ALLPCB
Thermometer Gun Usage and Battery Types
Ensuring an adequate supply of prevention equipment is necessary, and handheld infrared thermometers have become common in many offices. The following provides an analysis of typical handheld thermometer power solutions and related IC options.
Common battery configurations for portable thermometers include:
- One or two alkaline dry cells in series, providing 1.5V or 3.0V system power.
- Dedicated 9V battery power.
- Rechargeable lithium battery power.
Recommended IC Solutions
Single/Double Dry Cell Application
DIO6099 is an ultra-low-power, ultra-low-start-voltage synchronous-rectification boost converter. The operating input range supports 0.7V to 5.5V, and the output voltage is adjustable, supporting 1.5V to 5.0V settings. It has a standby current as low as 1uA, supports 300mA load startup, and is available in CSP-6, DFN2x2-6, and SOT23-6 packages. It is suitable for products requiring long battery life and operation at very low input voltages.
9V Battery Application
DIO7708 is a wide-input-voltage, low-noise, low-power, high-precision linear regulator. The operating input range supports 2.5V to 30V. Output options include adjustable and fixed voltages; fixed outputs are available in 1.2V, 1.5V, 1.8V, 2.5V, 3.0V, and 3.3V. Quiescent current can be as low as 4uA (lower-power variants are available). It delivers 60dB PSRR at 1kHz, supports 300mA output current, and typical output accuracy is within 2% (higher-accuracy variants are available). Packaging options include DFN2x2-6, SOT23-6, and TSOT23-6. This type of regulator is commonly used in high-voltage, long-life portable products.
Single-Cell Lithium Battery Application
DIO58056 is a high-voltage-tolerant linear charging management IC with maximum input tolerance up to 36V. It provides protection against input surges and high-voltage direct input conditions. Charge current supports up to 1A, adjustable between 50mA and 1A. The charge termination current is configurable. The IC supports AC-OK detection, full-charge indicator control, charge enable control, and other functions. It supports lithium battery charge voltages of 4.2V and 4.35V in different versions and is available in DFN2x2-8 and ESOP-8 packages. For general lithium battery chargers facing high-voltage or surge input conditions, the device's high-voltage tolerance is notable.
Precision Amplifier for Temperature Sensing
DIO2352 is a high-precision, very low-drift, low-noise, rail-to-rail operational amplifier. The operating supply supports 2.5V to 5.5V. Offset precision is specified at 0.012mV, noise is 40 nV/√Hz, and low drift is 0.01 μV/°C over the full temperature range. Bandwidth is 1.2MHz. Options include single, dual, and quad channels (dual-channel devices are commonly used for temperature sensing). Packaging options include SO-8, MSOP-8, and TSSOP-8. DIO Micro is one of the domestic suppliers in the Chinese market for high-performance operational amplifiers.
System-Level Considerations
Temperature measurement products are subdivided into ear thermometers, forehead thermometers, and clinical thermometers, and their system architectures differ slightly. Overall solutions may also include analog switches, LED display drivers, boost buzzer drivers, Wi-Fi/Bluetooth modules, voltage regulators, and other high-performance op amps.
