.5V-capable micropower operation suits always-on body electronics monitored from low-voltage rails, and the analog output can feed either an MCU ADC or a window comparator for fault detection. Using the Q1 part removes qualification risk in ISO 26262-relevant monitoring paths.
推薦
Portable Medical Devices
Portable medical devices such as thermometers and wearable monitors benefit from the LMT84's low-voltage, low-current operation: 5.4 uA quiescent draw and 1.5V supply operation preserve coin-cell life in body-temperature probes. The +/-0.4C typical accuracy is sufficient for consumer health monitoring, and 0.7 ms power-on time enables instant-on readings for patient-facing devices. The analog output simplifies firmware compared to I2C digital sensors, shortening development cycles for cost-sensitive medical consumables.
推薦
Appliance Over-Temperature Protection
White goods and appliances require robust over-temperature supervision near motors, heaters, and power supplies. The LMT84's +150C upper range covers most appliance hot spots, and its push-pull output can directly drive a comparator for a hard trip signal without firmware dependence. Because the output is linear and monotonic, a simple resistor divider can set a warning threshold while the MCU reads graded temperature for derating logic. The 5.4 uA consumption keeps protection circuits negligible on standby power budgets.
推薦
IoT Sensor Nodes and Smart Home
Smart-home IoT endpoints (door sensors, climate pucks, leak detectors) rely on the LMT84 for ambient temperature with minimal energy cost. Its analog interface eliminates I2C address conflicts in multi-sensor nodes, and the micropower supply current plus 0.7 ms wake time pairs naturally with duty-cycled wireless MCUs. With a -5.5 mV/C gain, a 10-bit ADC referenced at 1.8V resolves about 0.6C steps, adequate for comfort-level reporting, while costing a fraction of digital sensor alternatives.
推薦
推薦產品摘要
工程參考資料，適用於 LMT84LPM — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | LMT84-Q1 | LMT85 | LM94022 | TMP235 |
|---|---|---|---|---|---|
| Package | TO-92-3 (LPM) | TO-92-3 / SC70-5 - same pinout | TO-92 / SC70 - similar pinout | similar pinout per TI compare tool | similar pinout per TI compare tool |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Gain | -5.5 mV/C fixed | -5.5 mV/C fixed | selectable -13.6/-10.9/-8.2/-5.5 mV/C | pin-selectable gain | different average sensor gain |
| Typical Accuracy | +/-0.4C | +/-0.4C | comparable accuracy | comparable accuracy | comparable accuracy |
主要差異化特點
- Lowest-voltage operation in the LMT8x family (對比LMT85)
- Simplicity vs selectable-gain parts (對比LM94022)
- Micropower duty-cycling (對比TMP36)
設計說明
Place a 0.1 uF ceramic bypass capacitor directly across VDD and GND of the LMT84. For the TO-92 LPM package, keep lead lengths short so the die tracks the ambient/board temperature rather than self-heating. If sensing air temperature, orient the TO-92 body away from heat sources and allow airflow; thermal mass of the package adds response lag of several seconds.
Because quiescent current is only 5.4 uA and power-on time is 0.7 ms, duty-cycling the sensor supply (via a GPIO-driven load switch or MCU pin) yields dramatic energy savings in battery designs. After power-up, allow the output to settle per the datasheet power-on specification before sampling the ADC; sampling too early returns an invalid voltage.
The LMT84 gain is negative (-5.5 mV/C): voltage decreases as temperature rises, which trips up firmware ported from TMP36-style positive-gain sensors. Use the datasheet transfer function/lookup table rather than a single-point calibration. Also ensure the ADC input impedance or sampling capacitor does not load the push-pull output beyond its rated drive, and never exceed the datasheet maximum supply voltage.
合規資訊
RoHS compliance per TI product page. Automotive qualification applies to the LMT84-Q1 variant only (AEC-Q100 Grade 0, automotive grade flow).
