I got fed up with low quality modules from China, so started selling my own on Ebay.
These are my first two products:
TS001UH - Ultra High Accuracy & Precision Temperature Sensor using NXP SE95
TS001H - High Accuracy & Precision Temperature Sensor using NXP LM75b.
They share this same datasheet.
Where do I start...
ACCURACY, PRECISION, and CALIBRATION
TS001UH has worst-case ±1ºC from -25~100ºC at 0.03125ºC resolution.
TS001H has worst-case ±2ºC from -25~100ºC 0.125ºC resolution.
The accuracy above is the absolute worst-case according to NXP's SE95 datasheet and LM75B datasheet - much better than knowing what the typical accuracy is in my opinion.
I decided to go with these because they are already calibrated by NXP!
So... NO CALIBRATION IS NEEDED!!
I hate using thermistor and other cheaper temperature sensors that require calibration.
Honestly, how would a hobbyist or even for a small company to calibrate the resistors accurately.
One area lacked by other temperature sensor modules was the PCB design.
I had just one thing in my mind when designing mine - optimizing the thermal paths.
These temperature sensor chips have their sensing dies usually connected to the ground pins.
That's is why I flooded... literally flooded the entire board top and bottom with ground planes.
I was satisfied with the result. The temperature difference between the readings from the module, front, and back of the module was roughly the same. It did take some time (less than 1 min) however for the temperature to gradually transfer from the back to front of the board.
With my design, I could measure ambient and on another PCB by installing my module right on the board near the heatsource.
I don't want too many pins I have to connect.
That's why I installed onboard customizable address jumpers, and used 2-wire I2C bus interface.
You really just need 4 wires to communicate with the module!
There is one more pin however - it's an open-drain output from the chip that you can use to drive heater, alarm, and etc.
Also, four #4 installation holes are on the PCB if you want to use standoffs or screws.
There are so many cheap knockoffs on Ebay...
Chips with weird logos, part number, and etc.
They should not allowed to sell these honestly.
I am only using genuine parts from NXP, Panasonic, and Murata all purchased from Mouser.
Also I used oshpark for my PCB. Gold plated, and high quality. Made in US as well :]
Lastly, I don't understand why no modules in the market right now has absolutely no protections.
I know they are cheap, but I hated it when the main chip gets fried when I accidentally connected the power in reverse.
That's why I added over-current, voltage, and reverse polarity protections.
Basically I have a small 1Ohm resistor in series with my power pin that is acting like a fuse.
You could actually use this for debug the board as well - how much current is the module using.
Then I have a zener to clamp the voltage when over-voltage is applied.
Also the same zener shorts the power pins when reverse voltage is applied.
Cheap, but effective protections.
Pictures of my product:
All modules will be shipped in anti-static bags and bubble wrap envelops using air shipping from here in Vancouver BC.
Sample Arduino Code HERE
They are fully made in Canada.
Click HERE to buy these :]